WE sometimes speak of knowledge as if it were a body of truths existing independently of any human brain. Speaking in this way we say that mathematics is a part of knowledge, and that 2 + 2 = 4 is a proposition in mathematics. We speak of philosophy in the same way. It is a body of thought. It exists historically in various movements. It has developed. It takes this direction or that.

To speak in this way is very convenient. But it is, after all only a manner of speech. Knowledge actually exists only as a number of psychic events in the minds of knowers. Philosophy only exists in the philosophical thoughts of individual thinkers. Philosophy in general is an abstraction, like humanity. Humanity only exists as actual men, philosophy as actual processes of thought. There is your philosophy and my philosophy. There are also the philosophies of Smith, Jones, and Robinson. Philosophy in general is only the aggregate of all these, or else an abstraction from them.

My philosophy, then, must take its rise within my own mind, must begin, develop, and end there. I may of course, borrow it from others. It need not be original. Or it may consist of new thoughts which no one ever had before me. But in either case it is equally a process which begins and ends solely within my own mind.

Its starting-point must be within me. Now it will generally be admitted by all schools of thought that philosophy must in some sense take its rise from experience To which I pose at once the crucial question: whose experience? And there can only be one answer. Each individual thinker must necessarily base his own philosophy on, and understand the philosophies of others in terms of his own individual experience. I must begin philosophizing from my experience, you from yours.

Philosophers and men of science are apt to talk of experience as if it were impersonal, as if there were but one experience, and as if it were something which exists independently of experiencing minds. This, like ‘knowledge' and 'philosophy', is no doubt a quite legitimate abstraction which serves the purposes of thought. But an abstraction it is. Abstraction is the work of thought, how-ever. It is the end-result of a process, not the beginning. Hence an impersonal and independent experience is not the proper starting-point of philosophy. It is not a datum.

The concretes from which the abstraction of an impersonal experience is made can only be the individual experiences of each of us. It is here that we have to begin. And this reduces itself to the position that each of us must perforce take as the ultimate premiss of his philosophy nothing except his own individual experience. For each of us is, in some sense, shut up within his own mind. We can only interpret the experiences of others, when they are communicated to us, by translating them into terms of our own experiences. When you speak of 'red’, I can only understand this by interpreting it in terms of my own perceptions of red. I cannot directly see your red. I can only see my own and suppose that yours is like it. And this supposition is itself a result of thought, not a datum.

In general each mind is at first only aware of its own experience. And it never to the end has any direct awareness of the experiences of others. All such knowledge is indirect and derivative. It is the result of a process, and is not given.

I am aware, of course, that some philosophers assert that we know of the existence of other minds by a direct apprehension of them. We shall have to consider this assertion, and what it means, very carefully in the sequel. Whatever it may mean, however, I do not think it can be held to contradict the position here taken up. It will hardly be alleged that I can ever directly see your sensation of redness any more than I can feel the pain in your leg. Even telepathic communication proves nothing to the contrary. Suppose that X thinks of a number, and that this number is flashed telepathically into the mind of Y. It is still true that Y is aware of it only as a part of his own experience, not as a part of X's. Telepathy, if it is a reality, proves no more as regards our present point than does ordinary communication by speech. By speech, too an idea is transferred from one mind to another, but this means that a similar idea is generated in the second mind, not that numerically the same and identical idea exists in both minds. Each, after all, can only apprehend his own private experience, and is shut off from all others. And it is to be observed, finally, that even if we are aware of other minds by direct apprehension, that awareness is still to each of us a part of his own private experience. X's direct perception of Y's mind, if it exists, is just as much a part of X's individual experience as is his direct perception of red.

The necessity of philosophizing in terms of one's own experience may further be illustrated by inquiring how in fact we understand the philosophies of other thinkers. Kant asserted that geometrical axioms are necessarily true. We are not here concerned with whether this opinion is correct, but with the question how we understand it. And it is obvious that each of us can only understand it by testing it in his own private mental experience. He will ask himself the questions: 'Do i find the axioms self-evident? Do they appear necessary to me? Do they compel my mind?' And when philosophers speak of sensations, perceptions, thoughts, judgements, and the like, we can only understand the meanings of such words by thinking of them in terms of our own sensations, perceptions, thoughts, and judgements. Unless I were myself a creature of volitions I should find it an impossibility to understand what philosophers mean when they speak of volitions.

Every mind is, in this sense, a self-enclosed monad. And philosophy must take its rise for each of us, not in some generalized experience, but in the individual experience of each mind. We shall advance to a generalized experience later. The point is that we have to realize that it is later. We have to arrive at it as the result of a process.

This is the truth which underlay the famous method of Descartes. He realized that every philosophy must begin from the 1 and work outwards. But -unfortunately he at once became entangled in unjustified metaphysical assumptions about the nature of the ego and fallacious arguments about the external world. Because we begin with individual experience we are not to make any assumptions about the nature of personality nor of reality. The question which we are discussing is one of logical order and procedure. Our method must be to begin with the immediate data of the individual's experience, the given element in his knowledge, and working upwards from that basis, to attempt to see how the organized development of knowledge has arisen on that foundation. We shall assert nothing whatever about the metaphysical nature or status of the given element. We shall assert only that it is a logical ultimate, an absolute premiss to knowledge, at which therefore we must begin our inquiries and our arguments.

It will soon become evident, as our inquiry proceeds, that given certain elementary data to start with, the mind creates out of these materials the whole structure of knowledge. We have already had occasion in this chapter to observe the difference between the original data and later elaborations. We have remarked that an impersonal and Independent experience is not a datum; that the belief that your red is similar to my red is not a datum. These are later developments, the results of thought working upon its materials. And it will be part of our task to trace out how they arise.

Obviously our first step must be to sort out and separate the given elements of knowledge from the rest. If we are to begin with the data and proceed thereafter to the rest, we must first have a clear idea of what the data are. We can then make an attempt to see in what manner the mind builds on this foundation, and what principles govern its procedure.

Perhaps it will be objected that such a method is bound to have metaphysical implications, and that our hope of adopting a method without entangling ourselves in such implications is a vain one. But this objection misrepresents our hopes. No doubt it is true that every method has its implications. We neither can nor do we desire to escape that necessity. On the contrary, what we desire is to hit upon the right method, the correct beginning, and then to draw out what necessarily follows. Admittedly all depends upon the beginning and the method. That is an argument for beginning in the right place and proceeding in the right manner. It is not an argument against beginning at all. And if it were a valid objection to our method, it would be equally valid against any method whatever.

And where else can we begin except with the given element in the individual experience of each of us? Consider any piece of knowledge taken at random, for example, that Sirius has a companion star which is a 'white dwarf. Obviously this belief involves some general knowledge of astronomy, of the nature of double stars, of what is meant by ‘white dwarfs', &c. It is an elaborate mental product. Now we may be asked two relevant questions regarding this product; firstly, how it arose, and secondly, how it is justified. These are two separate problems, but they are intimately connected. To solve either of them we must necessarily go back in the last resort to such given and immediate mental elements as the sensations which we receive through starlight striking the eye, the sensations of the colour patches which constitute the spectrum, and the like. On such immediate sense data is all our astronomical knowledge built.

This is accurate, however, only for an astronomer. He may get knowledge direct from the colour bands of the spectrum. But those of us who are not astronomers and do not know how to handle the spectroscope cannot do this. Our knowledge that Sirius has a 'white dwarf companion is based upon the fact that the astronomer told us so, and that we think we have good reason to trust his opinion. In that case our knowledge goes back to the sound sensations which we received when we heard the astronomer lecture. Those sound sensations are among the data on which we built our knowledge. But the journey from the beginning in sound sensations to the end, i.e. belief in the 'white dwarf’ companion of Sirius, is a very long, difficult, and intricate one. For example, one of the stations through which we have to pass on the way is belief in the existence of another mind, that of the astronomer. But enough has been said to make it clear that, however we come by an astronomical belief, whether by our own researches or otherwise, the knowledge of each of us rests in the last resort upon the colour patches, sounds, and so forth, in his own experience.

It is not to be concluded that sensations are the only given elements of knowledge. That would be entirely false. They are, however, the most obvious of such elements and were taken for that reason as illustrations of our point. Our point was this. Whether the question before us be that of the historical origin and development of our knowledge, or that of its logical foundation, in either case we have to find the starting-point in the 'given'. How did our knowledge of the stars historically originate? From looking at the stars, i.e. from light sensations. What is the logical foundation of that knowledge? Again the light sensations from which all astronomical inferences arise.

Our method, then, will be to begin with an account of the given. This we shall attempt in the next chapter. We shall then endeavour to show by what steps knowledge has advanced beyond the given to something like its present state.

At once we shall be asked whether what we propose to trace out is the logical or the historical development of knowledge. For these, it will be said, are two very different things. It is one thing to inquire how the Greeks came to discover that the square on the hypotenuse of a right-angled triangle is equal to the sum of the squares on the other two sides. It is another thing to inquire how Pythagoras proved this proposition.

Our answer must be that we are concerned essentially with the logical development of knowledge, and that to unfold its history is not our business. That must be left to psychology, anthropology, or whatever is the appropriate empirical science. And yet we shall urge that the difference of the logical from the historical, however plain it is in theory, may be, and often is, exaggerated in practice. The two are in fact intertwined. The logical is in the last resort the marrow of the historical.

But postponing this latter point for later consideration, and concentrating for the moment only on the logical issue, we may say that our method will be as follows. We shall take our starting-point from the given. For the given can neither be explained nor disputed. It is there. And not even the most ingenious sophist can deny that it is there. He may dispute the existence of the world, or of the ego. But he cannot dispute the existence of the sensation of red when he has that sensation. This shows that the given is the logical foundation of knowledge, whatever may be its historical beginning. The given is what is certain in knowledge, what cannot be disputed. And it is immediate, not the result of a logical process. It is therefore the only possible logical foundation of knowledge.

We shall next ask ourselves what can be deduced from the beginning. Granted that the given is certain (whatever the given may be), what is the next step? What are the inferences by which, one after another, we build up and justify the elaborate structure of knowledge?

The Mental Constructions of External World

It will be seen that our method is the same as that of Descartes. But unfortunately Descartes took as his ultimate certainty, his starting-point, what is anything but a primal certainty, the ego as a substance. And he proceeded at once to make deductions regarding the external world which were fallacious. His method was correct, and rested on the most fundamental insight in modern philosophy. His application of the method was a series of blunders from the very outset.

We shall take as our beginning not the ego, but the given. I see a green patch before me. A foundation of knowledge, an indisputable certainty, is this simple experience of the green patch. Not the ego which is supposed to experience it, but the experience itself.

But what about the steps which are to follow? Descartes assumed that they must all be logical inferences. Now one of the first lessons which we shall learn is that from the given nothing about the external world can be inferred. (We can infer, I believe, something about the existence of other minds and their contents. But I am now speaking only of our knowledge of the external world.) Certain elementary acts of abstraction and conception, which we shall call 'the concepts of the given', will be found to be logically possible. But they will amount only to the classification of what is given. They merely enable us to arrange the elements of the given in helpful patterns. They do not enable us to advance to any kind of objective existence superior to the bare given. We cannot, for example, advance by any process of inference from the bare momentary experience of the green patch to the belief in the independent existence of a permanent external green object. We shall find, if we rely on logical inference alone, that we can never reach that point. We shall find ourselves shut up, each within his own private world of phantasms, and unable to get out of it. The wonderful fabric of knowledge can never, as Descartes thought it could, be built up in that way. By his method of inferences we shall begin with the given, and shall stay there for ever. We shall find that any inferences which have been supposed to lead from the private given to the public world of science and knowledge are utterly fallacious.

Shall we then conclude that our method is wrong? Shall we conclude that the mind has not actually started from the private experience of each individual and worked outwards? Shall we throw this overboard and hunt about for some other starting-point and method? By no means. For we shall find that there are other logical steps possible besides inferences, namely, mental constructions. We shall see that these mental constructions are the great instrument by means of which knowledge has advanced from its starting-point to its present state. It will be found that logical inferences are apt to be subordinate to them, to be no more than a means of co-ordinating our constructions, of ensuring that they are consistent with themselves and with one another.

That constructions are common in the higher reaches of science has long been suspected. That they permeate all knowledge, even in its most rudimentary stages, that no ordered world of any kind would be possible without them — this, I think, has not yet been realized.

We cannot yet say what is the logical nature of construction. Nor is it possible at this stage to solve the all- important problem of what is the criterion by which a true construction is distinguished from a false one, or to know what constructions can legitimately be embodied in knowledge and what cannot. These are matters for our future study. But glancing ahead from our beginning we may say this: we shall not expect to advance from the bare given even to the common belief in an external world, in the existence of objects, without the use of logical constructions which are quite other than inferences. We shall find that the material which is given to the mind is surprisingly meagre, and that out of this material it has built, by means of constructions, the entire universe.

It was because he did not understand this that Descartes failed. He could not advance one step from his beginning by legitimate inferences. And so, since he was unaware of the mind's use of imaginative constructions, he at- tempted to advance by means of illegitimate inferences, fallacies.

And yet what we are to study will be primarily the logical nature of the procedure of the mind, not merely its psychological development in time. For the construction, though it is to be sharply distinguished from inference, yet has its own logical structure, which we shall have to study. We shall begin at the logical beginning, the given. We shall attempt to advance to belief in an independent external world. We shall detail the steps by which this advance is made, and shall find that they are constructions; although, when once constructions are set up, inferences from them and between them come into play. We shall attempt to follow the mind further in its journey, beyond the common belief in an external world to more advanced scientific 'and philosophical knowledge. And we shall hope that by these means light will be thrown both upon the nature and structure of knowledge and upon its validity.

We have stressed the logical character of the mind-process which we are about to study and have distinguished it sharply from psychological and historical development. This is essential to our purpose. And yet it must be recognized that the historical is in many cases based upon and follows the logical. We must believe that in such cases each mind actually in some sense goes through all the logical stages required to arrive at a belief, though this process is implicit, unconscious. This assertion seems to require both explanation and defence; which I will now do my best to give it.

If we are asked, 'Why do we believe that there is an external world?' the question may have two meanings. It may mean 'What valid reason is there to believe it?' The question then concerns the logical steps which justify the belief. Or it may mean 'What is the psychological history of the belief?' Now what I wish to assert is that the psycho- logical way in which a belief is actually reached is often identical with the logical way (notwithstanding that the two aspects are rightly distinguished), or in other words that the mind has actually arrived at its belief by a process of reasoning which is identical with that which it would adopt if it had to justify its belief.
This is not always true. For example the Greeks may have known empirically the truth of the theorem of Pythagoras before Pythagoras dis- covered its logical proof. But in many important cases, and especially in the kind of cases we shall be dealing with in the next few chapters, it appears to me to be true.

How do I know that the world is round? Because the astronomer says so. This is clearly an account primarily of the psychological origin of my belief. And yet, assuming that I do not know enough science to understand the astronomer's reasons, his authority becomes validly my reason. I argue, 'The astronomer is a clever fellow who understands these matters. He says the world, is round. Therefore that is probably true, and I will believe it.' This is a perfectly sound logical justification of my belief so far as it goes, though it does not carry certainty. Thus the answer, 'because the astronomer says so' really gives both the logical and the psychological origins of my belief. They are in this case identical.

Similarly the answer which we give to such a question as 'Why do we believe in an external world?' is likely to combine both the logical and the historical aspects. ……… No one except a philosopher has ever explicitly asked and attempted to answer the question why we believe in an external world. The plain man will probably think the question simply silly. Yet the logical train of thought which the philosopher makes explicit may well be precisely that which has lain, deeply buried, in the subconscious mind of the race these many ages. I believe that, in a sense, mind developing from its animal to its human stage must actually have gone through the reasonings and arguments, the inferences and constructions. ……. The primitive savage or half animal mind must have had these mental processes unconsciously within it. But it was not aware of them. It had not the brains to understand its own thought.

It is no longer possible to believe in a complete hiatus between the mind of the animal and the mind of man. If we accept the theory of evolution we have to believe that the one shades off into the other. That reason is the exclusive possession of man, that there are no beginnings ot it to be found in the animal mind, is itself an irrational view to put forward. ……. Reasoning is implicit, unconscious, in the animal mind. It has become partially explicit and conscious of itself in man, so that reasonings which previously went on in the darkness have now emerged into the full light of consciousness. This is the same as saying that the essential advance of man on the animal consists not in his rationality but in his self-consciousness.

Reason in the animal world is not a rare exception. It is not a question of hunting out marvellous stories of unusual animal sagacity. Unconscious reasoning takes place in the daily operations of the lives of at least the higher animals, as for example in their acts of vision. The brute recognizes objects by sight. It also sees things at a distance and judges the distance for the purposes ol a spring, or to regulate its movements. But the operations of sight are well known to involve trains of logical operations. Both recognition of objects and judgement of distances necessitate inferences which are often wrongly drawn, so that the organism makes a mistake of some kind. The mistake is not in the immediate apprehension, but in the inference from it. The mind of the brute therefore argues and infers. But the brute is not aware of its own reasonings. The reasoning is implicit, unconscious.

There is nothing remarkable in this. We can trace in ourselves innumerable unconscious reasoning processes similar to those which we assert in the brute. Human beings, though capable of conscious and explicit reasoning, also reason unconsciously. We do so in the phenomena of vision. We do so in all the manifold trifles and details of daily life. From the faintest flicker of the eyelid of our friend we infer that he is angry or hurt. But we may have seen the flicker of the eyelid without noticing it, and have made the inference without being aware pf it. Unconscious reasonings are frequently mistaken by the credulous for 'intuitions', and are then regarded with great awe. And this mistake is the foundation stone of much muddled philosophical thinking and of whole systems of erroneous philosophy.

The reader will be aware of the controversy as to whether we come to know the existence of minds other than our own by direct apprehension or by inference from bodily behaviour. Without at the present stage going into the merits of the dispute (which we shall have to do after-wards), one can see that those who believe in inference from bodily behaviour must refer to unconscious- and implicit inference. No one supposes that the human child, growing out of infancy, solemnly and consciously goes through the steps of an argument by analogy before coming to the conclusion that his mother is alive and conscious. The reasoning, in all save philosophers, is unconscious and instinctive. But it is perfectly reasonable to hold that the argument by analogy from human behaviour is not only the logical justification of our belief in the existence of other minds, but is also its psychological source. In fact if we rule out the theory of direct apprehension, no other psychological source except an unconscious inference seems possible, and we are compelled to think that the oft-described argument by analogy from bodily behaviour is actually, though unconsciously, gone through by every mind as it develops. I am not trying to pre-judge the issue as to how we discover other minds. I am merely trying to show that unconscious reasoning in the matter must always have been believed in by those philosophers who accepted the usual inferential theory, and that it is not, therefore, a revolutionary or novel suggestion.

The aim of this discussion has been to show that although the distinction between logical and historical order is a real and important one, yet they do not always lie apart, but quite frequently coincide. Logic is the soul of history. And much that has just been said of our knowledge of other minds may very well be true also of our knowledge, of the external world. In the following chapters we shall attempt to trace out the logical steps by which the mind, starting from what is given, arrives at and justifies its belief in an external world. But this logical process may be also the psychological history of our beliefs. The individual and the race may actually reach this belief by passing subconsciously through these stages of argument. It so, the process of the child-mind in infancy will be not unlike the development of the embryo which, in the womb, traverses the stages of earlier evolution. What we shall lay down here, therefore, is not a set of barren sophisms, the solution of idle academic puzzles. It is the process of thought which the human race, and every individual mind, must actually have pursued. It claims to be not the ingenious logic-chopping of an idle philosopher, but the laying bare of the living tissue of human thought, the ideal history of the human mind.

As already stated, the progress from the given to belief in an external world will not be found to be a series ot inferences, but a series of mental constructions. The adoption of this view will cut out the appeal to primitive belief and 'instinctive belief which is relied upon by some realist writers. They perceive that our belief in an external world cannot be justified by any valid inference from what is given in consciousness. They are unwilling to subscribe to the view that it must therefore be a mental construction. And as they can accordingly give no rational account of it whatever, or show it as the result of a logical process of any kind, they are compelled to set it down as primordial, given from the beginning, and call it an instinctive or primitive belief. But this is mere mystery-mongering. A primitive belief is no more than a belief which we have held for a long time, and it may as likely as not be false. Nor is it reasonable to point to instinct as a source of our opinions in such matters. An instinct is some kind of tendency to action directed perhaps towards an end which is not realized in consciousness. It is impossible to see how it can be a valid source of any beliefs except perhaps blind prejudices. At any rate to justify one's beliefs by an appeal to instinct does not seem to be a course which either science or logic could approve.

It is an ancient and sound insight that we can have no knowledge of the outside physical world save through the physical senses, that there is nothing in mind which was not in sense. It is true that mystics claim to have knowledge of divine things by the medium of some kind of super-sensuous intuition. But no one has yet claimed that we have knowledge of chairs and tables through such a source. And if it is admitted, as surely it must be, that our knowledge of the external world can only come to us through sense, or through what the mind makes out of sense-material, then everything we believe about the external world must be either (1) a mental report of what is directly given, or (2) an abstraction from what is given, or (3) an inference from what is given, or (4) a mental construction.

Those who appeal to primitive belief must argue as follows: 'Our belief in an external world is not a mere report of the given. It is not a mere abstraction. For the 'object' is not a common element in the sensuously given, but something more than is given, something which lies behind the given as its supposed cause or ground. Nor is it an inference from the given. For it is generally admitted that all such inferences are invalid. Therefore it must be a belief of mysterious origin, a primitive or instinctive belief, of which no further account can be given, and of which no logical justification is possible'. But this is no more than the unphilosophical appeal to intuition. In opposition to this, our argument will be as follows: 'Our belief in the external world is not a mere report of the given. It is not an abstraction nor an inference. Therefore there is only one thing it can be, namely, a mental construction.'

We can cut away appeal to 'primitive belief and 'intuition' by the application of Occam's razor. Why, when we can give a rational and logical account of a belief as a mental construction, need we assume these mystical sources?

We have spoken here chiefly of our belief in an external world. That is the first problem we shall have to face, and perhaps it is the most difficult. But it is far from being the only problem. We begin with the bare given. We pass from this by a somewhat difficult passage to belief in an independent external world, the common world of objects, 'things', &c. From that we shall have to pass on to the more advanced knowledge contained in science. But the method which we have outlined will cover our investigations in the whole field of knowledge. All truth, all knowledge, we shall find, takes its origin from the given, is built thereon as a fabric of interwoven constructions, inferences, and abstractions. The constructional element in especial will be &und to permeate all knowledge from the bottom to the top.

Our method is empirical, and the philosophy to be expected in these pages will be an empirical philosophy, in accordance with the English tradition.

In medical science the word 'empirical' is loosely used as importing knowledge gathered from experience without any understanding of underlying causes. It is then opposed to 'deductive'. But for us the word 'empirical' is opposed, not to deductive, but to 'transcendental'. I mean by empirical that which does not attempt to transcend the bounds of experience. I mean by transcendental that which does attempt to do so.

Geometry, although it is wholly deductive, is an empirical science because it takes from experience its subject matter — spatial magnitudes and figures — without question. But a branch of knowledge which sought to get behind the space which we experience and to explain it as a form of our perception, or as the self-limitation of an infinite mind, would be transcendental.

Epistemology is an empirical science on a par with biology. Biology examines the structure of the organism, and the functions of its parts. Epistemology will examine the structure and functions of knowledge in an exactly similar spirit. But the essential point in which its empirical character comes out is this. It takes the data of experience — colour patches, sounds, and other sense" data — for granted without seeking to inquire into their transcendental origins. I am now seeing a green patch. That is for epistemology an ultimate fact. Epistemology does not seek to know, as a transcendental philosophy would, how and why the data of sense have arisen, whether, for example, they are the projections of a cosmic mind into individual experiences (whatever that may mean), or whether they are the results of 'divine imagining'. It does not seek to know whether the existence of the green patch which I am now seeing is rational, or can be deduced from the Idea of the Good. It simply takes the green patch for granted as a fact.

It is a common mistake to suppose that an empirical philosophy and a transcendental philosophy necessarily contradict one another. This is not so, although it is true that they are apt to be somewhat opposed in spirit. They might perfectly well exist side by side. They do not usually contradict one another because they are not on the same ground. They are concerned with different problems. There is nothing in Kant's 'transcendental aesthetic' which contradicts anything in geometry, mechanics, or any other science which deals with space or time. Or at least this was true in Kant's time. And if the reader happens to believe, with Hegel, that the world of sense issued out of the womb of an Absolute which consists of pure thought, or if he believes with Plato that it is a copy of the world of forms, there will be nothing in this book with which he need necessarily quarrel. Our empirical philosophy simply does not deal with these problems. It takes the world of sense, or at least the sense data, the colour patches, sounds, &c, out of which the world of sense is constructed, as ultimate facts of experience, and does not seek to go behind them.

To speak as yet of the given, then, assuming that there is one given for us all, is to go ahead much too fast It jumps at least two steps. The first is the step to the belief that our givens are similar. The second is the step constituted by the abstract concept based on this similarity as common quality of the many givens. We have to begin at the beginning. And the beginning for me is my given.

It would be pedantic, however, to proceed from this point exclusively in the first person singular. And I shall not hesitate to speak, as is ordinarily done, of the given; just as we, who no longer believe in the daily revolution of the sun round the earth, still speak of the sunrise. The reader will bear in mind that this is no more than a convenience of speech, and that the actual starting-point which we are discussing in this chapter is the particular given of a particular individual, i.e. what each of us will call my given. It will also be understood that in speaking of the given we are making no illicit assumptions regarding the similarity of our different givens, a question which we shall have to discuss later.

The word given presents an ambiguity which we must first of all clear up. It may mean either the metaphysical given or the logical given. The former is the given as conceived by Kant, who supposed that the matter of the object is given from the outside, from the side of the thing-in-itself, while the form is contributed by mind. This meaning rests upon and implies the dualism of mind and object In this sense given means something which is metaphysically different from mind, essentially non-mental, literally ‘given’ to the mind as a present from an outside source.

Here, in our present study, we must clear our minds of any such metaphysical presuppositions and theories. Not that it is our business to declare them false or in any way to adjudicate on them. We are not concerned with that. They may, for all we know, be either false or true. All we have to say about them here is that they are no proper starting-point for philosophy; that they are not involved in our conception of the given; and that if our method of beginning with the given caused us unwarily to entangle ourselves in any such assumptions, we should inevitably suffer the fate of Descartes, whose very first steps from his beginning were fallacious.

The given for us does not imply any metaphysical theory as to its own status. We are to consider, not the metaphysical given of Kant, but the logical given. By the logical given is meant anything that is necessarily taken as given or granted, as logically ultimate and indisputable, in an argument; that which we cannot doubt because we cannot go behind it; that which possesses primitive and absolute certainty, and which is therefore the necessary logical beginning of argument.

Perhaps we might successfully hit off the difference between the metaphysical and the logical givens by saying that the former is given in the sense of presented' or 'gifted'; while the latter is given in the sense of 'granted in argument'. A gift or present is something not originally mine, but handed over to me from the outside. And this idea is stressed in the metaphysical given, while it is entirely irrelevant to the logical given.

A little later on we shall find ourselves in agreement with Kant to the extent that we shall assert that the given is passive, while the mind's dealing with it is active. But this is a subsequent empirical observation which is in no sense implied in our conception of the given as such. It is not part of, or implied in, the definition of the given. We are not as yet concerned with it. As for Kant's view that the given is given from the outside, from the external thing-in-itself, any such idea is quite foreign to our philosophy. For us, on the contrary, the externality of the given is not something aboriginally 'there', on which the mind works, but something which is itself constructed by mind. This will appear in the sequel.

The most obvious given elements of experience consist in images or presentations. My awareness of red is an ultimate indisputable fact. I may interpret it as a red flower or as a danger signal or in various other ways I may explain it on idealistic or on materialistic theories These interpretations and these explanations, because they go beyond the given, may all be erroneous. They depend on inferences which may be mistakenly drawn But the given element itself, the bare awareness of red, is a tact about which there can be no mistake or dispute. It is a true datum or beginning.

Presentations may or may not arise specifically from the senses. The sensation of red colour may be received through the eye, or it may be part of a dream image or hallucination. It is important to understand that the images of hallucination and dream are just as much part of the given as are sense presentations. There does not in fact, appear to be any intrinsic difference between a dream image and what we afterwards learn to call an image of physical reality. Any suggestion that we can distinguish the dream image by its being paler, less vivid, or less clear, is quite illusory. The difference is extrinsic, residing in the relations of the image with contiguous experience. We classify one image as real the other as unreal according to the nature of these extrinsic relations. This classification involves concepts, and is therefore not given.
Hence under the general heading of presentations or images I include (1) all sense presentations, colours, sounds, odours, tastes, smells, muscular sensations, &c.; (2) all images of hallucination, dream, illusion, or memory' which have the same immediate or given character as sense presentations.

By presentations we are not, of course, to understand objects whether objects in dream or in reality. The inkpot before me is not a presentation. It is a complex of presentations, concepts, and ideal constructions. We do not arrive at objects until a much later stage in our philosophizing. Objects are not given. We are at present at the very beginning of our thinking, and have got no further than colour patches, disconnected sounds, and the like.

It will serve to illustrate the extreme meagreness of the given if we consider in a little detail what any one of the senses actually gives us. We will choose for this purpose the sense of sight, because sight undoubtedly supplies normal people with more of the raw material of knowledge than any other sense. It is the least meagre source of the given. And it is also the sense which is most easily ob- served and understood by most of us.

What, we actually see, then, is nothing except moving and changing patches of colour. It is disputed whether or not these colour patches are flat and two-dimensional, so that the third or depth dimension has afterwards to be discovered or constructed. Since Berkeley's time the most common opinion has been that sight by itself gives only a flat plane. Some more recent writers, however, have attempted to prove otherwise. They think that depth is immediately given. This attempt has been, in my opinion, without success, and I shall adopt the opinion of Berkeley on this matter. But I do not wish to interrupt the discussion of the given at this point by a controversial argument, and I shall therefore postpone the full discussion of the question till we reach the chapter on space and time. For the present I shall assume as true the opinion that the visual given is flat and without depth.

There being no depth, the colour patches do not lie at a distance from us out in space, but appear to lie right up against the eyes. Strictly speaking this is inaccurate because it implies that the mind distinguishes what is close up against the eyes from what is far away, i.e. that it has a sense of depth. What is really intended, however, is that the mind at this stage has no sense of depth at all. It is aware of the colour patches, but is not aware that they lie at any distance, either small or great, out in space.

The mind constructs depth and distance. And long practice and experience enable us to read them into what we see, so that they appear as if they were given- But if we leave aside these results of mental elaboration, we find that all sight actually presents us with is a world like a picture, flat without depth.

It will be evident that the given of sight includes both extension-spread and duration-spread. But this is very far from saying that it includes space and time. It will be well to make this distinction clear. In the first place the extension-spread which is part of the given is two-dimensional only. It only exists, moreover, within the visual field of our colour patches. It does not extend away in- definitely beyond the immediately presented experience. It is bounded by what we see at the moment. Infinite or indefinitely continued space is a later construction.

It is also most important to notice that empty space is not given. Empty space cannot be sensed. It is a mental construction. It involves three dimensions, and it also involves the extension of space beyond the colour field. If it be suggested that a two-dimensional empty space can be sensed as that which intervenes between two colours on the flat surface of the given, the suggestion will be negatived by a moment's thought. What intervenes between two colours is invariably another colour. Up against the wall of my study are two tables several feet apart. The sophisticated mind believes that there is empty space between the two tables. But all that can actually be seen between them is the colour of the wall behind them. And the colour of the wall is not seen as behind them, but as lying in the same flat plane as that in which they lie. Between the stars we see the blue-black colour of the sky. Black colour is no doubt the mere absence of light. But it appears in consciousness as a positive colour sensation. The space between the stars is not seen as empty space, but as a flat blue-black surface.

Spatial shape, so far as it is two-dimensional, i.e. outline, is given. For the colour patches have outline. But the extension-spread of the given has absolutely no geometry. The elaboration of geometry is a long subsequent operation of the abstracting mind. Even our description of extension-spread as two-dimensional is inaccurate. For its two dimensions are the result of sophistication. They belong to our view of the given, not to the given itself. The given has nothing more than undefined spread. This spread is in all directions on the flat surface. The conception of two directions at right angles to one another, serving as co-ordinates for measurements, is the result of later analysis and thought. And the same is true of all geometrical conceptions.

The colour patches change. They move from side to side. They pass out of the field of vision altogether. They flicker, fade, grow brighter or darker, appear and dis- appear, increase or decrease in size. These changes we afterwards interpret as due to various causes. We think that the movement of the patches from left to right, and then their disappearance outside the edge of the field of vision, is due to our turning our heads round. Or we explain the decrease in size of the patch as due to its receding from us into the distance. Or we think that the change in outline of one of the patches is due to some other object intervening between us and it, and cutting part of it off from view. But all these explanations belong to the stage of sophisticated thought. They are not given. For we have before us not objects, but only the colour patches. None of these explanations of the changes of the colour patches could possibly occur to the aboriginal mind moving exclusively on the level of the given (supposing that such a mind could exist). To such a mind there could be no such thing as a head to be turned round. For there would be no objects. Our bodies are not given to us as bodies. They are merely part of the kaleidoscope of colours which we sense. And they are not, except after considerable experience of movement, specially connected with ourselves. My hand lies on the table in front of me. No grounds are given for supposing that this pinkish colour patch, which I afterwards come to interpret as my hand, is part of me. Afterwards, for a variety of reasons later to be examined, I come to regard it as specially attached to me, as part of 'my' body. But this is a result of thought and experience. It is not a beginning not a given. The hand is originally merely an indifferent part of the colour world which floats chaotically around me. It might as well be regarded as part of the table on which it lies. Nor again could the aboriginal mind explain the decrease m the size of a colour patch as due to its receding from him For the idea of depth, or spatial distance along the line of vision, has as yet no existence.

The movements and changes of the colour patches make it clear that the given has duration-spread, and that the relation of 'before and after' is given. This duration spread stands to the developed conception of time in much the same relation as the rudimentary extension-spread of the colour patches stands to the developed conception of space. Duration-spread is not the 'even flow' of Newton any more than extension-spread is the space of Euclid. Duration-spread is not infinite and endless. There is no empty time, and no future time, in the given. The future is clearly an expectation which arises only as a result of reflection on the present and the past.

Enough has been said to indicate the general character of the given of sight. Similar accounts might be written tor the other senses. From hearing we receive a medley of sound patches. They have no extension-spread, but they have duration-spread, and exhibit such temporal relations as before and after and 'between'.

Touch is, of course, a most important sense in the development of spatial concepts. Passing one's hand over a flat surface gives rise to both tactile duration-spread and extension-spread. The genuineness of the extension has been doubted. It has been thought that the extensional parts must be successive, or in other words that tactile space must be simply time. But recent psychology of the blind shows that this is a mistake.

The formal relations to which extension- and duration- spread give rise, such as 'between', 'before and after', &c., are given. All the elementary and primitive spatial and temporal relations are given.

Thus it would be a mistake to suppose that presentations and images make up the whole of the given. It also includes relations of various kinds. The most important are (1) relations of position in the extension-spread, such as ‘to the left of’, 'between', and the like; (2) relations of position in the duration-spread, such as 'before and after’; and (3) the profoundly important relations of resemblance and its opposite. But this does not profess to be a complete list of given relations.

It is sometimes supposed that all relations are in some special sense the work of thought and cannot, therefore, be given The given is in that case conceived as the bare and utterly formless matter of sensation Form is supposed to be contributed by mind, and includes relations. This is the Kantian standpoint. It may or may not be legitimate. But I only mention it here in order by excluding it from our discussion as irrelevant, to avoid confusion in our thinking. To introduce it here as an objection to our view that some relations are given would be to confuse the metaphysical with the logical given, and completely to fog the issue. Relations may, for all I know to the contrary be the creation of a cosmic and transcendental mind, in that case they are doubtless not part of the metaphysical given, i.e. of that which is supposed to be contributed from outside the mind by the thing itself. But they are still part of the logical given with which we are here concerned. For they are still ultimate primordial facts of our experience which we cannot get behind and which stand logically at the beginning of all inquiry as premisses. The same distinction must be made, not only for relations but also for space and time, and even for presentations themselves. Even if we were to admit with Kant that space and time are the work of mind, and so not metaphysically given, yet extension-spread and duration-spread are none the less logically ultimate in our experience, and belong to the logical given. Again, colour patches and images generally have been held by some philosophers, such as Berkeley, to be subjective 'ideas'. But those who hold this view need not deny that such presentations are logical givens. Thus in general the various phases of the idealist-realist controversy do not concern us in our present discussion, and can be left out of account as having no bearing upon our statement that some relations are given.

It will be noted that I say only some relations. For it is not asserted that all relations are given. Some are undoubtedly mental constructions or the results of such constructions. Such, for example, is the relation of substance and accident, the construction of which we shall discuss on a later page.

If two colour patches in the given are both red, then the relation of resemblance between them is also given. So is the relation of unlikeness between a red and a green, or in general any relations of likeness and unlikeness. It is sometimes said that resemblance is dependent upon the comparison of two presentations, and that comparison involves a comparing mind. But this only means that in order to notice the resemblance a mind is necessary. And the same is true of the bare presentations themselves. In order to become aware of the resemblance a comparing mind is no doubt necessary. In order to become aware of red colour a perceiving mind is necessary. No doubt only minds can be aware either of presentations or resemblance relations. But the relation, like the presentation, is given.

We have spoken so far only of that kind of given which later becomes the basis of our knowledge of the external world. This consists of sense presentations, what we may call physical relations, &c. It must not be overlooked, however, that we possess knowledge of the internal world of the self, and that this knowledge must also take its start in a given of some kind. The greater part of our knowledge, whether in history, science, art, or any other branch, is concerned with the external world. The immense preponderance of human knowledge looks outward. All the sciences, except psychology, the most junior of them all, have portions of the external world for subject-matter. I suppose that at least ninety-nine out of every hundred articles in the Encyclopaedia Britannica deal with things in the external world. Only a few scattered psychological or philosophical articles deal with mind.

It is perhaps natural in these circumstances that a theory of knowledge should have a tendency to dwell on our knowledge of the external world more than on self- knowledge. Yet we cannot ignore the latter. Not only has it its legitimate place in knowledge, but, as we shall see, it is interwoven with knowledge of the external world in such a manner that the latter would be impossible without it. Knowledges of the outer and inner worlds are interdependent. We must therefore inquire what is the starting-point of self-knowledge, what is the given on which it is based.

It must be made clear at the outset that the ego, conceived as some kind of transcendental unity, is not given. As Hume long ago observed, when we look into ourselves we perceive volitions, emotions, ideas, and the like, but never the I which has them. It is no part of our intention in this chapter to discuss metaphysical theories of the nature of the self. But what we have to note regarding all such theories is that the knowledge which they purport to contain is always derivative, never given. These theories are philosophical constructions of the sophisticated mind. They are never pure reports of the given.

The internal given, then, does not include any pure ego. But it includes all the acts of what has been called the empirical mind. I become aware of myself by becoming aware of my activities such as thinking and feeling. And the sense of the I as distinguished from the not-I is based upon the perception of myself as active in contradistinction from the not-I as passive. The distinction between active and passive is the fundamental basis of the division of the world into internal and external, mind and matter.

Suppose there could exist a mind, wholly innocent of sophistication, aware only of the fleeting images and presentations in the world of the given. Suppose it shut off from communication with other minds and unaware of their existence. Could such a mind become aware of itself? and if so, how? Now in the first place, according to the views here adopted, it could not be aware of the external world in the sense in which sophisticated knowledge is aware of it. It would see before it a phantasmagoria of moving colour patches. It would hear sounds and receive sensations from the other senses. It would not think that the colour patches continued existing when they disappeared from its own vision, or the sounds when they vanished from its hearing. It could have no possible reason to think so. It would therefore have no conception of a world independent of, and existing apart from, its own presentations. It would thus be living in a world of private dreams.

It might be argued that such a mind could not be aware of itself, since self-knowledge can only come into existence when the self is contrasted with the external world. But I do not think this view is correct. Knowledge of self does not depend on prior knowledge of the world as independent and external. On the contrary, as we shall see, knowledge of the world as independent and external depends immediately on our knowledge of other selves, and therefore ultimately on our knowledge of our own selves. And our self-knowledge depends on the contrast, not between mind and what is independent of mind, but between activity and passivity. Before me is the moving stream of colour patches, the private world of phantasms. The logically original act of consciousness is awareness of these, not of myself as a self. But what happens next? I am looking at a green patch. Growing tired of it I begin to look at the adjoining red patch. In doing so I have not only moved my eyes. I have also performed what must be regarded as my first conscious act. I have focused attention first on one thing, then on another. After this, perhaps, I notice the resemblance between a number of different red patches. I thereupon form the concept 'red'. This again is an activity, the activity of abstraction and conception. Next, I find that I dislike one presentation and desire another. Emotional and volitional activities come into being and are noticed.

It is these activities of the mind which form the given on which all self-knowledge is based. And it is important to realize that they are ultimate unanalysable data, genuine" starting-points, in the same sense as presentations. Just as the red colour before my eyes is an ultimate fact of consciousness, so the acts of mind, attention, conception, willing, &c, are ultimate facts of consciousness. The science of psychology, or any other possible knowledge of mind by itself, starts from these as a basis, as an ultimate premiss, just as all physical sciences start from the basis of physical sensations as their ultimate premisses.

When we regard the activities of mind as given, we are of course taking them as objects. The mind thinks. And it can also watch itself thinking. It is when it makes its actions the objects of its attention that they are apprehending as being 'there', as given.

As contrasted with its activity in conception, judgement, attention, volition, the mind is, in pure sense presentation, wholly passive. The green patch lies in front of me. It is there. Its being there is no act of mine. I do nothing to make it appear. I am not, as a rule, even aware when it is going to appear. When it does appear I merely accept it. I am purely receptive of its appearance. No doubt an act of mental attention is involved in continued perception, as also a whole series of muscular activities which centre on the object. But these activities are easily distinguished from the content of the sensation itself. The attention is an activity which falls on my side. The green colour itself is not an activity, and falls therefore, on the side of the not-I.

The green patch, further, is independent of my consciousness in the sense that my consciousness does not control it. Its presence, its movements, its disappearance or replacement by a red patch, all these happen, or may happen, independently of me, independently of my wishes, thoughts, or feelings. They happen in my consciousness. This is a character of the not-I in general.

Thus the primitive world of the given divides itself into two halves, (1) what I do, the activities of my consciousness, and (2) what I suffer, what happens in my consciousness independently of me or of any of my activities. The latter cannot be attributed to 'me'. It is something distinct from me and my acts. The former is the world of the I, the latter the world of the not-I.

The world of the not-I is at this stage independent of mind in the sense just explained, i.e. as being not an act of the mind and not subject to its control. But it is not as yet independent in any other sense. That it 'exists' apart from the mind, that it goes on existing when the mind is not aware of it, or that it exists for other minds, such thoughts cannot emerge at this stage, and are much later developments.

It will be noted that the characters of the not-I which we have mentioned above belong as much to the presentations of dream or hallucination as they do to the presentations of sense. The dream-mountain is as passive and as inde- pendent of my conscious activities as is the 'real' mountain. The dream-mountain falls on the side of the not-I. It is only at a later stage that it is again distinguished from the presentations of 'reality' and is condemned as 'subjective'.

The independence of the given is only another aspect of its passivity. It is independent for the very reason that there is no sign of my activities in it. Hence the only element of distinction between the I and the not-I which is given at the start, the only distinction which is a datum, is that between activity and passivity. This distinction, I say, is itself given. For the mind is immediately aware of its own activities — thoughts, feelings, volitions — as activities. This active character of mental life is just as much immediately presented as is the redness of red. The absence of any such activity on the part of presentations constitutes an immediately given contrast, and causes the primitive world to fall at once into the two halves, the I and the not-I.

_ It will be well to notice that for the consciousness of the distinction between them to arise there is not necessary any recognition that the presentation is either 'mental' or 'non-mental', that it is 'inside' or 'outside' the mind; and that the application of such epithets to it is probably quite meaningless, and is certainly not implied in the idea of the not-I itself. Nothing is implied except passivity. That alone is the essence of the not-L Statements that the objects which we see and hear are 'mental' or are not 'mental', that they are 'outside' the mind or 'inside' it, that they are 'ideal' or Veal', are all of them mere metaphysical theories which we afterwards weave. They are not reports of the given. They have no part in the original world of the given which we are considering. They are constructed, and how they come to be constructed is part of our problem.

We may now sum up our conclusions. Our assumption — to be justified by the course of our inquiries — is that the mind starts from certain fundamental data, which we call the given, and that it builds upon these data the whole fabric of knowledge by means of constructions and inferences between constructions. It is thus essential to our method to get clear about our starting-point, to separate what is given from what is not given. What is not given we have then to explain as construction or inference.

The given falls into two parts, that part which lies at the basis of our knowledge of the external world, and that part which lies at the basis of our knowledge of ourselves. The latter consists of our own mental activities, such as knowing, thinking, willing, feeling, attending. The former includes (1) presentations, meaning thereby the images of sense, of dream, hallucination, or delusion, which have not as yet become differentiated and distinguished from one another; for the differences between them are not given, but subsequently elaborated. The given of the external world also includes (2) duration-spread and extension-spread, and (3) certain relations, not only those involved in duration-spread and extension-spread, but also such relations as resemblance.

As a general account of the given this must suffice for our purposes, though making no pretence at being exhaustive. But there are two supplementary observations which it seems desirable to make before we pass on. The first is to avoid a misunderstanding. It is not intended, of course, that pure awareness of the given, without any thought element whatever, is ever an actual psychological state of either man or animal. Such pure awareness is an abstraction. In every state of consciousness there must be at least some minimal conceptual element. Such a minimal thought element will be studied in the next chapter under the name of the concepts of the given. It is difficult to conceive of any actual consciousness which would not involve at least some vague recognition, not of course of objects, but of sensory elements such as colour. Such recognition will involve the concepts of the given, and will to that extent go beyond pure awareness, pure passivity. Our contention must be, therefore, firstly that pure awareness, though it never exists unalloyed, is nevertheless a distinguishable element in knowledge and is the logically prior element; and secondly, that the most primitive actual consciousness, though it must contain some implicit or unconscious conceptual element, will yet approximate to pure awareness, and will approximate the more closely to that limiting state the more primitive and undeveloped it is. So that something not very far removed from pure awareness must have been the historical as well as the logical beginning.

Our second observation concerns the relation of knowledge to action. The given is independent of the will. The red patch is red, and its being so is not the result of our conations or of any kind of mental activity on our part. We cannot by any act of will alter red to blue. Outside my window is a tropical garden. I cannot alter this to a London street by a mere wish. The given has the hardness and unyielding character which is attributed to fact. Pure given and pure fact are identical. The given is precisely that which exists prior to and independently of any activity of the mind. The utmost that the mind can do is to build the fabric of knowledge on it as a foundation. It is possible (and we shall see later that it is true) that the mind may have before it more than one alternative way in which it may construct the fabric of knowledge, and that it may choose at its pleasure or convenience between them. But the foundation of the given it cannot alter. It is there. Hence the extreme pragmatic view that knowledge has no function and no justification save that which it finds in action is not born out here at the starting-point of knowledge. This is sometimes expressed by saying that the pragmatic view fails to explain what is called fact In respect of what is given the mind is not free to apprehend what it likes. One can imagine circumstances in which the belief 'This is blue' might be much more useful than the belief 'This is red'. But if in fact the object is red we cannot accept the belief that it is blue, however useful it would be to do so. Knowledge in its more advanced stages may perhaps possess some measure of freedom. We have yet to discuss that question. But it is not free here at the beginning. Nor can it ever, even in its highest flights, shake itself free from the given, which it contradicts only at the risk of being false. Knowledge is everywhere tied to the given. That is a first principle of epistemology.

This principle applies not only to that elementary kind of knowledge which consists in mere reports of the given, such as 'This is red'. It is true of knowledge throughout. The most elaborate and advanced scientific hypothesis must agree with the facts. If such a hypothesis leads to the prediction 'A will be red', and in fact A turns out to be blue, then we shall have to amend or give up our hypothesis. What contradicts the given or anything that is inferred from the given cannot be true. It is in this sense that all knowledge, even the most advanced, is tied to the given.

W.T. Stace's "The Concepts Of The Given":
We take the concepts of the given (or 'Sensed Perception') to be the logically first kind of concepts. They are possible to the solitary mind which has no knowledge either of other minds or of a public external world of objects. They involve the smallest possible element of mental elaboration. They are the closest to bare awareness of the given. They involve no inferences, no hypotheses, no fictions, and no genuine world-building. The concepts of 'things' and objects ('categorized Perception' to us), which we meet with later, 'house', 'man', 'star', are logically subsequent to the concepts of the given, because (1) they involve concepts of the driven, and could not come into existence unless the perceptions had come into existence first; and because (2) they involve that the mind actually adds to the given by means of imaginative constructions.

William James' “A World of Pure Experience":
"the relations that connect experiences must themselves be experienced relations, and any kind of relation experienced must be accounted as real as anything else in the system".
"the parts of experience hold together from next to next by relations that are themselves parts of experience."

Russell's "V. THE KNOWLEDGE BY ACQUAINTANCE":
KNOWLEDGE BY ACQUAINTANCE AND KNOWLEDGE BY DESCRIPTION
There are two sorts of knowledge: knowledge of things, and knowledge of truths.
Knowledge of things by acquaintance is essentially simpler than any knowledge of truths, and logically independent of knowledge of truths.
Knowledge of things by description, on the contrary, always involves some knowledge of truths as its source and ground.

We shall say that we have acquaintance with anything of which we are directly aware, without the intermediary of any process of inference or any knowledge of truths. Thus in the presence of my table I am acquainted with the sense-data that make up the appearance of my table.

My knowledge of the table as a physical object, on the contrary, is not direct knowledge. My knowledge of the table is of the kind which we shall call ’knowledge by description’. The table is ‘the physical object which causes such-and-such sense-data’. In order to know anything at all about the table, we must know truths connecting it with things with which we have acquaintance” we must know that ‘such-and-such sense-data are caused by a physical object’. There is no state of mind in which we are directly aware of the table: all our knowledge of the table is really knowledge of truths, and the actual thing which is the table is not, strictly speaking, known to us at all. We know a description, and we know that there is just one object to which this description applies, though the object itself is not directly known to us. In such a case, we say that our knowledge of the object is knowledge by description.

In addition to our acquaintance with particular existing things, we also have acquaintance with what we shall call universals, that is to say, general ideas

Russell's "X. THE KNOWLEDGE OF UNIVERSALS BY ACQUAINTANCE":
It is obvious that we are acquainted with such universals as white, red, black, sweet, sour, loud, hard, etc,. i.e. with qualities which are exemplified in the sense-data. When we see a white patch, we are acquainted, in the first instance, with the particular patch; but by seeing many white patches, we easily learn to abstract the whiteness which they all have in common, and in learning to do this we are learning to be acquainted with whiteness. A similar process will make us acquainted with any other universals of the same sort. Universals of this sort may be called ‘sensible qualities’. They can be apprehended with less effort of abstraction than any others, and they seem less removed from particulars that other universals are.
We come next to relations. The easiest relations to apprehend are those which hold between the different parts of a single complex sense-datum. For example, I can see at a glance the whole of the page on which I am writing; thus the whole page is included in one sense-datum. But I perceive that some parts of the page are to the left of other parts, and some parts are above other parts. The process of abstraction in this case seems to proceed somewhat as follows: I see successively a number of sense-data in which one part is to the left of another; I perceive, as in the case of different white patches, that all these sense-data have something in common, and by abstraction I find that what they have in common is a certain relation between the parts, namely the relation which I call ‘being to the left of’. In this way I become acquainted with the universal relation.
In like manner I become aware of the relation of before and after in time. .....
Another relation with which we become acquainted in much the same way is resemblance.
KNOWLEDGE OF THINGS
Our immediate knowledge of things, which we called acquaintance, consists of two sorts, according as the things known are particulars or universals. Among particulars, we have acquaintance with sense-data and (probably) with ourselves. Among universals, there seems to be no principle by which we can decide which can be known by acquaintance, but it is clear that among those that can be so known are sensible qualities, relations of space and time, similarity, and certain abstract logical universals.

THE starting-point of knowledge is my given … which occupy consciousness within my self-enclosed ego. In order to advance to knowledge of a public external world, it is necessary for me to issue forth from the privacy of my own ego into communication with other minds. The solitary mind, without the co-operation of other minds can never come to the knowledge of an objective world' Its world will remain a private world of dreams. Hence the first great step forward towards knowledge is the substitution of a public external world for the private world of each ego.
But before this great step is taken, is any knowledge possible? Is it possible for the solitary mmd, shut up within itself, to elaborate even a rudiment- any kind of knowledge? If so, it is clearly necessary that we should describe such knowledge in its correct sequence. The question will be discussed in this chapter. And we shall find that such knowledge, elementary though it be, is logically possible. It consists in what we shall call the concepts of the given.

No knowledge whatever is possible without concepts. We are as yet far from the kind of knowledge which is embodied in scientific laws and generalizations. And we need not consider it here. Let us examine any of the most rudimentary pieces of knowledge we can come at, and we shall find it conceptual. Not only such elementary judgements as 'This is red' involve concepts, but even the bare recognition of sensations such as might be expressed by the ejaculatory 'Red' I is conceptual, since it involves the classification of sensations.

Conceptual thought is the instrument with which the mind works upon the given. The given in itself is a chaos of presentations and presented relations. This chaos the mind reduces to order by means of its concepts. The mind is the builder of the cosmos, and its bricks are the varied elements of the given.

….. We cannot say how or why the mind conceptualizes. That it does so is an ultimate fact. Conceptuality is the fundamental nature of thought which we find, and which we have to accept with 'natural piety'. All we can do is to begin at the beginning by studying first those concepts which form the logical starting-point of knowledge.

We must not be confused by the fact that the concept has two aspects, can be looked at in two different ways. It is the mind's instrument for dealing with the given. And it is also itself part of the given. We may view concepts along with volitions, feelings, emotions, &c, as the ultimate given elements of mental life. We are then looking at concepts from the outside and treating them as objects. Thus objectively viewed they are part of the given because they cannot be explained or analysed, but are ultimate data. But subjectively the concept is an instrument which the mind uses on the given. The concept sorts out the given and arranges it in order. And k may deal with itself as part of the given of mental life in this way. The psychologist classifies concepts. He is then using the concept (viewed as an instrument) to classify concepts (viewed as part of the given).

The logically first kind of concepts are what I shall call the concepts of the given. Let us remind ourselves that the mind at this earliest stage of its thinking is not confronted with objects or 'things'. It is confronted by the pure given, i.e. by sense-presentations, dream-images, hallucination-images, extension-spread, duration-spread, and a few relations. The 'thing' or object is as yet far ahead in the journey of knowledge. It has not yet been constructed.

The mind, therefore, cannot at this stage make to itself concepts of objects such as 'house', 'star', or 'man'. Much less can it generalize about houses, stars, and men. It has to begin with the concepts of sense-presentations, images, and the like. The earliest concepts are therefore concepts such as 'red', 'blue', 'loud', 'odour', 'between', 'after', 'bitter-tasting', &c. And these are what I call the concepts of the given.

No doubt such concepts are constructions in the sense that they involve the activity of the mind. They are actively thought, not passively given. But they are not constructions in the technical sense in which I propose to use that term in this book. We have not yet reached examples of genuine constructions. We shall meet them first in the mind's advance from its private dream-world to a public external world of objects. We shall then see that this advance involves a leap beyond the given. It involves an extension of the given beyond itself by means of constructs or fictions. The mind has to introduce elements which are not given. No such addition of new or invented matter is involved in the concepts of the given. They contain no element which is not itself given, except the activity of thought itself. We shall not call them constructions, therefore, and shall avoid the use of that word except in the technical sense later to be introduced.

All that is necessary for the coming into being of the concepts of the given is that the mind should notice the resemblances and differences which occur among the elements of the given. All concepts whatever are founded upon the fact of a resemblance. This is true even of the later and more advanced types of concept. But here we are concerned only with the concepts of the given. All that is involved in the concept 'red' is that the mind should notice the resemblance of two or more red patches, and should identify the red in them. How the mind does this is a question which cannot be asked. The fact that it does so is ultimate and unanalysable. It is itself given.

The reader (who is of course an acute logician) may object that it is possible to have concepts of classes with only one member to each class, or with no members at all; and that therefore the concept as such cannot be founded, as here suggested, on the resemblance of two or more things or appearances. 'Red elephant', for example, is a class with no members. 'Planet inhabited by men' may perhaps be, a class with only one member. But these are hair-splitting refinements of later thought. The original concepts of the mind could not have come into existence without the comparison of two similar things, and such comparison is the logical foundation of the concept. The concept 'red' could never have become separated from the sensuous perception of red, thought would never have emerged from sensation, without such comparison. If we have the concept of a class with only one member, this at least implies the possibility that there might be other members possessing the common characters of the class. Mathematicians insist that 0 is a number. But this number could never have been discovered unless there had been something in the world to count, something to give us the previous conceptions of the numbers 1, 2, 3 .... In the same way concepts of nil-classes or of singular classes presuppose classes of at least two members. Therefore the comparison of two or more presentations is the logical basis of concepts. If this is admitted we can proceed with the argument which the acute logician interrupted.

The red patches are given, and the relation of resemblance between them is given. And the concept 'red' contains nothing except these elements. There is nothing in this concept which the mind has assumed, or introduced out of its own stores. There is nothing except what has been actually seen, actually perceived by the senses. To arrive at the concept there is necessary, of course, the mental act of comparison. But the act of comparison does not involve that the mind in making the concept adds any element to the given, and then takes that addition to be a part, not of itself, but of the object. This occurs in the true 'constructs' of the mind which we shall study later, but not in the concepts of the given. These latter have nothing in them except what is itself given.

It is for this reason too that we take the concepts of the given to be the logically first kind of concepts. They are possible to the solitary mind which has no knowledge either of other minds or of a public external world of objects. They are the only kind of knowledge which is so possible, and therefore they constitute the beginning, the first step, of knowledge. They involve too the smallest possible element of mental elaboration. They are the closest to bare awareness of the given. They depart from it by a hair's breadth. They differ from such bare awareness only in being of the nature of thought, in being conceptual. But they involve no inferences, no hypotheses, no fictions, and no genuine world-building. The concepts of 'things' and objects which we meet with later, 'house', 'man', 'star', are logically subsequent to the concepts of the given, because (1) they involve concepts of the driven, and could not come into existence unless the concepts of the given had come into existence first; and because (2) they involve that the mind actually adds to the given by means of imaginative constructions.

Needless to say, concepts of sense-presentations are not the only kind of concepts of the given. In the first place, such a concept as 'red' might be derived as easily from the experiences of dream or hallucination as from the experience of what we afterwards come to call the real. Secondly, concepts of the given include concepts of those relations which are themselves given. 'Resemblance' is a concept of the given. So is 'unlikeness'. So again are such durational concepts as 'before' and * after', and such extensional concepts as 'beside', 'above', 'between', &c. (but 'between' is gathered both from duration-spread and from extension- spread). But we must be careful here not to fall into the mistake of supposing that these last-mentioned concepts are the advanced spatial and temporal concepts of geometers and mathematicians. Nothing like space or time has yet come on the scene. We have only extension-spread and duration-spread. We may see a red patch between two blue ones. When the same conjunction occurs again on another occasion, we compare the two experiences, and note the resemblances of the relations, and we have the concept 'between'. This does not involve a three-dimensional space, nor an empty space, nor a space extending beyond the actual field of presentations. Much less does it involve any recognizable geometry.

Not only concepts of particular qualitative presentations, such as 'red', 'loud', 'sweet’ , fall under the head of the concepts of the given, but even more general concepts such as 'colour', 'sound', 'odour', 'taste', 'sensation'. This may at first sight seem surprising. For it is customary to arrange concepts like a pyramid, the less general at the bottom, the more general at the top. Arranged in this way, we should have 'red', 'green', 'blue', 'bitter', at the bottom, and the general concepts 'colour', 'taste', 'smell', above these. And still higher in the pyramid above 'colour' and 'taste', would come the even more general concept of 'sensation'. It might seem, then, that the more general concepts are farther away from the given than the less general ones, and should not be lumped together with them, but should be made to constitute a second stage, a later advance, in knowledge.

There is no objection to counting two stages instead of one, if the reader so desires. I shall allow him to arrange his concepts in pyramids or any other pretty figure that takes his fancy. But it still remains true that the so-called higher concepts, the more general ones which are placed high up in the pyramid, may still be concepts of the given in the sense here defined. Any concept is a concept of the given if it can be formed direct, without any intermediate steps, from a comparison of two or more elements of the given. There is nothing in such concepts beyond what is given, except the mental act of comparison. There is no hypothesis, assumption, or other addition by the mind to the given. The mind observes two red patches, observes the resemblance of red to red, and frames the concept 'red'. The mind observes two patches, one red, the other green. It notes a certain resemblance between them, a common something which binds them together and distinguishes them from sounds, tastes, &c, and so frames the concept 'colour'. There is nothing in this concept except the given resemblance. Moreover the concept is formed directly from the experience of the given without any intermediate logical steps. The concept 'colour' is not dependent, as the pyramid theory is apt to assume, on the more specific concepts such as 'red' and 'green'. To prove this, we will consider a mind confronted by a 'number of colour patches no two of which are of the same colour, a mind whose experience is entirely limited to one red, one green, and one blue patch. Such a mind would have difficulty in framing the concepts 'red', 'green', and 'blue', because to frame the concept 'red' normally requires the presence of at least two reds, and so with the other colours. But such a mind could without difficulty notice the resemblance between the red, green, and blue patches which is connoted by the word 'colour', and could therefore frame that concept independently of the lower concepts.

The fact is that the pyramid arrangement of concepts is by no means logically essential. It is merely an arrangement which we choose because it is convenient for certain purposes which we need not discuss here. We could form the 'higher' concepts without first having framed the lower.

It may be true that to note the general resemblance between blue and green and red is more difficult, requires a more practised and alert mind than to notice the resemblance between red and red. The latter resemblance is more obvious than the former. But that is a psychological, not a logical, difficulty. It may also be true that as a matter of historical fact, men actually framed the lower concepts first, and then with the practice and skill thereby attained, went on to notice the more general and less obvious resemblances which give rise to the higher concepts. But all this is not to the point. The resemblance between red and green, though less obvious, is just as much given as the resemblance between red and red. And the general concept of 'colour' is therefore a concept of the given.

The same remarks obviously apply to such general concepts as 'sound', 'odour', 'taste', as distinguished from the concepts of particular kinds of sounds, odours, and tastes. Indeed the truth of what is here urged is perhaps more plain in regard to such presentations as those of taste than it is in the case of visual presentations. For it does not appear that the mind would experience any special difficulty in noting the general resemblance between differing tastes, and so forming the generic concept of 'taste', even before it had compared sweet with sweet or bitter with bitter to form the particular concepts of those special kinds of taste.

Even such a very general and pervasive concept as that of 'quality' is really a concept of the given, provided it is not taken in the sense of quality inhering in 'things'. In this latter sense it is a cognate of the concept of 'substance and accident', and belongs to a much later and more sophisticated stage of thought. It is not then a concept of the given. It is rather a metaphysical theory about things, or at least implies a background of such theory. But if, eschewing these advanced ideas, quality is taken in its simplest possible sense to mean only that general resemblance which colours, sounds, tastes, bear to one another, without any metaphysical implication of an underlying substance, it is then a concept of the given.

It makes no difference whether a concept of the given is formed from comparison of a sense-presentation with another sense-presentation, or with a memory-image, hallucination-image, or any other. The phenomena of memory no doubt present somewhat mysterious features. That, however, is not our present problem. From the point of view at which we now are the image which stands before, the mind in memory is simply part of the given. It exhibits all the features of givenness, and the distinction between memory-images and actual sense-presentations is not relevant to our present inquiry.

Concepts of the given elements of mental life are, of course, to be included among concepts of the given. Thus the concepts of 'concept', 'sensation', 'volition', 'emotion', are concepts of the given.

We have represented the concepts of the given as the earliest step in our knowledge. There are two possible misunderstandings to be avoided here. Firstly, it is not meant that the concepts of the given are necessarily first in historical or psychological order. It is meant that they are logically first. How knowledge began in the history of the race is a problem ………. that biological and anthropological inquiries may possibly throw some light upon the subject. ……………… Although we have urged that the psychological order of events frequently follows the logical order, it would be the height of absurdity to suppose that this is always the case. And where the two orders diverge, our business is with the logical only. We are here inquiring what knowledge would logically be possible to a self-enclosed mind which had not yet arrived at the knowledge either of 'things' or of other persons. Such knowledge, we must hold, is the logical beginning of all knowledge, since each of us must necessarily begin with his own self- enclosed experience. Looked at from this point of view it is clear that the logically first element of knowledge is the concepts of the given. They are presupposed by the later concepts of 'things', and more obviously by the still later forms of knowledge embodied in generalizations and scientific laws. One could not understand the mineralogical laws which govern the formation and distribution of rubies unless one had first the idea of what rubies are. And the knowledge of what 'ruby' means presupposes the recognition of the sense-qualities red, hard, and the like. And we shall find that whereas the concepts of the given imply nothing more than a simple act of comparison between two or more givens, e.g. between [two red patches, the concepts of 'things' on the other hand imply this and also a great deal of additional mental construction.

The second misunderstanding which we have to avoid goes hand in glove with the first. …….. What is here asserted is, firstly, that within any given psychologically normal state of knowledge, the element which we have called the concepts of the given can be logically, distinguished from the other ingredients. And secondly, that it is logically prior to any other kind of knowledge. A solitary mind, cut off from all communication with other minds, and living in its private world of phantasms, could not conceivably rise to the knowledge of external 'things'. It could know nothing of a common public world. But it could frame the concepts of the given. They are therefore the first steps which the solitary mind makes towards knowledge.

We need not concern ourselves overmuch with the formal question of what kind of judgement can be based on the concepts of the given. Knowledge, it may be urged, consists in judgements. This is not anything different from saying that it consists in concepts. For a concept can always be translated into a judgement, concept and judgement being but two forms or aspects of a single unitary mental activity. What kind of judgements, then, can the solitary mind, possessed of no concepts save those of the given, make? Bearing in mind that the question is not as regards psychological possibilities, I can see no reason why such judgements as 'This is red', 'This is loud', or even 'This colour is red', 'This sound is loud', should not be possible. If it be urged that 'this' is an impossible conception at this stage, since it implies a world of objects, I should dispute this view. 'This' merely signifies whatever occupies the focus of attention, and if taken in that sense is itself a concept of the given. Even the bare ejaculation 'Red!' is an implicit judgement the logical meaning of which is 'This is red'. Hence there seems no reason to doubt that the concepts of the given constitute genuine knowledge, however meagre.

We must now turn to the important question whether there is any evidence, in the rudimentary kind of knowledge which we are discussing, of its subordination to action; or of its validity being constituted by its practical usefulness. We may begin with a remark which is really of general application to all knowledge. The doctrine of evolution renders it probable that all knowledge, and therefore the elementary kind of knowledge involved in the concepts of the given, has been developed for practical reasons in the struggle for existence. No doubt intelligence grew because it was found to give its possessor an advantage over less intelligent competitors. No doubt knowledge would never have come into existence if it had not been for its practical value. And certainly these facts will have left their mark on the structure of knowledge. But it does not follow that knowledge is nothing but whatever belief happens to be practically helpful. Because knowledge of truth is useful, and has been evolved solely because it is useful, it does not follow that whatever is useful among our beliefs is true. To find out whether the pragmatic test is or is not the sole determinant of the validity of knowledge, we must examine the structure of knowledge at each of its several stages. And we will now proceed to do this for the first stage of knowledge, the concepts of the given.

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In studying the concepts of the given we are studying the original fountain and source of conceptual knowledge. We are at the very beginning. It is here, therefore, that we should begin our study of the relation of concept to action. Whatever we find at this stage is bound to have an important influence on the whole of our inquiry.

Wherever the relation of resemblance holds, even partially, between any two elements of the given, there is possible a concept of the given. A class can be based on any resemblance. And as any given element will stand in numerous relations of resemblance to numerous other elements, a single element may therefore be a member of many different classes. The red patch before my eyes is not only a member of the class 'red'. It not only resembles the neighbouring red patch, but it also resembles green in being a 'colour'. It even resembles a sound or odour in being a 'sensation'. In general, any given may fall into numbers of different classes. And since the number of different resemblances which may be observed to hold within the general field of the given will be indefinitely large, the number of possible concepts of the given is also indefinitely large.

It is here, if anywhere, as it seems to me, that the pragmatic factor will exert its influence. For the mind, confronted by the possibility of a very large number of concepts, and being unable to make use of them all, is compelled to select. What will be the motive of its selection? On what principle will it use some and neglect others? ….. For the ideal of pure knowledge has come into existence very late in the history of the race. Even now it is real only for a few men of science, scholars, and philosophers — a mere drop in the ocean of humanity. …… One is impelled to the conclusion that, as a matter of fact, selection must, throughout the greater part of the history of the race, have been made in the interests of action. The mind will have selected those concepts which are likely to be useful to it in the control of experience.

Consider, for example, the colour concepts. ………..
To the primitive man the resemblance between red and red, the concept 'red', is important. In the recognition of objects, the search for food, the flight from danger, colour will be in a thousand ways an important clue. But the subtle and tenuous resemblance between a colour and a sound which gives rise to the very abstract concept of 'quality', will be useless to him. It may, however, become very useful to those in a more advanced state of society whose interests necessitate the use of more abstract concepts.

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The recognition of an object by means of the application to it of a concept always involves, and in fact consists in, a prediction of possible future experience.

This predictive character of the concept is used by some writers as evidence of the complete subordination of knowledge to action, and of the truth of the general attitude of pragmatism. For it is pointed out that this predictive character is found wherever objects are conceptualized, and that it is in this way that the concept becomes a guide to action. I only know how to act if I can predict that if I do thus and thus, I shall experience such and such results. The concept enables me to do this. And this, and nothing else, is the function of the concept. The concept which successfully guides action is true. The concept which misleads action is false. Knowledge generally, therefore, is to be judged by whether it leads to successful action or not.

It cannot be doubted that concepts of objects have this predictive character, that they do guide action in this way, and that knowledge has in fact been developed in the struggle for existence as an instrument of practical action. But in suggesting that this predictive character is essential to a concept and is the sole ground on which its validity can be judged, the pragmatists appear to have overlooked the concepts of the given. For, unlike the concepts of objects, the concepts of the given do not possess this predictive character. The recognition of any object as what it is — an apple, a star, a philosopher — means that I read into the presentation a great deal more than is now actually presented. Into the presentation of the round red appearance I read the sweetness, the white interior, of the apple. But nothing of this kind occurs at the level of the concepts of the given. The concept 'red' implies nothing beyond the fact that the mind has noted the resemblance of this red to that red. The mind does not in such a case interpret. It does not predict, or add, or introduce anything from the outside. The concepts of the given are therefore, in themselves, useless as guides to action. Of course they become useful when they are taken up to form parts of concepts of objects. Thus in the recognition of an apple the concept 'red' becomes a sign of other possible experiences. But by itself the concept 'red' indicates nothing whatever beyond itself. This is the same with all the concepts of the given. In themselves they do not possess any predictive characters, and are not in any way guides to, action.

Perhaps the point is clear enough, but still I will put it in yet another way. To say of a certain visual appearance 'This is an apple' is to make various predictions of possible future experience which may guide action. But to say simply of the same appearance 'This is red' predicts nothing at all, and cannot in itself help action in any way. And yet it is true. Therefore its truth cannot reside in its utility.

In other words, the assertion that concepts are predictive is not universally true. It is only true of some concepts. Therefore this character cannot be the ground of the validity of conceptual thought in general. For no one will dare to assert that the concepts of the given are not perfectly valid concepts. They possess truth. And this truth they possess quite apart from any predictivity or utility, which they do not in themselves possess.

It will not avail to reply that in combination with other concepts the concepts of the given are useful. This we already know. No doubt the concept 'red' helps in the recognition of an 'apple', and the concept 'apple' of course is predictive and utilitarian. But the concepts of the given can logically exist without any knowledge of objects. It is knowledge of objects which is predictive. Therefore the concepts of the given can exist and be valid without any such connexion with concepts of objects as renders them useful.

This conclusion is profoundly significant. Not only does it show that perfectly valid concepts are possible whose validity cannot be identified with usefulness. But it is also clear that all later knowledge depends on such concepts, and that therefore, whatever influence practical activities may exert on the development of later knowledge, it is not the sole determinant. All knowledge, therefore, depends in the last resort upon a class of concepts which are valid apart from any pragmatic rest of validity. The fount and origin of knowledge, which is here in the concepts of the given, has a validity independent of any usefulness. This conclusion about the beginning must inevitably influence profoundly our further study of knowledge.

It will be clear, I think, that even here we have not over- looked the genuine insight which we admitted at the outset to be embodied in the pragmatic point of view. But among the concepts of the given utility does not constitute truth. It does no more than guide the mind's selection, from among innumerable concepts, of those most likely to be helpful to mankind. Concepts of the given are, in themselves, without any utility value. They acquire utility only as parts of concepts of 'things’. Their truth is independent of utility. But those which, when taken as parts of concepts of things, are useful, will be selected by the mind to form part of its everyday armoury of concepts.

It is evident that …we cannot … escape the conclusion that the initial position of every mind must be solipsistic. By this I do not mean that I shall remain in the belief that I alone exist. I think on the contrary that there is very good reason to believe in the existence of other minds. But in the meanwhile I assert that each of us must begin from within his own consciousness. Belief in other minds is not a datum.

That I am, to start with, only aware of my own thoughts and experiences, appears to be self-evident. Since it is the true beginning, it is clear that it cannot be an inference from anterior data, since in that case those anterior data would themselves constitute the beginning. We cannot prove the solipsist position in the sense of deducing it from some other position. But we can establish it by pointing out the given facts which constitute the position. This we have already to a large extent done, and nothing more is necessary here except once more to summarize those facts. They are as follows.

I cannot experience anything except my own experience. I can see my red, but I can never see yours. I can feel a pain in my leg. But I can never feel the pain in your leg. I can feel my emotion, but not yours. Even if your anger infects me, so that I feel it in sympathy with you, it is yet, in so far as I feel it, my anger, not yours. I can never be you, nor you me. I cannot see through your eyes, nor you through mine. Even if you can telepathically transfer a mental state, say an image, from your mind to mine, yet, when I become aware of it, it is then my image and not yours. Even if, as some think, I can directly perceive your mind, without having to infer it from your body, still this perception of your mind will then be to me my perception, my experience.

All knowledge, all philosophy, must be based upon experience. And from whose experience can I begin except from my own ? Whatever belief I hold on whatever subject must be either a datum of my consciousness or else an inference or mental construction which I base upon my data. If I accept a scientific belief on your authority, this belief must be an inference which I make from the sounds (words) I hear you utter, and from my belief in your repute as a scientific authority. Whatever I believe rests in the end upon the data of my own consciousness. Therefore all knowledge must have had its beginning in my own self-enclosed personal experience. This original solipsism is utterly unescapable except by prejudice or by refusing to see it. Philosophers blink the fact or gloss it over. But we shall begin here and loyally accept whatever results may follow.

……… the world of the solitary mind is not an unreal or imaginary world. It is the world which every one of us inhabits even now, though we have added many riches of existence to it.

In the concepts of the given the mind revealed the first activity of its thought. They were the first advance of the mind beyond the bare given. They were definitely thought, as distinguished from mere awareness or receptiveness. But these concepts could never lead the solitary mind out of itself, out of the grotto of its private phantasms, into the public world of external things. …………… To get from this stage to that of consciousness of the real external world will clearly require some quite new activity of the mind. And it must be our aim to discover that activity.

………… Our starting-point is the given, along with its special and elementary concepts. And the given means for each individual his own given. My given is not your given. Nor am I yet aware of your given or even of your existence. The existence of other minds is not itself part of the given. It is a later discovery. And therefore each mind must be, at its starting-point, completely solitary. It is aware of its colour patches, its sounds, scents, and tastes. These are its aboriginal world. They come and go like the images in a dream. It is unaware of anything else. It has no knowledge of the existence of any other mind. It has no knowledge of the existence of external objects in so far as these differ from mere presentations.

In what respects external objects differ from mere presentations is precisely the point upon which it is now desired to fix attention. For the world from which we start is a world of mere presentations. Yet we all of us come to believe in a world of external objects or 'things'. Before we attempt in the next chapter to ascertain how the mind reaches that belief, we had better first settle what the belief involves. How does a public external world of real objects differ from a world of mere presentations?

The distinguishing characters of such a world appear to be three. Objects such as tables and chairs and mountains differ from mere presentations in the following respects: (1) They have an independent existence. And by this use of the word independent I mean that they are believed to exist even when they are not presented to any consciousness. And (2) they are not private to my personal consciousness but are parts of a common world of knowledge which is shared by a multitude of minds. Finally (3) they exist for more than one of the senses. The same thing may be seen, touched, smelt, tasted, and heard. Mere presentations belong only to one sense. For example, the visual presentation, obviously, can only be seen.

The world of the original solitary mind differs from the world of 'things' in every one of these respects. (1) The solitary mind has no reason to think that its presentations go on existing after they have ceased to appear to itself. …………

The world of the solitary mind is (2) not public property. For the solitary mind is not even aware of the existence of other minds. …………….

Finally (3) the world of the solitary mind differs from the public world of objects in that it has not yet identified the objects of the different senses. I see the table and I also touch it. For the solitary mind at the beginning of its career the touch sensation and the sight sensation have nothing to do with one another, exist in wholly distinct universes. …………..

Thus, to recapitulate, the solitary mind is in the beginning confronted with its own given. It alone exists, solitary and solipsist in its world of presentations. This world of presentations is wavering, unsolid, and impermanent. The colour patches of which it largely consists come and go, flicker and fade. It is true that the mind has learnt to recognize similar presentations when they recur. It recognizes a red colour as red. It distinguishes it from other colours. It distinguishes colours from sounds. But in spite of this, nothing is permanent in its world. And above all it has no idea that anything goes on existing when it is not being perceived.

It is necessary to insist repeatedly upon this latter point. Let us imagine that what we know to be a green book is passed before the eyes of the solitary mind. To that mind this event will present itself simply as the appearance and disappearance of a green patch. When once it has gone out of sight the solitary mind has no reason whatever for supposing that it still continues in existence. …….. Even if the book is brought back into view a second time, this will be explained by the solitary mind as the appearance of another green patch similar to the first. It is not necessary, in order to explain the facts, to introduce the hypothesis of the identity of the two patches and their continued existence between appearances. This, as we shall see, becomes necessary as soon as a society of minds attempts to establish a common world. But it is quite unnecessary now when there is only one mind in the world. The view that nothing exists except what is actually being perceived and while it is being perceived, and that if what we should call the 'same' things reappear, this is due to the appearance of different but similar colour patches, is quite sufficient to explain all the facts in the world of the solitary mind. Hence it is evident that the solitary mind has no idea that anything exists unperceived by it.

This implies that for the solitary mind the esse of things which we afterwards regard as belonging to the external world is identical with their percipi, or if we prefer to translate this jargon into English, that their very existence is constituted by the fact of being perceived. …………..
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I will first endeavour to state in a brief form the preliminary conclusions which I shall reach in this chapter:
            (1) The solitary mind, or in other words the mind of every one of us when stripped of all the knowledge it has acquired, is confronted with a phantasmagoria of private presentations. It cannot be aware that these presentations continue to exist when it is not perceiving them. This knowledge is not a datum, and is impossible until the solitary mind gets into touch with other minds and begins in collaboration with them to construct a common or public world.
            (2) The solitary mind, further, cannot be aware of any distinction between the esse and the percipi of its presentations. It cannot, for example, draw any distinction between 'blue' and 'awareness of blue'. This distinction is not a datum, but a later construction.
            (3) The solitary mind cannot be aware of the existence of any permanent object beyond or behind the presentations. For example, when a penny is rotated in a certain way, it appears circular at one angle, then becomes more and more elliptical, and lastly appears as a narrow rectangular band. The solitary mind is aware of these various presentations or 'sensa', as they have been called, but not of the one unchanging 'real' penny which is supposed to lie behind them or in them. Such knowledge of permanent objects is not a datum but a later construction.
            (4) Later knowledge of all the points referred to in the last three paragraphs is a result of the construction of a common world by a society of minds. One of the first steps in this construction consists in inventing the fiction that a presentation can persist in existence when it is not being perceived. We shall see in the sequel why and how this assumption is made, and we shall see that it is no unusual procedure for the mind to invent fictions of this kind, but that it is of a piece with the whole procedure of knowledge and science. ………..
            (5) To the question whether the presentation is 'mental' or 'non-mental' we shall reply that this question is itself meaningless, and that the dispute which is supposed to centre round it is a mere quarrel over words.
            (6) It may be asked whether the presentation is dependent or independent on perception, I shall answer that the only sense in which a presentation can be independent of perception is when it exists unperceived. But an unperceived presentation, for example a green colour when no one is looking at it, is not a datum, and is unknown to the solitary mind. It is a later construction. In the pure presentation as such the esse is identical with the percipi. In this identity there is no room either for the relation of dependence or for that of independence.
            (7) It may be asked whether the presentation is dependent or independent on mind. The presentation is part of the passive not-I, and is therefore distinct from the mind, which consists in the activities of thought, attention, &c. Since they are not identical, relations of dependence or independence might possibly exist. But dependence may mean either causal dependence, or logical dependence, or the dependence of part on whole in the part- whole relation. There is no reason to regard presentations as caused by the mind, and their logical dependence can- not be satisfactorily established. And to ask whether the presentation is part of the mind would appear to have no meaning. It is identical with the question whether the presentation is 'mental', a question which has already been declared meaningless.

I would preface my detailed observations under these heads with the general remark that it is impossible to establish our position firmly until, in the next chapter, we have shown in detail how the mind constructs a public world. If we can show that, starting from a world in which there is no distinction between esse and percipi, the mind must necessarily construct a world in which that distinction exists, and if we can also show in what manner it is reasonable to suppose that this construction has occurred, this will render antecedently probable our present conclusions about the nature of the world before that construction takes place. Thus it is hoped that the conclusions of the present chapter and those of the next chapter will mutually reflect light upon one another.

Our first position is one which has already been explained, and is merely repeated here in order to give a complete list of our preliminary conclusions. The solitary mind has no reason to think that its presentations exist when they are not perceived by it. When the green book is passed before the eyes, and then taken away, the disappearance of the green patch will be for the solitary mind its ceasing to exist. Even when the green book is again placed before the eyes, the mind will have no reason to think that the green patch has continued in existence in the interval between its two appearances. The natural and obvious explanation of the facts will be that there have been two different green patches, alike no doubt in colour and shape, but none the less not identical, and that in the blank interval between the two appearances there had been no green patch in existence. The identification of the two appearances as the 'same', and the supposition, that the existence of this one thing was continuous between them, is a position which is certainly not self-evident, and cannot be a datum for the mind in its original contact with the world. It is a position which must have been in some way 'arrived at' after starting from the beginning. We shall find that, as it cannot be regarded as an inference from any datum, it must be considered a construction.

It is only when two or more minds meet and begin to compare notes that they will enter upon this construction together. The first glimpse of it begins to appear when we find that another mind continues to perceive the green patch after we ourselves have ceased to do so. How do we know that any object exists when we are not perceiving it? Surely the first step towards this knowledge is obviously taken when we make the discovery that some other mind was perceiving that object while we ourselves were not. The detailed steps of this development will be set out in the next chapter. But this much I have anticipated in order to make clearer the view here adopted that the solitary mind could have no reason to believe in the continued existence of its presentations after perception of them has ceased. It only begins to have reason for doing so when it attempts to establish, along with other minds, a public external world.

Any other view seems to me quite impossible. I, as a sophisticated mind, believe that the green patch goes on existing when I am not perceiving it. This belief must be either a datum, or an inference, or a mental construction. It is clearly not an inference, for there is nothing from which it could be validly inferred. From the existence of a green patch now (which I know because I see it) I cannot possibly infer the existence of the green patch yesterday or to-morrow. Such an argument would be a simple non sequitur, a fallacy into which no one could fall who clearly understood the steps, or rather lack of steps, of the argument.

My view, therefore, is that the belief is a construction. The only other possible alternative is that it is a datum. If it is asserted that this belief could be known to the solitary mind, i.e. to the mind before any construction takes place, this can only mean that the belief is a datum. It must be supposed that the mind in some way directly perceives that the presentation goes on existing when no one is perceiving it. This, however, is an absurdity. The green patch appears to me, and then disappears. At which moment is it that I perceive that it goes on existing after it has disappeared? Do I perceive this while it is still appearing to me? If so, this means that I now directly perceive the future, i.e. that I perceive what is not there to be perceived. Or do I perceive it after the green patch has disappeared? This means that while no green patch is appearing to me I yet perceive the existence of the green patch. Whichever alternative you choose will be equally absurd. The whole position that the belief which we are discussing is a datum is affected by a contradiction. For it implies that it is possible to perceive an existence which is by hypothesis unperceived.

We must conclude, then, that our belief in unperceived existence is not a datum, is not an inference, and must be a mental construction. It does not belong to the aboriginal state of the mind. It was not 'always there'. It has some- how been arrived at. It was unknown to the solitary mind.

Our second position is that for the solitary mind the esse of a presentation is its percipi, and that such a mind could not be aware of the distinction between esse and percipi ……… It means that even for us there is no distinction between 'blue' and 'awareness of blue', except such distinction as we ourselves have introduced by means of our mental constructions.

……… the solitary mind cannot know that its presentations con- tinue in existence when not perceived. For such a mind esse and percipi are simultaneous and coterminous. ……. There is no existence without being perceived and no being perceived without existence. Esse and percipi completely coincide, and why then should the mind distinguish between them?
It is different for us as sophisticated minds. For us esse and percipi do not coincide, since we believe that our presentations continue existing unperceived, and it is precisely because of this discrepancy that we are compelled to distinguish between the two. We have come to believe that things exist when no one is perceiving them. ………. But the solitary mind has no reason whatever to do so. When it says 'This green patch exists', it can mean nothing except 'This green patch is being perceived by me'. The two expressions will have for it no difference of meaning.
……………… …………….. ………………
…….. When I look at the green patch, what do I perceive about it? I can perceive that it is green, that it has a certain shape, possibly that it moves or changes in some other way. These are characters which I actually see. But apart from these can I see its existence? Can I perceive an existence which is distinct from its greenness, its motion, its shape, its other visible qualities? Such an existence is a pure abstraction. It may be for some purposes a legitimate abstraction. But as an abstraction it cannot be perceptible to the senses, it cannot be given.

A number of arguments have been urged against the view here adopted. It has been widely asserted that in the experience of 'awareness of green' we distinguish between the awareness and the green. The awareness is an activity of our minds. It is 'mental'. The green is not.

It is quite true that we do make this distinction between our awareness and that of which we are aware. But in my view this distinction is itself the result of the mental construction of the external world. Because the belief that there is an external world independent of mind, and that this external world is composed of independent objects which are green, hard, spatial, and so on, is ingrained in us, has become part of our very blood, we think of green as something distinct from our awareness of it. I do not assert that to think this is erroneous. On the contrary I shall assert that it is true. But this is because truth itself is largely composed of mental constructions. The view that the distinction which we are discussing is a mental construction does not imply that it is false. But if it is asserted that the distinction exists apart from mental construction, that it is primordial and essential to consciousness as such, then this assertion is false. For it is equivalent to the view that the distinction is given. And we have seen that it cannot be given.

If we can in imagination withdraw ourselves back into the world of the solitary mind ….. we shall see that in such a world no distinction between green and awareness of green could ever have arisen. It has evidently arisen as a result of the belief that green goes on existing when I do not perceive it. Because I believe that the green tree is there when no one is looking at it, I am compelled to think that the green tree is not the same as my awareness of it. But I came to believe that it goes on existing when I am not aware of it as a result of a train of thinking the details of which will be explained in the next chapter. One of the first steps in this train of thinking is the discovery that other minds are seeing the tree when I am not. Because you see it while I am asleep I am forced to the view that it exists when I do not perceive it. This is one of the first steps in the building up of the construction of an independent existence. This construct is therefore dependent upon my awareness of the existence of other minds. But the solitary mind in its private world is not aware of the existence of other minds. And therefore it cannot be aware of the independence of its objects, or of the distinction between green and awareness of green which that independence implies. In other words the distinction is not intrinsic to the presentation as such.

Realist writers on this point seem to put the cart before the horse. They think that the independence or 'non- mental' character (whatever that may mean) of the object can be deduced from the existence of the distinction between green and the awareness of green. The truth is that this distinction is made as a result of the mental construction of the independence of the object. We first construct that independence, and then argue 'Because green is to be regarded as existing apart from, and therefore independently of, my awareness, therefore the green and the awareness must be thought of as distinct from one an- other'. Consequently it is illicit thereafter to deduce the independence of the object from the existence of the distinction, a proceeding which is nevertheless a hot favourite among realists.

Those who think that the distinction is not constructed, but primordial or given, may urge in favour of their view that the awareness is an activity of the mind, whereas the green of which we are aware is a pure passivity. I think the former of these two statements is mistaken. Pure awareness is not an activity. The mind, when it is active, does something to the object. For example, the acts of abstraction and conception — genuine mental acts these — alter the object by cutting away a part of it and considering only the other part. The act of comparison between two objects involves distinguishing between them while at the same time linking them together. The act of attention selects. But pure awareness as such appears to me to be wholly lacking in activity. It is purely passive. That is why, if you stare blankly at one object for a long time, eschewing thought, and avoiding the activity involved in shifting the attention backwards and forwards from one point to another, you will rapidly become unconscious. Pure awareness, without any of the characteristic activities of mind added to it, is equivalent to unawareness, unconsciousness. …… For the essence of mind, the essence of the 'mental', is activity.

The impression that awareness is an activity which can therefore be distinguished from that of which the mind is aware is probably the result of confusing attention with awareness. (To this confusion I attribute the famous assertion of the realists that the distinction between green and awareness of green is intrinsic and primordial.) In all ordinary sense perception we select our object and concentrate attention on it. Hence awareness is always accompanied by attention. If the attention wholly ceased it is probable that the mind would lapse into unconsciousness at once. Attention is a mental activity.

No doubt it follows from the position which I am here adopting that awareness is not a part of mind at all, but is in some way 'non-mental', which will no doubt appear at first as a curious result. Nevertheless I accept it, except that I am of opinion that the adjective 'non-mental' is misleading and inappropriate. As has already been pointed out, the mind distinguishes between itself as active in attention, conception, abstraction, inference, and thought generally, and on the other side the pure passivity of the presentation. This is the only real basis for any distinction between the I and the not-I, the 'mental' and the 'non-mental'. Now if we say that the awareness of the presentation is the presentation, that there is no intrinsic distinction between green and awareness of green, then of course it follows that the awareness (which is only another word for the presentation itself) is part of the not-I, is 'non-mental'.

Thus our point of view agrees with realism to this extent, that it abolishes any intermediatory 'idea' between the mind and its object. The mind, for us as for the realists, sees its object, or rather sees its presentation, direct. It stands face to face with it. And this is a profoundly important point of contact.

No doubt it appears strange to speak of an awareness as if it were not part of the mind at all, but rather of the external world. But the reader has perhaps by now forgotten that it is not we who speak thus, but rather the solitary mind. For us, sophisticated as we are, there is a distinction between awareness and that of which we arc aware. And when, as a result of our mental construction of an independent external world, we have made that distinction, we then begin to regard that of which we are aware, the presentation, as belonging to the independent world, and the awareness as belonging to us, to our consciousness. That has become our natural point of view. And bearing in mind that, since 'truth' includes not only the aboriginal given but also all that has been added on to it by means of legitimate mental constructions, it will be seen that it is the 'true' point of view. And it is therefore natural that when we penetrate back into the dim pre- history of the mind, when we speak from the point of view of the solitary mind as we are now doing, there should result turns of expression, modes of viewing things, which are apt to strike us now, as sophisticated minds, with a kind of shock owing to their essential strangeness. It is thus that we experience a sense of strangeness when we hear that for the solitary mind awareness is not a part of consciousness, but of the not-I.

That the distinction between the awareness and the presentation itself is not made by the solitary mind, is not aboriginal, but is dependent on the discovery of other minds and the subsequent construction of a public world, is borne out by a circumstance to which attention has been pointedly drawn by those very writers who differ from our view. It has been pointed out that in the case of visual presentations we very easily make the distinction between the awareness and that of which we are aware; but that in the case of bodily sensations such as headache we do not make this distinction. …….. For the world of sight is a public world, the world of headaches and other bodily sensations a private world. You and I believe that we both see the same green object. But we never suppose that we feel the same identical headache. Hence the world of sight comes to be regarded as an independent world which, because you are aware of it even when I am not, does not depend for its existence on my being aware of it. Therefore in the case of sight we distinguish green from our awareness of green. We are compelled to do so by the fact that the green which is supposed to exist when I am not aware of it must clearly be different from my awareness. This distinction then extends itself from the green of which I am not aware to the green of which I am aware. Here too I begin to suppose that there must be a distinction between the green and the awareness of the green. So in the visual world the distinction becomes universally established and taken for granted. But in the world of bodily sensations no such necessity is felt, and no such distinction established, be- cause I never suppose that you feel the same headache as I do, much less that you feel it when I am not aware of it. Thus the difference between the visual world and the world of headaches in this respect is exactly what we should expect if, as our theory holds, the distinction between a presentation and our awareness of it is not intrinsic or primordial, but is a product of our construction of a public world.

It is also argued that we have a 'primitive faith’, an 'instinctive belief’, in the existence of an independent external world, and therefore in the reality of the distinction between esse and percipi. This is also sometimes called an 'animal faith'. In some form or other, explicit or tacit, it seems to be relied on by most realists. And necessarily so. They are compelled to rely on some such weak shift. For they have to admit that the existence of an independent external world cannot be proved, i.e. that it is not a valid inference from our presentations.
The various appearances of the penny as I rotate it are the only existences of which we have direct evidence. That these appearances go on existing after we cease to perceive them, or that they existed before we began to perceive them, can never be proved. That there exists behind the varying appearances a single unchanging ‘real’ penny can also never be proved.
…….. The obvious conclusion is that these beliefs are mental constructions. But as this would destroy the preconceived notions of realism, it is alleged instead that we know of the existence of the independent world by means of a 'primitive belief or by 'faith'. Thus Dr. Broad says: 'The belief that our sensa are appearances of something more permanent and complex than themselves seems to be primitive, and to arise inevitably in us with the arising of the sensa. It is not reached by inference, and could not logically be justified by inference.'

Such an attitude is contrary to the rationalism, the determination to follow whither reason leads us to the end, to take philosophy seriously, which we in this book have adopted as our ideal. Philosophy cannot, in my opinion, accept as gospel the deliverances of primitive instinctive belief any more than it can accept the mysterious un- mediated revelations of the mystic. And a 'primitive instinctive belief’ is, I venture to assert, no more than a euphemism for an obstinate prejudice. We believe that there is an independent world. Granted. Is this true, and why? 'Because we have a primitive belief in it', say these philosophers. But this is only saying over again that we believe it, which we knew before. We believe it because we believe it. This is a poor position for a philosopher to take up!

By a 'primitive belief is meant, I presume, simply a belief which people have held for a very long time. It may have been accepted by our semi-human ancestors of a million years ago. It may have so ingrained itself into our race that a tendency to believe it has become hereditary, and has only to be awakened in each new individual by the faintest suggestions from his fellows. For it is by no means certain that we have not 'innate ideas' at least to the extent that we have inherited through hundreds of thousands of years certain tendencies of thought and feeling. Even though our belief in an independent world is of this kind, it does not follow that we ought to accept that fact as its sufficient justification. We might be compelled to accept on nearly similar grounds as a 'primitive belief the view that the earth is a flat disk.

Not, of course, that we dispute the truth of the belief in an independent external world. Nor do we dispute that, as a matter of psychological fact, that belief may have be- come in the course of long ages practically instinctive. But it is utterly absurd to give this as the logical origin of the belief, or as its justification. Our point of view would appear more reasonable and philosophical. It is that as the belief in question admittedly cannot be an inference from our direct experience, it must be a mental construction. It is 'true', because, as will be proved later, truth includes mental constructions. To explain it as a 'primitive belief’ is merely to give it the status of an unaccountable prejudice. I am prepared to give it a better justification than that, and to exhibit it as part of a rational scheme of knowledge founded on mental constructions which are legitimate because governed by rational laws. This point of view has, of course, to be developed and justified in the rest of this book.

The assertion that our belief in an independent world 'arises inevitably in us with the arising of the sensa' seems to be quite unjustified. ……….
The assertion that the belief 'arises in us with the arising of the sensa' must mean, if it means anything, that the independence of the object is given, that it is directly perceived by the senses. But we have already seen clearly that this is false.
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…………. For the solitary mind the awareness is not mental, for no awareness of green exists apart from the green itself. The awareness is only distinguished from the green, set up as an entity on its own account, and classed as 'mental' after, and as a result of, the construction of a public external world. Before that construction has been made, the awareness is not a mental state. It is identical with the presentation, which is itself not a mental state, but a part of the not-I. …………. After the construction has been made, on the other hand, the distinction between the awareness and that of which it is aware comes into being.

Our third and fourth positions are that the solitary mind cannot be aware of the existence of any permanent object beyond or behind the presentations, and that our belief in such objects, as also our belief in the existence of unperceived presentations and in the distinction between esse and percipi, are later mental constructions. These views have been fairly well explicated in the course of our discussion already, and it is unnecessary to say much more here. They cannot, of course, be fully established until we have shown in the next chapter how these mental constructions come to be made. But in the meanwhile we may recapitulate their essential foundations briefly as follows. It is clear that what the mind is immediately aware of is the presentations or sensa, and nothing else. It cannot perceive the supposed permanent 'real' objects which these are believed to represent. Nor can it perceive presentations existing unperceived. This is the absolute foundation of our position. The next step consists in the realization that from these immediately perceived data no logical inference of any kind can be drawn as to the existence of unperceived presentations or 'real' objects. I think this is admitted by all competent philosophers of all schools. Nor can one even suggest what kind of inference could possibly be put forward as fulfilling the necessary conditions. Therefore unless one is prepared to rely on a mysterious 'primitive belief’ or 'animal faith' one is compelled to conclude that our beliefs on these subjects must have been constructed by the mind itself. Reliance on 'primitive beliefs' is totally irrational and incomprehensible, and is a mere 'chucking up the sponge' on the part of philosophy. Hence we must explore the path which seems to be opened up by the suggestion that our beliefs on these matters are mental constructions.

Our fifth position concerns the question whether presentations are 'mental' or not. The adjective seems to me wholly inappropriate, and it is my conviction that those who discuss the question are not themselves clear as to what they mean by the word mental. For what can be meant by either asserting or denying that a green patch is mental?

There are apparently two possible meanings which might be attached to such language. Firstly, we have seen that the mind distinguishes its own activities from what it passively suffers, and that the activities constitute the I, the passivities the not-I. This distinction, which is made even by the solitary mind, is the only true distinction between 'mental' and 'non-mental', and in this sense it is quite clear that the green colour or other presentation is non-mental. And this is, I believe, the only intelligible sense in which the question can be asked and answered.

But this does not appear to be quite what is meant by those who agitate the problem. If they urge that the presentation is mental they appear to mean that it has that quality which causes the images of dream, hallucination, or delirium, to be regarded as mental or 'subjective'. And in distinguishing the mental from the non-mental they apparently have at the back of their minds the difference between dreams and veridical perception. A dream is a series of private presentations. The world of veridical perception is a world of common or shared presentations. The dream is popularly supposed to be in some way a 'mental' phenomenon, whereas the real world is regarded as 'non- mental'.

Now the essential differences between the presentations of dream and of veridical perception are that the former are private and in some ways lawless, while the latter are shared in common by many minds and are subject to the general laws of physics. In other words the differences are extrinsic to the presentations themselves. They consist in the relations of the presentations to each other and to other things outside themselves. There are no intrinsic differences. The dream-images cannot be discriminated because of their paler or less vivid appearance. We only know them as dreams when we cannot fit them into the common world shared by us and by other conscious beings. It follows that when people speak of dreams as in some special way mental they must be referring to their character as private. It does not appear to be their character as lawless which is important here. For that is very much less obvious to the plain man than is their private nature. And one is led to the conclusion that 'mental', when applied to dreams and other non-veridical perceptions, really means nothing more than private, as distinguished from shared.
If mental means nothing beyond private then of course the presentations of the solitary mind are mental. But for my part I protest that this language is misleading and erroneous, and that the doctrine of the 'mental' character of our presentations is meaningless.

The mistake begins when we call dreams mental. Since there is no intrinsic difference between dream- images and those of veridical perception, therefore both are mental or else neither are. But this is not realized. The habit of calling dreams mental has sprung up because it is falsely supposed by the unphilosophical that there is some intrinsic difference between dreams and veridical perception. The presentations of veridical perception are (quite rightly) classed as 'real' or as belonging to the physical world. Those of dream are classed (quite rightly) as 'unreal' and as excluded from the physical world. The unreal then becomes confused with the totally different conception of 'error'. And as error is undoubtedly in some way peculiar to mind, and produced by mind, the unreal entities of the dream are then classed as mental. This seems to be something like the psychological history of the erroneous usage by which dreams are classed as mental while veridical percepts are classed as non-mental, whereas it is clear that in respect of being mental or otherwise they both stand on exactly the same footing.

The popular error then gets transferred from vulgar thought into philosophy. Since dreams are supposed to be mental, and since their essential distinctive character is really their privacy, hence the same word 'mental' gets attached to any presentation which is private, and therefore to the pure presentation as such, or, as we have called it, the presentation of the solitary mind. The presentations of every mind at the beginning, before that mind enters upon, and takes its part in, the public world, must be private. And therefore, according to the erroneous usage which we are reviewing, they must be mental. And since all presentations, even those of veridical perception, are ultimately, when isolated and taken out of their context in the public world, private to each individual, therefore all presentations may come to be represented as mental.

This confusion has, of course, been powerfully helped along by Berkeley's misuse of the word 'idea'. This word, for him, covered presentations. The word as properly understood refers to thoughts or activities of the ego of some kind. Hence if you call a presentation an idea, you tacitly imply that it is of the nature of thought, of the nature of the I, and so mental. This is of course the very opposite of the truth, since the presentation is essentially passive and belongs to the not-I. And it is probable enough that Berkeley was himself misled into this confusion by that same popular error as to the difference between dreams and veridical perception which we have just discussed.

Thus the discussion whether presentations are mental or non-mental, as this discussion is usually conducted, is simply meaningless. I see a green patch. I say that it is green, that it is circular, that it is increasing in size, that it is moving from left to right. All these terms mean something. But now if you inquire whether the green patch is mental, what do your words mean? When you are pressed as to what you mean, you will have to say one of two things. Either you mean by calling it mental that it belongs to the activities of the I, and not to the passivities of the not-I, in which case what you are saying is manifestly untrue. Or you mean that it is private as distinguished from common or public, in which case you are merely using the word 'mental' in a stupidly erroneous sense.

It is equally meaningless to inquire whether the green patch is 'inside the mind' or 'outside' it. One can see that an object which exists unperceived might be metaphorically described as outside the mind. This is no more than a metaphor, but is unobjectionable as such. But to discuss whether the pure presentation as such, when it is being perceived, is inside or outside the mind, seems to me, so far as I can judge, the same as discussing whether it is mental or non-mental. The discussion takes for granted a distinction in kind between the presentations of veridical perception and those of dream, and supposes that the former may be outside the mind and non-mental, while the latter are inside it and mental. The one thing that is clear, however, is that the two stand on precisely the same footing. If the green patch which I see in veridical perception is outside my mind, then so is the green patch of my dream. If the green patch of my dream is inside my mind, then so is the green patch of veridical perception. The whole discussion rests on the false distinction between the supposed mental character of dreams and hallucinations and the supposed extra-mental character of veridical perception. When once it is seen that this distinction is illusory, that the difference between dreams and 'real' presentations is extrinsic, consisting in their relations with their contexts, and not intrinsic, then it must also be seen that the whole discussion is meaningless.

Our last two (6th and 7th) positions refer to the question of 'independence', and may be quite shortly expounded. The esse of the pure presentation is neither dependent nor independent on its percipi. The relations of dependence and independence involve the presence of two distinct terms to be related. But the esse and the percipi of the green patch as it exists for the solitary mind are not two things, but one. They are identical. Automobiles are not dependent on motor-cars. Nor is Jack dependent on John. Where there is identity, there is no room for relations of dependence or independence.

But this cannot be said of the relation between esse and mind or knowledge generally. My mind consists in my thoughts and mental activities. It is the I. The presentation is part of the not-I, and is clearly not identical with the I. And it may therefore be asked whether the presentation is dependent, or independent, on mind. This question may have several meanings.

The questioner may be referring to causal dependence. If so, the plain answer to the question is that there is no ground whatever for asserting that presentations are caused by minds. The causes of a presentation seem to be always previous presentations, or at least the causes seem always to fall within the not-I. The cause of the sound of thunder is not my mind, but is the lightning. Neither my will nor my thinking has anything to do with it so far as can be seen. I cannot by willing cause a green patch to appear or to disappear. Nor will any act of thinking, inferring, conceiving, or abstracting influence the matter.

Some philosophers have asserted that the world of the not-I is in some way a logical consequent of mind. But mind is in that case usually thought of in a transcendental sense, as referring to a universal or cosmic mind. Discussions of such transcendental questions lie quite outside the scope and the spirit of our inquiries here. But I may hazard the remark — and it seems fair to say — that the logical dependence of presentations on mind has never been satisfactorily established.

Dependence may also mean the dependence of part on whole. To assert that presentations are dependent on minds in this sense would mean apparently that they are parts of minds. The application in a literal sense of the part-whole relation to minds seems inappropriate. But, if it is not taken in its literal sense, it seems to me that the assertion that a green patch is part of my mind can only be another way of alleging that it is 'mental'. And this view has already been discussed.

Hence I do not see any relevant sense in which it can be said that presentations are dependent on minds.

I shall only use the concept of independence in one reference. I shall call the public external world of objects 'independent' …. For that world is conceived as having existed before my mind, or any particular minds, came into existence, and in general as existing whether any minds are aware of it or not. This character I shall call its independence. That this independence on mind is itself a construction of mind is, of course, of the essence of our philosophy. But that need not deter us from the use of the word independence in the reference explained.

Finally, it has to be understood that esse and percipi, even when for the sophisticated mind they are not identical, are always correlative. It will be a part of our thesis that no existence can be conceived except in terms of actual or possible perception. The esse of the presentation while it is being perceived i s its percipi. The esse of the office table in the dark night when no one is aware of it, though it is not perceived, yet has to be thought of as if it were perceived. If the reader is pleased to call this invariable correlation between existence and perception a dependence of one on the other I have no objection. It is a matter of words only. Personally, though I shall speak of the independent external world in the sense explained in the last paragraph, I shall not otherwise use the concepts of dependence and independence, having, in fact, no use for them.

Firstly, we must remind ourselves of a point which has already been made. The mental development which we are about to witness is primarily a logical development, but must nevertheless, according to our view, stand in some real relation to the actual history of mind. Our primary question will be, how can the solitary mind, shut up within its world of private phantasms, come to a knowledge of the solid permanent external world? How can it logically pass to that end? What is the logical justification of its belief? There never can be any logical passage, if by logical passage we mean inference. There is no evidence whatever to convince the solitary mind of the existence of the public world. Not only is there no demonstrative proof, but there is not even the faintest trace of probable reasoning. We shall conclude that the belief is a construction of the mind itself. And our main business will be to exhibit the logical order of the steps of this construction.

But it is also our view that the construction must actually have taken place in history, and indeed that it must take place anew in each individual mind. As to the first point, we surmise that somewhere in the history of life on the planet there must have been a time when the rudimentary minds of living organisms did not realize the existence of an external world, and that belief in it must have slowly evolved. Will it be asserted that the Cambrian trilobite possessed it? Or even that the present-day lobster does so? Must not the world of the trilobite have been some- thing like that which we have described as the world of the solitary mind, only even more rudimentary in being less clearly realized than the picture we have drawn of it? Can it be supposed that rudimentary forms of animal life realize that the green patch which represents a tree to them to-day is the same as yesterday's green patch, and has gone on existing between whiles? Can we be sure that even the intelligent dog which is our companion can distinguish its dreams (i.e. its private world) from public reality? Be it far from me to dogmatize about obscure and perhaps insoluble problems of animal psychology. Yet it seems implausible to suppose that belief in an independent first breathings of life. And if it did not, it must have been evolved. (Will those, by the way, who think that this belief is a 'primitive belief tell us whether it descended suddenly, like a bolt from the blue, upon humanity, or if not, how, when, and why, it evolved?)

Thus belief in an external world must have had a beginning in the dim past. It must have had stages of development. There is, of course, no direct evidence of these stages. Unfortunately we have, except in a metaphorical sense, no fossil minds. We have to reconstruct the development. Why should the stages not have been the logical steps which, as we are about to show, would naturally lead the mind to that end?
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We must hold, moreover, not only that the human mind has in the past implicitly gone through the stages of the mental construction which we are about to set forth, but that each present-day individual must do so somehow in his infancy. Has the mind of the three-days-old child any recognition of the independence and externality of the world? Does it know that the light which it sees is the same light as other minds see, that it is public, that it was there before it was seen and will be there after? Even to debate these questions seriously would be absurd. How then does each of us come by these beliefs?

……….. Must it not be believed that in growing up each of us learns to use his vision? We have to learn to interpret the sensations which we receive through our eyes, and to recognize objects. It is well known that this process involves subtle and elaborate inferences, and these clearly must be carried on implicitly and unconsciously in very early childhood. It is no more unlikely that the infant implicitly goes through the process of constructing the external world than that it goes through the elaborate intellectual processes involved in the interpretation of visual stimuli. Both processes alike are no doubt enormously helped out by heredity and the facility gained thereby.

Our second prefatory remark is that the account which will be given of the construction of the external world does not profess to be anything more than diagrammatic. To give a precise and detailed account of the intellectual processes involved in vision would probably prove a task surpassing the subtlety of the human mind. And it is the same here. It will only be possible for us to mark out the essential, the most important, considerations which have led the mind to the construction of the independent world. I think we can still trace out the main steps of the ascent, but no more. Moreover these steps must necessarily be set out here in serial order, whereas it may be that the mind actually makes them either in a different order or possibly takes several steps simultaneously. We can do no more than pick out the main points in the progress and exhibit them in the order which seems to be the most logical.

Let us emphasize once more the nature of the starting- point. ….. It is my given from which I must start; … it is the private given of the solitary mind. That mind is not aware of the existence of other minds, since the existence of other minds is not given. Much less, then, can it be aware of the givens of other minds, or of a common given, or of any kind of public world.

Before the solitary mind there passes, as in a dream, a shifting, unsolid, phantasmagoria of colours, sounds, smells, and other sense-data. It ebbs and flows. It changes continually like a kaleidoscope. When a sense-datum repeats itself, the mind can note the resemblance and apply its concepts of the given. It recognizes red, and distinguishes it from green. It also distinguishes its own acts of thinking, conceiving, comparing, attending, from the passivity of its sense-data, and can rise thereby to the distinction between the I and the not-I. It does not call this not-I either 'inside' or 'outside' the mind, either 'mental' or 'non-mental', either 'dependent' or 'independent' on itself, either 'real' or 'unreal'. All such distinctions lie in the future, and are the result of the construction of the external world which we are about to study.

Let us suppose that a green book is placed before the eyes, is removed for a short while, and is then placed before the eyes again. The solitary mind perceives this, not of course as a book, but as a series of appearing and disappearing flat green patches. On its second appearance it notes the resemblance of green to green, and applies its concept of the given, 'green'. But it has no reason for actually identifying the first green patch with the second. It will suppose that a green patch came into existence and then ceased to exist, and that after a while another green patch came into existence. And it will suppose that both green patches ceased to exist as soon as they respectively disappeared from its own vision.

Beyond this stage the solitary mind can never get. It is essential to realize that, unless at this stage of development there come upon the scene the phenomena of communication with other minds, consciousness will remain at the low level just depicted for ever. The solitary mind can never by its own unaided efforts come to believe that what it senses persists when it is not being sensed. The concept of the external world is a social product, and could not have existed but for communication with other minds. Without such communication any further progress of knowledge is absolutely blocked.

It would seem then that our next step should be to explain how we become aware of other minds. And that would really be the most logical procedure. But it will be more convenient to avoid interrupting the course of our argument at this point by a discussion on that topic, and to leave it over to be dealt with in a later chapter. For the rest of this chapter I shall therefore assume that the solitary mind has somehow (in a manner to be later explained) become aware of the existence of other selves, and has got into communication with them.

The justification of this procedure is simple convenience. In reality our knowledge of an external world and of other selves are interdependent, and must have grown up together pari passu. But we have to follow each interwoven thread separately. It does not much matter in which order we take them. But I think it will render the under- standing of our argument easier if we do not break off here to consider the source of our knowledge of other minds. Assuming, then, that the solitary mind has now got into communication with other minds, we will proceed to trace out its further development in a series of mental constructions.

First Construction: That the presentations of one mind bear to the corresponding presentations of other minds the relation of resemblance.

Suppose that a green book is placed before two minds A and B. They both see a green patch at once, and they are able by means of words, or signs of any kind, to communicate and compare notes of their experiences. The first construction set out above means that the green patch of A resembles the green patch of B in the same way as two green patches in the same mind may resemble each other and give rise to the concept of the given 'green'. It is ordinarily assumed, when two or more minds are surveying the same scene, that they all see, hear, and smell similar colours, sounds, and odours. When you and I look at a tree we assume that the tree which you see is like the tree which I see, and so on.

It will be carefully noted that it is not stated in this construction that the minds A and B see the same green patch, but only that they see two similar green patches. That these two green patches are numerically identical is a later idea which requires for its establishment a separate construction.

Now the fact that a common world has in fact been established, and that we are all able to talk to each other as ifour several presentations resemble each other, does not prove that they in fact do so. All it proves is that between the series of presentations of one mind and that of another there is a correspondence of order or relation. ……………. Provided the order and relations of the two series of presentations agree in two minds, they will be able to communicate with one another, to discuss and compare experiences, and to build up a common world. That they do so, therefore, does not prove that the content of the presentations which they receive resemble each other in any way whatever.

Nor is there any other way of proving this fact. How can I possibly know that my red resembles your red, or that any sensation of mine resembles any sensation of yours? Obviously there is only one way in which it could be proved, and that would be by comparing our sensations, e.g. my red with your red. But who is to perform this act of comparison? I can never see your red and you can never see mine. And a third party who might be impartial can see neither. It is clearly the same with all our experiences. I cannot feel the pain in your leg, and whether what you call pain is in any way similar to what I call pain I have no means of knowing. There is therefore no possibility of proving the similarity of our presentations. It is not an inference which follows from any of the data with which we started. Not only is it not demonstrable. It is not even a probable conclusion. It is not an inference of any kind.

I have no positive assurance that my red is not your blue, or that what is colour to me does not make on your mind an impression similar to my impression of sound. I have no positive assurance even that our two sets of presentations are in any way commensurable……. Even if this is so, it would not be a bar to communication and to the establishment between us of a common world, so long as our presentations, though dissimilar in content, correspond in order and relations.

One way of interpreting these facts would be to argue that as the resemblance of the presentations of different minds is irrelevant to the establishment of a common world, ……. But this would be a mistake for two reasons.

In the first place, although it may be possible to conceive the common world without including the idea of the resemblance with which we are dealing, yet this is not the ordinary conception. It would be a highly unusual and sophisticated conception which would not occur to any one except a philosopher. Now we are not at present trying to exhibit the construction of philosophical ideas. …..We are attempting to exhibit the construction, which has gone on perhaps for millions of years, of the ordinary human being's naive realism, his belief in an independent world which goes on existing when he is not aware of it, and which exists for other people besides himself. And this naive realism certainly does include the conception that the presentations of different minds resemble one another. The plain man takes it for granted that, when he sees a green object, another mind looking at the same object will receive a precisely similar green presentation.

There is, moreover, a second reason why this first construction cannot be left out. Our second construction, it will be found, carries the mind a step farther. It will assert, not merely that the two presentations which A and B receive when they look together at the green book are similar, but that they are numerically identical. Now they cannot be identical if they are dissimilar. If we are later to identify them, we cannot now admit that they do not even resemble each other. And from this point of view it will be seen that our first construction is a necessary part of the general process of constructing an independent public world.
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We may proceed, then, with our construction. It is impossible to produce one tittle of evidence to show that your red resembles my red, or that in general the presentations of one mind resemble the presentations of any other mind. And yet the mind believes it to be true, and builds this belief into its conception of the public world. Since it is not given, and is not an inference from anything which is given, it must be a mental construction. And this means that the mind has simply assumed its truth, has invented it as a fiction which suits its purposes.

…… Why does the mind make this assumption? ……

What reason, then, has the mind to take this step? The reason seems fairly obvious. As far as the evidence goes, the mind has before it two alternative beliefs, either of which it may adopt. When minds A and B are looking at the green book they may believe either (1) that their two presentations are similar, or (2) that they are dissimilar and even incommensurable. Neither of these beliefs has any evidence "whatever either for or against it. The mind is entirely free to adopt whichever it pleases. Which will it adopt, and why? Will it not naturally adopt the simpler? And is it not clear that if the society of minds adopts the view that every mind has its own peculiar presentations unlike those of every other mind, this will lead to an enormously complicated universe? A perfectly unnecessary complication. To adopt the belief that the presentations of different minds resemble each other will be a great simplification of our picture of the universe. This view is chosen, then, because it is a simplification, and for no other reason.

This is our first example of what we shall later call alternative truths. A free choice between two equally unprovable assumptions frequently presents itself to the mind. We shall hold that in such cases both of the rival assumptions are equally 'true'. They are alternative truths. They are alternative paths each of which would have been equally legitimate for knowledge to have taken. But that one has actually been built into the fabric of human knowledge which presents the advantage of greater simplicity and economy of thought. Many examples will come before us. One of these may be mentioned briefly now, though its full significance must be left to be expounded on a later page. The choice between Euclidean and non-Euclidean geometries is on precisely the same footing as the choice between the beliefs that the corresponding presentations of different minds resemble each other, and that they do not resemble each other. But the mind has for most ordinary purposes chosen Euclidean geometry solely because for those purposes it is simpler. And when, as in relativity mechanics, non-Euclidean geometry is chosen, that choice also has been made purely because, for the particular purposes in view, that geometry is simpler. So it is here. And I have mentioned the example of geometry here in order to sow thus early in the reader's mind the seeds of the following thought. The principles which govern the mind's procedure in the most advanced science will be found even here too in the lowest and humblest kind of knowledge, viz. that which we receive through our senses in the perception of the ordinary objects of the external world. Knowledge is of a piece all through, and shows everywhere the same characters and processes. Just as the geometer may choose any geometry he pleases, so the mind might have chosen the path indicated by the assumption that the presentations of different minds bear no resemblance to each other. We might all have believed that. But knowledge has actually chosen the other path for the reason given.

It will repay us to consider at this point what meaning can be attached to the fiction which the mind has constructed for itself, and in what form of proposition that meaning will naturally express itself to the mind at the level of development which we have now reached. More precisely, what can it mean to assert that my red resembles your red? I understand at once what is meant by- asserting that two reds, both of which are within my own experience, are similar. I compare them by looking from one to the other, and I then find this resemblance given. And to say that any two things are similar seems to depend for its meaning on the possibility of their being compared. But where any comparison between two things is impossible and inconceivable, has it any meaning to say that they are similar?

My red and your red exist in different universes which are absolutely cut off from one another. The consciousness of each of us is a separate world. Not only is a comparison of our experiences in fact impossible, but it is difficult even to find any self-consistent meaning which can be attached to the idea of such a comparison. It is not merely a physical impossibility for me to see your red. If that were all, the difficulty might conceivably be some day overcome by the advance of psychological science. But the difficulty is a logical one. If I could see your red, your red would have become mine and, in so far as I saw it, ceased to be yours, and therefore the conditions of the comparison would have vanished. Or to put it in another way. Suppose that I could annihilate the barriers of personality and get into your mind and see your red. Yet it is still I who see it. And how do I know then that the red which I see is the same as the red which you see? I cannot know this so long as I remain I. In order to know it I must cease to be I and become you. But if my personality and yours are thus fused into one, then there are no longer two experiences to compare, and no relation of resemblance can be asserted.

The difficulty of finding an intelligible meaning for our first construction is thus very great. And such a meaning cannot be found so long as we attempt to express it in the form of a categorical judgement. So far, the solitary mind has made only categorical judgements. It has asserted 'This is red', 'This red is like (or unlike) that red', 'Red is different from green', and so on. But as soon as the mind enters upon its career of mental constructions a new form of judgement becomes necessary to express its new in- sights. It has to invent the hypothetical judgement. Let us see how this is.

To say that any two things, even when they are both within my own experience, are similar, implies either that a comparison has been made or at least that it might be, and that if it were made the alleged resemblance would be seen, 'A is like B’ means either ‘A and B have been compared and found alike', or it means 'If we compared A and B we should find them alike'. An assertion of similarity is necessarily relative to a possible act of comparison. Hence 'My red is like your red' means 'If we could compare our reds we should find them similar'.

The condition, as we have seen, is actually an impossibility. We could not conceivably compare our reds. But the mind does not boggle at this difficulty. It swallows it because it suits its purposes to do so, because unless it does so, it will never be able to build up a common world and a society of minds. We shall find that this is a characteristic, not only of this particular mental construction, but of all those mental constructions which have the character of creating or positing new existences.

We may bring this truth into relation with our previous conclusions by expressing it in another way. To the mind at its present stage, it must be remembered, the esse of the given is identical with its percipi. An esse apart from a percipi will be, up to date, inconceivable to it. Now resemblance is one of the concepts of the given, or in other words the resemblance of presentations to one another is, for the solitary mind, a perceived relation. Its esse will, of course, therefore be its percipi. But what has now been asserted by the mind, in this its first construction, is the existence of a relation of resemblance which is not, and cannot be, perceived. I see that the two red patches now opposite my eyes are alike. This is a direct act of perception. But if I affirm that my red patch resembles your red patch, this is to assert the existence of a resemblance which no mind in the universe can ever perceive. This assertion of an unperceived existence, even though it be of a relation and not of a presentation, is implied by our first construction, and is already a transcendence of our old point of view that esse and percipi are identical.

But how will the mind conceive this new esse which is not percipi? ……… And this means that its new esse, though not expressed in terms of an actual percipi, will be expressed in terms of a possible one. So that now and hereafter when the mind affirms that anything exists unperceived, what it affirms is that 'If . . then such an existence would be perceived'.

This, of course, will be disputed by those who still cling to the preconceptions and prejudices of realism. They will assert that the affirmation of an unperceived existence is categorical, not hypothetical. And if the reasonings which I have adduced in the last chapter have not prevailed against those preconceptions, I am not aware that I can do anything further to prove my point. The essentials of our contention may, however, be shortly recapitulated. The initial state of the mind is necessarily solipsistic. The solipsistic or, as we have called it, the solitary mind has no reason whatever to believe in an unperceived existence. Until it gets into communication with other minds, it has no reason to think that its red patch exists when it is un- perceived by itself, nor, of course, that any resemblance exists unperceived between its own presentation and that of another mind. Its esse is therefore identical with its percipi. Even when it gets into touch with other minds, it still never perceives an unperceived existence, nor can it ever infer such an existence from anything which it does perceive. But there are reasons, namely the necessity of developing its systematic communication with other minds, which force it to invent such an existence. This existence^ e.g. the relation of resemblance which we are now considering, is not something that is factual or 'actually there'. It is merely supposed or hypothetical, and can be expressed only in the hypothetical form 'If. . then it would be perceived'. This follows inevitably from the position that belief in an unperceived existence is a construction. For a construction is a supposal. Hence the only way in which our view that all existence is relative to an actual or possible perception can be escaped is by showing that unperceived existence is not a construction. And the only way of showing that would be to show that it is either an actual perception or an inference from an actual perception. That an unperceived existence could be perceived is an absurdity. And that it could be inferred from anything that is perceived will be admitted by every competent philosopher to be impossible. Hence our view seems the only feasible one.

In making the assumption of the similarity of the presentations of different minds, the primitive mind is performing a new kind of operation, something quite different from mere awareness of the given, from the concepts of the given, or from any possible inference therefrom. This new operation consists essentially in extending the given in imagination into a region in which nothing is given. It consists in imagining a given where there is none. It is essentially an act of imagination. I see two red patches within my own experience and I note the resemblance between them. This resemblance is itself something given. Taking this experience of a given resemblance as a model, the mind now imagines a similar experience where in fact no such experience either is or could be, namely between the presentations of two different minds.

The belief in the similarity of the experiences of different minds is the first of a long series of assumptions which the mind makes on its way to knowledge, the first of its mental constructions. And we shall find that the characters of this mental construction frequently repeat themselves. These characters are as follows:
(1) The belief which is constructed is such that it can never be either proved or disproved, nor can there ever be any the slightest evidence for or against it. It is pure assumption.
(2) The assumption cannot be given a categorical meaning. It has to be expressed in the form of a hypothetical proposition. If a categorical proposition is used to express it, such a proposition is merely elliptical.
(3) The antecedent clause of the hypothetical proposition expresses an impossible condition, that is, a condition which could not actually exist, but is only a supposal.
(4) The whole mental construction is a work of the imagination which supposes its experience extended into the void where there is in fact no experience. The construction is used to fill up gaps and voids in the given.
(5) The mind creates nothing new. Imagination uses always materials already supplied by the given.

Second Construction.: That the corresponding presentations of different minds are identical, and that there are not many universes, but only one.

Nothing, perhaps would appear so self-evident to the ordinary unphilosophic man as that there is but one universe, and that when he and his friend sit at the dinner table there is before them a single common table, not a separate table for each mind. And yet a little reflection reveals that it is rather the opposite principle which is really self-evident, namely that there exist as many universes as there exist minds. Your red presentation is not my red presentation. We have seen that there is no evidence that they even resemble one another. Much less, then, are they identical. When we both look at what we afterwards regard as one object, say a green book, a green patch is present to your mind, and another green patch is present to mine. There are two, not one. And when a thousand minds are observing the book, there will then exist a thousand green patches. Each mind has its own world which is separate and absolutely cut off from all others.

Now suppose that the minds A and B observe together the same series of events, say the appearance of the green book, its being opened at a white page, its being closed again, and finally its being replaced by a red book. The series of presentations then is (neglecting questions of size, shape, &c.) green, white, green, red. A and B compare notes, and they find that two precisely similar series of experiences have been presented to them. Whatever has happened in A's world has had an exact counterpart in B's world. There are still, of course, two separate worlds. But they run parallel courses, so that whatever happens in one happens in the other also.

A and B are like two people sitting in two cinema houses watching two cinema shows. ….. they find that the films are similar. ……….but also divergencies.
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............. A and B, are primitive minds each of whom has only just made the discovery that another mind exists. What they seize upon, both as striking in itself and as useful to them, is the agreement which they find to exist between their two worlds. This agreement forms the foundation stone of their future common world. Mere differences would lead them no- where. If all the worlds of the various minds in existence were wholly different, with no features of agreement, why, then that would be an end of the matter; no common world could be built up; each mind would remain for ever in its private world. Hence it is the agreements on which A and B fasten as significant to them, ignoring the differences for the present.

A and B have discovered, by the first construction, the similarity, but not the identity, of their two worlds. But there are in truth not merely two minds in existence and in communication with one another. There are multitudes, A, B, C, D, . . . N, And thus A and B and the other minds come to believe in the existence of multitudes of universes all alike and all running the same course.

But the multitudes of minds confronted by similar universes will inevitably come to talk, and later to think, as if there were only one. For this will present itself as an obvious labour-saving device, a simplification of thought and a convenience of conversation. ……….. To think of them all in terms of one universe, or as if there were only one, will be simpler and easier and will serve all purposes. So the belief in a single world becomes established, and the older view that there are many universes is forgotten. Like an organ which performs no function, it decays. The belief in one universe comes in the course of time to appear self-evident.

We have here, once more, an example of the principle of alternative truths. The mind is free to make its choice between belief in many universes or one. Both these beliefs would be 'true'. But one is simpler and more convenient for most of the mind's purposes than the other. And the simpler belief is chosen and embodied into the structure of human knowledge. But if there ever arises any purpose for which it is more desirable to adopt the hypothesis of a multiplicity of universes, that hypothesis will be adopted.

The importance, appearing thus early in the history of knowledge, of the principles of simplification and economy of thought may appear to some to warrant a pragmatist theory of knowledge. It is too early as yet in the course of our inquiry to decide this issue. But I will, by way of anticipation, indicate the lines upon which I propose to proceed. The pragmatist would presumably hold that if two alternative hypotheses equally suit the facts, and if one is chosen solely because it is the simpler and more useful, that one alone is true and its rival false. This makes simplicity and utility constitutive of the truth. But I shall hold that the two alternatives are both equally true, though it may be that only one has been adopted into the system of human knowledge. The nature of truth is not deter- mined by practical considerations, such considerations determining only which of two or more rival truths shall be selected for the practical or theoretical purposes we happen to have in view.

……… the principle which is now adopted in justification of the second construction is that facts or complexities of fact which can make no conceivable differences in the mind's outlook or in the accomplishment of its practical or theoretical purposes may be ignored and treated as if they were not facts. When you and I look together at a green book, it may be a fact that there are two green presentations. But it will make no difference to anything in the universe (except perhaps to our epistemology, and for that we can make special provision as has been done here) if we talk and think as if there were only one common green patch. To do so will be much simpler and will facilitate the establishment of a common world and a society of minds. Facts which have no conceivable bearing on any- thing are for the purposes of knowledge not facts.

(Also) We do not here suppose that something exists which is not and cannot be perceived. ………. In the present case we adopt a precisely opposite principle. We suppose that something which is perceived does not exist. The construction can therefore be expressed in the categorical form 'There is only one universe'.

Nor is there, of course, any question of the extension by the imagination of something given into a void in which in fact nothing is given. That too characterizes only those constructions which suppose something to exist which cannot be perceived.

Nevertheless the second construction is a true construction. For it is a belief which the mind does not find in experience or the given, and does not infer from anything that is experienced. It is a pure assumption.

Finally we must not omit to note the close resemblance which knowledge bears even here in its most rudimentary forms to the forms which we find in the most advanced science. What is called the hypothetical character (or, as I prefer to call it, the constructional character) of scientific knowledge is now well recognized among men of science themselves. Here is a quotation from a recent writer taken almost at random. 'Whether the man of science regards his atoms as having an ultimate reality or not, does not affect the validity of the theory ; the theory is just as useful in introducing order and promoting discovery if they are merely polite fictions as if they are desperate realities'. This writer has not envisaged the one further step which has to be taken if we are to make this idea fruitful in epistemology, namely to recognize that 'polite fictions' may enter into the constitution of reality, and form part of 'truth’.

Third Construction: That the presentations of a mind may continue in existence unperceived by that mind, provided that some other mind perceives them.

The second construction was founded upon the agreement which minds found to exist between their separate private worlds. But it was noted in passing that between the various worlds there is not only a general background of agreement, but also a number of specific differences. And it was noted that these differences would in due course have to be reckoned with. The third construction is based upon such a difference, and is an attempt to meet the difficulties which that difference places in the way of a mind which seeks to carry out consistently the view that there is only one universe.
………… ……….. …………….
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………… A and B were looking at the green patch. It disappeared from one of their universes, but not from the other. It remained continuously present to B's mind even during the interval when A was not seeing it. By the second construction the two universes are one, and it is supposed to be the same green patch which both have been observing. If this view is to be retained, there is only one conclusion which A can come to. He will be compelled to think 'Since the green patch which appeared to B is identical with the one which appeared to me, and since it went on existing in B's mind after it had disappeared from mine, it follows that my green patch went on existing in B's mind when it was absent from mine'. And the general conclusion will be drawn that presentations of one mind may continue to exist unperceived by that mind so long as they are perceived by some other mind. This is the third construction.
………… ……….. …………….
… the main construction with which we are here concerned is the new belief that a presentation may go on existing unperceived by the mind to which it originally appeared so long as some mind is perceiving it. This will at first sight seem very revolutionary and subversive of ….. previous views. …… For up till now the fundamental truth of A’ s and B’ s universe was that the esse of presentations is their percipi. This was settled doctrine. It was pristine self-evident truth. It was a dogma which would have lasted for ever if only A and B had continued to regard their universes as separate. But now, because they have come to think of them as one, they are compelled to admit this new and revolutionary construction.

They will not, of course, admit as yet that a presentation may exist unperceived by any mind at all. They have had no reason to go so far as that. That will come later. But for the present the mind, while admitting that its presentations may continue unperceived by it, will still insist that they must be perceived by some other mind. Esse is still in that way percipi, although that doctrine has received rather a strange twist.

………… But either A and B must swallow this paradox, or they must give up their common world. They cannot have it both ways. Faced with this dilemma they decide to swallow the paradox. They will not give up their common world. The convenience which it introduces into thought and action is too great to be sacrificed. And it is not unreasonable to suppose also that, having found companionship with each other, they fear the sense of loneliness and isolation which would result from their going back to their separate self-enclosed universes. So they accept the view that presentations go on existing when one is not aware of them so long as they exist in some one else's mind.

The first two constructions were adopted by the mind because they simplified its view of the world. The third construction is not made directly for this reason, but because it is forced upon the mind by the previous two. Having accepted the belief that there is only one universe, the mind cannot without self-contradiction hold out against the opinion that my green patch goes on existing in your mind even when I am not aware of it. Thus whereas the motive of the first two constructions was economy and simplicity, the motive of this third construction is consistency. This is frequently illustrated in the history of the development of knowledge. Having accepted one construction we are then compelled to create another in order to avoid a breach of the laws of logic. It is in this way that inference and logic in general perform their chief function in the world of thought, i.e. by ensuring that our various mental constructions do not contradict one another. This is also true in the history of science.

The logical characteristics of the third construction may now be noted. In the first place it is obvious that it cannot be proved. It is a pure assumption.
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The third construction …. is a true construction in that the content of that judgement is neither perceived nor inferred, but is invented by the mind.

Fourth Construction: That presentations may exist when no mind is aware of them.

The next stage in the mind's creation of an external world is obviously that A should come to believe, not merely that his presentations may continue to exist un- perceived by him, so long as B perceives them, but that they may continue to exist when no one at all perceives them. The human mine! has now come to believe (I am speaking, not of philosophers, but of the naive realism of the unreflecting) that green patches and the like exist in the world unperceived by any mind whatever. But there is a gap here which cannot be bridged by any evidence. How do I know that the desk in my office continued existing when I left it behind to-day and went out for a walk? I know it because during that period another member of my family stayed in the room and saw it there. This is precisely the case which is provided for by the third construction by which I believe that my presentation of the desk goes on existing in the mind of another person even when it is absent from my mind. But how do I know that the desk continued in existence when no one was in any way aware of it? The answer is that there cannot possibly, in the nature of things, be any evidence of this. There is evidence that things go on existing so long as some one perceives them, provided we assume that different people perceive the same things. But when no one is perceiving a thing, it is clear that no one can give evidence of its existence, and that there cannot be any such evidence. There is not, never has been, and never will be an iota of evidence that the universe or anything in it goes on existing when no mind perceives it or that it existed before there were any minds to perceive it. The belief must therefore be, according to our view, a mental construction.

What other view are we to take of it? That it is a 'primitive belief ? But that is merely to call it a prejudice. 'Belief in the existence of things outside my own biography', says Mr. Russell, 'must from the standpoint of theoretical logic be regarded as a prejudice, not as a well- grounded theory.' When an eminent realist writer says this of his own views, what need have we of further witness?

And yet we must hold that we can do knowledge a better service than calling its foundations prejudices as realists do. We can show that they are mental constructions, and that mental constructions are 'well-grounded theories', having their own logical structure and justification, which we shall study in due course.
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Taking it for granted without further argument, then, that belief in the existence of unperceived presentations is a construction, our next step must be, as in the cases of the previous constructions, to inquire why the mind creates this construction, and what leads it to do so. The general purport of the answer is clear. This construction is but a continuation of the mind's previous tendencies to simplification and economy of thought. ……………
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…………. the third construction) is only a half-way house, and that it must finish what it has begun. It has established with other minds a common world. It has abolished the multitude of universes in favour of one. This introduces a beautiful simplicity into its thought, which would otherwise be uselessly complicated, and it also renders society, the easy communication of mind with mind, possible. But this new simplicity and uniformity are incomplete. They depend on every one keeping awake and alert to see that things in the universe don't get lost and go out of existence. This is clearly unsatisfactory. It would be much better if the universe would go on of itself without some one having perpetually to watch it. From every point of view, there- fore, the mind is impelled to adopt this fourth construction and 'to believe that the universe exists when no one is perceiving it. With this construction the independence of the external world is assured, though still further constructions are necessary before the ordinary naive view of the world is complete. But we have before us already an independent external world, in that it is now existent whether any one is aware of it or not, and independently of any mind. Thus by a gradual and somewhat adventurous process, by means of dangerous and daring speculations, the self-enclosed solitary mind, for whom nothing existed except the fleeting phantasms of its own private world, has created for these phantasms an objectivity outside that world, thrust them forth into a strange, cold, mindless wilderness of an outer world, given them permanence and solidity, decreed that they shall have existed before mind itself was born and shall continue to exist after mind is dead. In this way that solid, permanent, everlasting universe was created by our minds.

The logical characteristics of the fourth construction are the same as those of the first. For, like the firstconstruction, it creates in imagination a new existence, namely presentations during periods of time when no mind is aware of them, or, as we might say, unpresented presentations. These logical characters are the following:
(1) It is entirely unprovable, a pure assumption.
(2) It cannot be expressed in a categorical judgement, but only in a hypothetical judgement of which the antecedent clause is an impossible condition. For what categorical meaning can be attached to a statement that anything exists unperceived ? We must remember that, for the solitary mind, esse is percipi. Even when the mind ceases to be solitary and has built up its common world, its conception of existence will not involve a complete break with the past. It must still think of existence as relative to perception. Existence is what is, or at least might be, perceived. Having regard to the fact that esse is originally percipi, the categorical assertion of an existence wholly out of relation to perception is equivalent to the assertion of an existence which does not exist. And this contradiction can only be avoided by the hypothetical form. To assert that anything exists unperceived can only mean that if the circumstances were suitable it would be perceived; it can only accurately be expressed in the form ‘If . . . , it would be perceived’.

That the table exists when no one is aware of it means 'If some one were looking in the right direction, he would see the table’. That there exists a side of the moon which is turned away from the earth, and invisible to us, means that if one could travel out in space to beyond the moon, and if one could take up a suitable position for purposes of observation, one would see that side of the moon. That atoms exist means that if one could magnify sufficiently one would see atoms. This, of course, involves the view that it must be possible to imagine some kind of a model of anything which can reasonably be asserted to exist in the atomic world, a view which physicists are at the moment inclined to dispute. I shall discuss the issue in a later chapter. For the present I will only reiterate that it appears to me impossible to conceive any existence in a manner which does not involve the thought that in suitable circumstances that existence might be perceived. To assert that anything exists surely means that it can be perceived if one is in the proper position to perceive it.

(3) The 'if' clause in all these cases represents an impossible condition. It differs from such a proposition as 'If I look at the table, I shall see it'. This proposition refers to the future and it is possible that the condition may be carried out, i.e. I may look at the table in the future. And the future existence of the table, when I am looking at it, will be a perceived fact. But 'the table is now existing unperceived' means 'if some one were now looking at the table, he would see it'. But by hypothesis no one is now looking at the table, and therefore it is impossible that the condition 'if some one were now looking' should be fulfilled. Some one looking in the future will not be some one looking now, and no amount of looking in the future will ever satisfy the condition 'if some one were looking now'. Similarly if we suppose the physically impossible, namely that we shall some day have instruments of magnification sufficient to see atoms, that will show that atoms exist then, i.e. when they are seen. It cannot prove that they exist now. ………….. The impossibility of the condition to which we are here referring is ………. the logical impossibility of thinking at the same time both that.we are looking and that we are not looking.

(4) The mental construction is a work of the imagination which extends actual experience into the void where no experience in fact exists. We merely imagine the green patch which we now see extended into the periods of time which are void of it in the sense that no one is perceiving the green patch during those periods.

(5) Clearly the mind creates nothing new. It uses the materials already supplied by sense. The table which we do not see is supposed to be exactly like the table which we do see. It is coloured, hard, square, &c. As we are so often reminded, atoms used to be thought of as being like tiny billiard balls. And even now, if we are right, they will have in the end to be thought of as in some way following sensuous patterns. But that is a disputed question which we must leave over to another chapter.

Fifth Construction: That there exist 'things’ or 'objects' , which are not identical with presentations; and that the presentations are 'qualities’ of the 'things’; and that the 'qualities’ may change while the 'things’ remain the same.

When a scientific theory is put forward, its function is to explain, or reduce to law and order, a set of facts. If it satisfactorily explains all the relevant facts known in connexion with the particular subject of the theory, it may be taken as a working hypothesis. If, later on, new facts become known which appear inconsistent with the theory, it must either be abandoned as false, or it must be modified in such a way as to bring it into conformity with the new facts.
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In the fifth construction, which we are about to examine, we have an example, precisely similar to those which are scattered broadcast throughout the fields of science, of a theory being modified to meet new facts which are inconsistent with it in its original form.

The primitive minds which met in communication with one another first noted the fact that their separate private worlds ran parallel to one another. We compared them to persons in separate rooms watching duplications of the same cinema film. This parallel character of the many private worlds was seized upon as a basis for the identification of the private worlds with one another, and their reduction to a single public world.

But there also appeared differences between the many private worlds. One kind of difference appeared when it was discovered that a presentation which existed both in your world and mine, and the two appearances of which we accordingly identified as one presentation, might persist in your world after it had vanished from mine. This discovery led to important modifications of the theory of the common world. It led to the belief that the common world is independent", that presentations can exist un- perceived.

And now another set of differences forces itself upon the notice of the primitive minds and threatens once more to destroy their theory of the common world. It is discovered that when a number of minds are simultaneously looking at what they have decided to regard as the 'same' presentation, the private appearances to them of this presentation are in fact not exactly similar. There are slight differences which, in the enthusiasm of their discovery of the common world, had escaped notice. Suppose that they are all looking at the 'same' brown patch (which is what we afterwards come to describe as a penny). The sameness of its character as a brown patch to them all is what had first struck them. A more accurate comparison of notes reveals that it appears as a circle to A, as an ellipse to B, as a narrower ellipse to C, and as a thin band or rectangle to D. It is further discovered that to A it is so large that it occupies nearly the whole field of his vision, while to B it is much smaller, and to C and D it is so small as to appear a mere speck. (This we afterwards learn to explain by the fact that the various spectators are at varying distances from it. But that is a later story. What we have to concentrate on at the moment is the mere fact of difference.) Differences make their appearance not only in the visual world, but also in the worlds of touch, smell, taste, and hearing. The 'same' sound is very loud to A, but scarcely audible to B, And so on.

Now these facts are in flat contradiction to the theory of a common world which all the minds have accepted. For how can the 'same' brown patch be at the same time circular, elliptical in various degrees, and rectangular? How can it be several different sizes at once? How can the 'same' sound be both very loud and almost inaudible? A brown patch cannot be several inconsistent shapes at one and the same time. Contradictory characters cannot co-exist in the same presentations. And it looks therefore as if the whole theory of a common world will have to be abandoned unless it can be so modified as to meet the new facts. Can it be?

There is only one way in which it can be done. The same entity cannot be both the same and different. We must have one entity to bear the differences and another the identity. And this is the solution which the mind adopts. It invents the concept of the 'thing' which is supposed to support, or lie behind, the presentations. The presentations vary. They are different for each person. The 'thing' itself remains self-identical and without contradiction. The presentations become 'appearances' of the 'thing'. The circular, elliptical, and rectangular brown patches are regarded as so many appearances of one single 'object', the penny. This, as it seems, saves a nasty situation. The new conception is applied everywhere universally. The world is no longer made up of presentations, but is full of objects.

The conception is full of difficulties, but these are concealed from the primitive mind by the extreme vagueness with which it is held. What is the nature of the 'thing' which underlies the presentations of brownness, shininess, circularity, &c.? There is no reason for supposing it circular since some of its presentations are elliptical, nor elliptical since some of its presentations are circular. Moreover since circularity, ellipticity, and other shapes, are presentations, can any of them characterize what is by hypothesis different from any presentation? Can we attach any intelligible character to the 'thing' at all? More- over, what is the relation of the 'thing' to the presentation? It is all very well to call the latter sometimes an 'aspect', sometimes an 'appearance', sometimes a 'quality'. But what do these words mean? What is an aspect, what an appearance, what a quality? And how are these conceptions related to the conception of the 'thing'?

These and many other difficulties there are, and the hopeless attempt to clarify and solve them has constituted no small part of the occupation in all ages of those philosophers who have failed to recognize that the conceptions which they are thus trying to make consistent do not represent real facts in the world at all, are not in their nature consistent and clear, but are no more than the makeshift devices of the primitive mind in its efforts to build up a common world. They are no more than essentially vague 'points of view' which that mind invented and adopted for its own ends.

But we are not here concerned with philosophers and their conceptions. We are concerned only with the primitive mind. And that mind cannot be expected to philosophize or think clearly. It holds the conception vaguely and confusedly without sense of its inherent difficulties. Or even if there are difficulties which are apparent to it, it will swallow them rather than adopt the only other alternative which is open to it, namely to give up its hardly found and newly cherished common world. For these reasons too our reconstruction of the concept cannot be too precise. It cannot rise to exact definitions, which are not only foreign to the primitive mind but impossible to supply in the nature of the case to a makeshift ‘point of view'. We cannot say precisely how the presentation is to be conceived as related to the 'thing'. We cannot give a single clear answer to this question. Sometimes the presentation is conceived as an aspect, sometimes as an appearance, sometimes as a quality. Perhaps the view of it as a quality is the most characteristic of the primitive mind and the most generally employed. And for that reason only we have treated this construction as the construction of the 'thing' and its 'qualities'.

Just as the ether of space was invented without evidence of its existence because it was required to bear the undulations of light, so the 'object' is invented without evidence of its existence because it is required to bear the character of identity amid the changes among presentations.

As soon as this fifth construction has been created, it soon begins to appear that the theory of the 'object' possesses another advantage besides that which originally recommended it. The primary reason which led to its adoption was that when different minds were viewing simultaneously what they had decided to regard as the 'same' presentation, there were nevertheless differences between the appearances of it to different minds. Now not only is the same presentation thus different to different minds viewing it at the same time, but it is also different to the same mind viewing it at different times. The colour patches as we watch them change their colour, their shape, and their position. We watch a red patch turn gradually orange and then yellow. We watch a brown patch change before our eyes from circular to elliptical.

These changes seem to raise difficulties for the subsidiary construction by which it was decided to adopt the view that the successive momentary existences of a presentation are identical with one another and constitute 'one' presentation. There is no difficulty in this so long as the continuing presentation does not change its character. If the circular green patch remains circular and of the same shade of green, and does not move from its place, it is easy to regard its successive existences as existences of the 'same' presentation. But suppose the circular green patch gradually changes its colour, shape, and position. What warrant have we for regarding the whole series as 'one' presentation? If it is red and circular one instant, yellow and square the next instant, it obviously involves a contradiction to call the series the 'same' presentation. For how can a presentation, the essence of which is to be red, be the same as one the essence of which is to be yellow? And how can a square presentation be the same as a circular one?

The new concept of the 'thing' and its qualities has the advantage that it offers a ready solution of these difficulties. For now we can say that the 'thing' remains the same, while its qualities, which are the presentations, change. The leaf turns from green in the summer to yellow in the autumn. In spite of the change of colour we regard it as the 'same' leaf all through. But we could not do this if we had not invented the concept of 'thing' or 'object'. If presentations alone existed, then the green patch (which is the leaf in summer) is clearly not the same presentation as the yellow patch (which is the leaf in autumn). There would be two different leaves, not one. But by means of the concept of the 'thing’ we circumvent this. It is true, we say, that the colour has changed. But the colour is not the thing itself. The colour is only a quality of the thing. Hence though the colour has changed, the thing itself has remained the same. Thus arises in general the important conception that a thing may remain the same and self -identical while all its qualities change. This is a construction which is convenient and simplifies our view of the world.

We will consider, lastly, the logical characters of the fifth construction.

(1) It possesses the essential character of all true mental constructions in that it cannot be proved true, is not derived from experience, but is simply invented by the mind to fill up a place in the mind's scheme of knowledge. It is obvious, in the first place, that the thing which lies behind the presentation cannot be sensed or directly experienced in any way. For if it could, it would itself be a presentation. Neither can it be inferred from the existence of presentations. Obviously any inference which would seek to pass from the perceptible world of presentations to an unseen and unknown world behind it must needs be a fallacy. It is idle to argue, for example, that presentations must have a cause outside themselves, and that this cause will be the 'thing'. For causation is a relation between things which we find in experience. In other words, it is a relation among presentations. When we say that a — b constitutes a causal series we mean that, granted the given conditions, this series is invariable in our actual perceptual experience. Experience warrants us in asserting that the causal relation subsists between our presentations among themselves. But this can give us not the slightest right to say that causes must exist behind presentations in a world which is never experienced at all.

It is clear, then, that the conception of the 'thing' is not inferred from anything which we experience, but is simply created by the mind as a fiction which gets it out of the logical difficulties into which it has fallen as a result of its belief in a common world. The object of the fiction is to give plausibility to the theory of the common world and to get rid of the contradictions which beset that theory when it is seen that it involves identifying a round with an elliptical coloured patch, or, in general terms, that it involves regarding mutually contradictory things as the 'same'.

(2) Constructions which assert the existence of anything take the hypothetical form. For such constructed existence is, of course, unperceived. And the mind's assertion therefore amounts to 'If ... , we could perceive it’. Logically, this must also characterize the present construction. To affirm that an unperceived 'thing' exists behind our presentations can only mean, if we press it, that if we could get behind our presentations we should perceive it. It is true that such an idea is absurd and full of contradictions. If we could perceive the thing behind the presentations it would then itself become a presentation. It would therefore presumably require another 'thing' behind it. And this will lead to an infinite series. Moreover the conception of the possibility of perceiving things apart from their qualities is manifestly absurd, since the qualities of a thing are that by which alone it is possible to perceive it.

But, as already remarked, the whole conception of the 'thing' and its qualities leads to numerous logical difficulties, which have been a standing puzzle to philosophers who insisted on taking it seriously, but are lightly glossed over by the primitive mind which invented this make- shift idea. Nor need we trouble ourselves about this new contradiction. It is in the same boat with the old. The naive mind holds the conception so vaguely that these difficulties simply do not appear to it. There are two different and inconsistent ways of looking at the matter. The primitive mind attempts to hold to both these ways, choosing whichever alternative happens to suit it at the moment. For we may, firstly, say that the thing is quite separate from its qualities, lying as it does behind them and supporting them. We adopt this point of view when we wish to explain how the same object can have contradictory qualities, e.g. how the penny can be both circular and elliptical at the same time. In order to explain this it is necessary to emphasize that the thing itself is something different from its presentations, so that it remains unaffected by the contradictory characters of the presentations. The difficulty about this point of view is that it leaves the thing itself absolutely without character and unknowable. It is a pure blank which we can never hope to reach, see, or understand. When this is pointed out, the primitive mind will veer round and adopt the following attitude. It will say that the presentations are the qualities of the thing itself, and that in knowing those qualities we are knowing the thing. The leaf is green, and soft, and shaped in such and such a way. When we know these characters, we know the leaf itself, for they are the characters of the leaf. When this point of view is adopted the difficulty which then arises is that it is no longer possible to explain the contradictory characters of things. For the separation between the thing and its presentations has been practically abolished, with the result that it is no longer possible to blame the presentations for the differences while preserving intact the sameness of the thing itself. If when we see the penny as circular we are getting knowledge of the real thing, the penny itself, then our neighbour who sees the penny as an ellipse must also be getting knowledge of it. It must therefore be both circular and elliptical at one and the sametime. And this is precisely the contradiction which the whole idea of the 'thing' was supposed to avoid. Thus the primitive mind veers between these two contradictory points of view, adopting whichever is convenient at the moment, or confusing the two, and in any case failing to see the pitfalls and contradictions into which it is falling. This, I believe, is a fair description of the attitude of the average unreflecting man of to-day or of any period.

The logic of the matter cannot be pressed any further. The conception which the mind has invented to enable it to preserve its common world intact contains these contradictions immanent within itself. It is at bottom an inherently self-contradictory idea. Philosophers have spent their lives in writing volumes drawing out to their painful end all the aspects of these contradictions. But they can never be solved, because they are inherently there. They can never be solved except by understanding how they came there, by understanding that the concept of the thing and its qualities is a fiction invented by the mind for its own purposes, and invented without any great logical skill or philosophical insight. Because the mind which invented it was primitive, because the plain men's minds which still use it in their everyday thought to-day are primitive, for this reason these contradictions are there, and for no other reason. And to recognize this fact is the only possible solution of them.

Sixth Construction: That with the different senses we may perceive the ‘same' objects, and that the worlds of the different senses are, in general, identical with one another.

In front of me is a wall. I see it with my eyes, a yellow shiny surface, as it happens. I stretch out my hand and touch the wall. It feels hard and smooth. That the wall which I see and the wall which I feel are one and the same object is certainly part of the plain man's beliefs about the external world. And it is this belief which is asserted in the sixth construction. The construction refers, of course, to all the senses, not only to sight and touch. We think that the rose which we smell is identical with the rose which we see and touch. We suppose that the bell which we hear ringing is the same object as the bell which we see swinging from side to side. We may say, shortly, that we believe in the equivalence of the senses; and this equivalence is the essence of what is affirmed in the sixth construction.

This belief is very far from being self-evident. It is evident, on the contrary, that the facts, so far as they go, are against it. My visual percept of the wall is a shiny yellow patch. My tactile percept of it is a sense of resistance to my hand. Now a yellow patch cannot be identified with a feel of resistance. The two do not bear even the faintest trace of resemblance to one another. When we identified my red with your red, we at least supposed that my red resembled yours and that, if any mind could perceive both, that mind would perceive the relation of resemblance between the two. But it is not possible to suppose that any mind could ever find a resemblance between a colour and a tactile percept. They have nothing in common except the formal fact of existence or being perceived. The scent of the rose, again, bears no resemblance to its visual appearance or its tactile character. The sound of the bell is totally unlike the look of the bell. The taste of a beaf-steak has nothing in common with its raw red colour.

The identity of the objects of the different senses with one another cannot therefore be perceived. And to suggest that it can be inferred would be idle. For if by the identity of the objects perceived we mean the identity of the actual percepts, e.g. the colour with the sound, the sound with the smell, and so forth, then clearly no inference from our percepts can establish what is plainly contrary to the percepts themselves. If, on the other hand, we mean by the identity of the objects the identity of the 'things’ which underlie the presentations, then too no inference can be drawn. For, as we have already seen, no inference can pass from what we perceive to the supposed 'things' behind them. We cannot even infer the existence of the 'thing', much less its character of identity with some other thing. Hence it is plain that the belief in the equivalence of the senses, being neither perceived nor inferred, must be a mental construction. How then is this construction arrived at?

Suppose that we see an object having a sharp angle or point, say one of the prongs of a pair of scissors. We touch the point and we feel a pricking sensation. We move the pulp of the finger along one edge of the object, over the point, and down the other edge. This gives us a series of tactile and muscular sensations with a pricking sensation about the middle of the series. The acute angle which we see bears no resemblance whatever to the pricking sensation and the other tactile and muscular sensations which make up the tactile acute angle. The reader will remember that John Locke expressed the opinion that a man born blind, who knew by touch the difference between a cube and a sphere, could not, if he suddenly recovered his sight, tell by looking at them which was the cube and which the sphere. Since Locke's day this has frequently been verified experimentally in the cases of persons who have been born blind and were subsequently operated on for cataract. This emphasizes the fact that the visual angle bears no resemblance to the tactile angle. The two have to become associated in experience before they can be identified.

Experience shows that these dissimilar percepts are correlated. It is found that the one is invariably a sign of the possibility of the other. Experience shows that whenever I see a sharp visual angle in an object I can, if I put out my hand, get the experience of the pricking sensation and the other tactile and muscular percepts which make up the tactile angle. Whenever I see a certain kind of red patch which I have come to interpret as a rose, I can, if I scent it with my nose, obtain the familiar odour. Whenever I see the kind of coloured surface which I have come to call a wall, I can, if I put out my hand, obtain the tactile sensation of resistance.

Thus the objects of one sense become associated with the corresponding objects of the other senses. This association goes no way towards proving their identity. But it leads the mind up to the point at which the construction of the identity occurs to it as a simplification.

This step would, however, never be taken if it were not for the previous construction of the 'thing' and its qualities. For it is clearly impossible to hold that a visual presentation is itself identical with a tactile presentation. The two, as we have seen, are wholly dissimilar and exist in different worlds. But when once the mind has come to believe that behind each presentation there exists an unperceived 'thing', it then becomes possible to identify the 'thing' which lies behind the visual presentation with the 'thing' which lies behind the tactile presentation. There will then be no contradiction. It was seen to be contradictory to hold that the circular brown patch is identical with the elliptical brown patch. This contradiction was got rid of by attributing the identity to the 'thing' behind, while admitting the differences between the presentations. In just the same way it is now possible to identify the visual wall with the tactile wall by attributing the identity to the 'thing' behind them while still admitting that the visual percept is different from the tactile percept. If the same thing can, without contradiction, have two visual appearances, one circular and the other elliptical, why should not the same thing have two appearances, one visual and one tactile? Thus belief in the equivalence of the senses is made possible by the fifth construction, and is in fact no more than an extension of the same idea in a different field.

But it is not yet clear why the mind should adopt this construction. In reply to this question we must point once more to the general tendency of the mind to simplify its world and its thought by unifications wherever possible, and thus to reduce the number of objects with which it has to cope. We saw that the many private worlds of different minds were made to coalesce into one. So here, following the same tendency and the same motives of simplification and economy, the several separate worlds of the different senses are made to coalesce into one.
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We need not spend long in describing the logical characters of the sixth construction, for they are similar in all respects to those of the second, third, and subsidiary constructions. Obviously it cannot be proved. You cannot by any conceivable means prove that the wall which you see is the same as the wall which you touch. Experience gives nothing more than that whenever you see a wall, there will also be a tactile wall present to your hand if you put it out. One experience is the sign of another. But nothing can prove that they are numerically identical. They are not. They are different. And it is merely a fiction of the mind to invent a common 'thing' behind the two experiences.

The logical principle on which the sixth construction depends is that existences which make no difference of any kind to our world, whether in the theoretical conception we form of it or in our practical reactions to it, may be ignored and treated as if non-existent. In the present construction we do not indeed treat the objects of any one of the senses as non-existent, but the difference between them is ignored. We do not treat as non-existent either the visual wall or the tactile wall, but we treat the relation of difference between them as if it were non-existent.

Let me say at once that, though I hope to exhibit this topic in something of a new light, I have no essentially novel theory to put forward. For the number of possible views is very limited, and they are well known. They reduce themselves in fact to two main types, both of which have been well represented in philosophical literature, though both admit, of course, of variations of detail in the manner of their presentment. The two possible types of theory are the following. It may be thought either (1) that we have direct and immediate knowledge of other minds, or (2) that our knowledge of them is indirect, being an inference based upon the bodily behaviour of the organisms to which we attribute minds. This latter view may be briefly put thus. I feel my own anger. I am directly aware of my own volitions. I am conscious of my own perceptions. But I cannot feel your anger, see your volitions, or perceive your percepts. I cannot see your red, or feel your anger, any more than I can feel the pain in your leg when it is cut off. I am thus not directly aware of your mind or its contents. I am only directly aware of the existence of your body and its behaviour. I perceive these with my senses, and I infer from them both the existence of your mind and the nature of its particular states. I see your face flush and your brows frown. I infer that this bodily behaviour is probably caused by the fact that you are a conscious being like myself, and that you are angry. I see you smile and conclude that you are pleased. I see you avoid a snake on the path. I explain this behaviour by the assumption that you perceived the snake. I infer generally that the actions of your body are due to your being a conscious mind, and that they are not the result of clockwork or other blind mechanism.

This second type of view is that which was almost universally held by philosophers until a comparatively recent date. The first theory, that of direct awareness, has grown up as a reaction against it, and is now held, in one form or another, by Professor Alexander, Professor C. C. J. Webb, Professor A. E. Taylor, and others.

Before discussing the details of the question at issue I must point out that it makes no essential difference to our theory of knowledge and existence which of the two views is adopted. All that is essential to our theory is to believe that other minds do actually exist, and that we do, in one way or another, come to attain a knowledge of them and enter into communication with them. Provided this is allowed, the construction of the external world as outlined in Chapter VI becomes possible. So long as the solitary mind somehow succeeds in getting into communication with other minds, it and they can then co-operate in building up the external world in the manner there described. Now it is admitted by the partisans of both the rival theories on this subject that other minds do exist, that we do come to have knowledge of them, and that we do communicate with them. Strictly speaking, that should be enough for us. However this knowledge is attained, whether directly or by inference, the fact that it is attained would be sufficient for our theory of the construction of the external world. We might therefore take this as granted by all philosophical schools and proceed with our investigations on that basis.

WE will now return from the consideration of the mind's knowledge of itself and of other minds to its knowledge of the universe outside. We have traced the development of that knowledge from the private and intermittent phantasms of the solitary mind to the establishment of a public external world which is solid and independent, and which exists continuously even when no mind is aware of it. Fleeting private presentations have been replaced by permanent public objects. We had before us, at the close of Chapter VI, something like the ordinary world of everyday knowledge.

But to one important feature of that world we have given no consideration at all. Space and time, even as they appear in common knowledge — and taking no account of scientific concepts of them — do not belong to the world of the solitary mind. We have therefore to consider from what given elements in perception they have been developed, and what course that development has taken.

It must not, of course, be supposed that, because we have first dealt with the development of a public independent world, and only now come to the question of space and time, — it must not be supposed that such is the true order. A public external world is not first established and then afterwards space and time. Neither the logical nor the psychological order could be so represented without absurdity. Actually, no doubt, the two grow up together. Even logically the two developments are so closely interdependent that the separate consideration of them is only possible by means of an abstraction. But in matters so complicated we are compelled, for convenience of exposition, to consider first one branch of the development and then the other. And the order we have chosen to adopt is merely one of convenience.

The problems connected with the philosophy of space and time are so many and so difficult that anything like a complete review of them is out of the question here. Such a review would require at least a separate volume to itself. I shall therefore confine my investigations to only one aspect of the question, that aspect which falls directly in the natural path of our inquiries. My object will be to show that our knowledge of space and time is riddled through and through with mental constructions; or, to put the same thing in a different way, that space and time as we know them are themselves mental constructions. And even my treatment of this one aspect of the problem can be no more than sketchy and diagrammatic, confining itself to the consideration of key positions. I shall detail some of what appear to be the main constructions involved. But I do not deny that there may be many more constructions in our knowledge of space and time besides those here to be laid down.

At once I shall be asked, 'what kind of space and time are you talking about?’ It is now recognized that many kinds of space and space-time are possible, and that more than one kind may be actual in different parts of the universe. Is it Euclidean or non-Euclidean space or space- time that is to be the subject of the discussion? Is it the infinite space which was believed in by the older scientists? Or is it the finite space of Einstein or de Sitter?

I reply that the purpose of this chapter is not to consider advanced scientific ideas, whether of one school or another, whether those fashionable to-day or those which the fathers of our present scientists promulgated. Its purpose is to consider space and time as they appear in the common everyday knowledge of mankind. We have not as yet advanced far enough with our inquiries to begin thinking about science. We are at the very beginning. We have not yet justified even the commonest conceptions of space and time, conceptions such as the existence of empty space, the existence of three dimensions (not to speak of four as yet), the continuity and simultaneity of space, the identity of tactile with visual space, the existence of a common or public space and time. None of these ideas exist in the beginning for the solitary mind. We have to begin at the beginning and develop them. That is the object of this chapter. Something will be said in later chapters of such questions as the Euclidean or non- Euclidean character of space, and the space-time of relativity mechanics. I will, however, say here in anticipation — since it will assist the reader to understand the general point of view adopted — that in my view all kinds of space and time, and of space-time continua, are mental constructions. They are alternative truths, of which the mind may incorporate into knowledge one or other according to its needs, and provided only that it neither contradicts the facts of perception nor the laws of logic.

For our starting-point we must go back again to the beginning, to the world of the solitary mind. Space and time as we now know them will not be found there. But something must be found there out of which space and time must have developed. This something will, of course, be an element of the given. To arrive at the starting-point for our present inquiry, therefore, we have to ask ourselves the question, out of what elements of the given have space and time been developed? What kind of rudimentary or embryonic space and time exist for the solitary mind? What is given to it as immediate and ultimate certitude ? The answer to these questions has already been made fairly clear in a previous chapter. The solitary mind begins, not with any kind of space or time, but with extension-spread and duration-spread.

Our extension-spreads and duration-spreads are private to each of us. The red patch which I see has extension- spread. You see what we afterwards agree to believe is the 'same' red patch. But they are not given as the same. The sameness is, as we have abundantly shown, a later construction. And as the two red patches are not originally the same, so of course the extension-spreads which they carry are not the same. In the beginning therefore my red patch has one extension-spread and your red patch another. They are quite distinct from one another, and they exist in different private universes. It is, of course, the same with duration-spreads. We start, then, not, as is sometimes said, with a multiplicity of private spaces and times, but with a multiplicity of private extension-spreads and duration-spreads.

The next point to note is that even within the private world of each solitary mind there is not a single continuous extension-spread and duration-spread, but a multitude of quite disconnected spreads. The red patch (which may be a pillar-box) disappears from my vision when I look away from it and reappears as a second and distinct red patch when I look again. Since the first red patch is not the same as the second red patch, therefore the extension- spread of the first is not the same as the extension-spread of the second. Nor are the two even continuous with one another. Other presentations with their spreads intervene. Or a period of unconsciousness may intervene. During intervals of sleep or unconsciousness of any sort the spreads disappear along with the presentations, and entirely new ones are created when consciousness again becomes active.

Further, we must not forget that the extension-spread which the solitary mind gets through sight is different from that which it gets through touch and muscular sense. The worlds of touch and sight are separate universes, and the spreads within them are numerically distinct and totally different in kind from one another.

Moreover, though the extension-spread of touch probably has three dimensions, the extension-spread of sight has only two. The visual world as given is flat and without depth. The third visual dimension is, as I shall endeavour to show in detail, a construction. This, of course, is a controversial question, and many philosophers will not agree with me. I shall give my reasons for my opinion later in this chapter.

Empty space, again, does not exist for the solitary mind at the beginning of knowledge. We cannot directly perceive emptiness, pure nothingness. Empty space, or at any rate empty visual space, is a construction. The given extension-spread does not continue beyond the edge of the presentation to which it pertains; or, if it does, it continues only into another presentation. It does not continue into nothingness. Therefore empty space is not given.

For the same reason visual extension-spread does not continue outside the actual present visual field. It is bounded by the limits of the visual field. When I move my eyes round to a new set of objects, the first visual field not only disappears from view, but also, since its esse is percipi, ceases to exist. And its extension-spread ceases to exist along with it, and a new extension-spread comes into existence. For the solitary mind space does not spread out indefinitely into distance beyond what is actually seen. And certainly there is no room in such a mind for infinite space.

These, then, are some of the main characters of our starting-point. From this starting-point space and time as we now know them (whether Euclidean or non-Euclidean, whether finite or infinite) are developed by means of a series of constructions. And I shall now endeavour to set down a few of the main constructions in such order as may appear both logical and convenient. And in this endeavour I must once more guard against misconception. Not only are the following constructions probably not the only ones, but further it is not to be thought that the order in which I have placed them is a cast-iron order which is unalterable. Euclid adopted a certain order for his theorems, and it was a logical order in the sense that theorems which appeared earlier in his book are used as premisses for theorems which appear later. But it is well known that both the proofs and the order might have been different from what they are without detriment to the science. And if this is true of a complete and systematic development of the rigorous science of geometry, how much more will it be true of a series of theorems which profess to be no more than samples of the general procedure of the mind in the development of its knowledge of space and time.

We began with the many private extension-spreads and duration-spreads of the many solitary minds. By means of the eight constructions detailed in this chapter we have advanced to a single continuous public space and a single continuous public time. Visual space which began with two dimensions has been seen to develop three. Empty space has made its appearance. Tactile space has been identified with visual space. Space and time have both become measurable. In a word we have advanced from the rudimentary position of the solitary mind, with its many private perceptual spreads, to the space and time of common everyday knowledge. We have advanced to the space and time which ordinary men conceive as surrounding and containing the universe in which they live.

But the conceptions of equality and measurement which came last in the process of development bring us to the threshold of the more advanced questions of geometry and physics. It is through the seventh and eighth constructions alone that these sciences become possible. These constructions are their foundations. These more advanced questions belong, however, not to common everyday pre- scientific knowledge, but to science itself. And since the aim of this chapter is to proceed only as far as the position of common knowledge, I shall stop here. Questions of Euclidean and non-Euclidean spaces and space-times will be treated under the head of advanced knowledge in Chapters XI and XIV. And I shall have some few observations to offer on the subject of the space-time of relativity mechanics under the head of scientific knowledge in Chapter XIV.

There are, however, two other topics to which I will here briefly refer before closing this chapter. They are (1) the question of the infinity or finitude of space, and (2) the question of fourth, fifth, and further dimensions of space. It is true that neither of these topics belongs to the realm of common knowledge. Both are advanced and, in their scientific aspect, abstruse. But their epistemological aspect, which is all that concerns us, can be quite simply treated. And it will be convenient to make here what brief remarks I have to offer on these subjects.

The infinity of space has been accepted in the scientific world until very recently. Now, under the influence chiefly of relativity mechanics, astronomers and physicists have begun to posit various kinds of finite space. Epistemology is not concerned to decide which view is true. That is a question for the special sciences. Our only interest in the matter is to note that both views alike are constructions. The present issue in the scientific world may be defined as the question which of the two (or more) constructions is true.

The way in which the construction of infinite space has developed is fairly obvious. It depends on the prior construction of empty space. When once empty space has been invented, when once space is believed to extend beyond the edges of objects, there appears to be no reason for supposing that it stops anywhere. Infinite space is thus an inference, not from any perceived fact (in which case it would not be a construction, but a fact) but from previous constructions, especially from that of empty space. Its own existence is therefore constructive.

That the concept of finite space is also a construction will be evident for the same reasons. For a finite space, too, unless it is confined to actual perceived spaces, involves the idea of empty space. Moreover it depends upon other constructions as well. These constructions, which belong to the current body of scientific thought, are more or less abstruse in their nature. But it will suffice for our purpose to point out that finite space is a deduction from certain geometrical 'axioms'. I shall show in the chapter on mathematical knowledge that those axioms which are not analytical propositions are mental constructions. And since finite space is a deduction from those axioms which are constructions, it must be itself a construction.

Which of the rival constructions is 'true' is, as already stated, a question for the scientists. What in general distinguishes a valid or true construction from an invalid one (i.e. from a mere figment of the imagination) is a question for epistemology. But it is a question which cannot be answered until our investigations into the nature of knowledge are concluded. We shall have to face it in a later chapter.

A word, finally, about modern speculations regarding possible four-dimensional, five-dimensional, and n-dimensional spaces. The question is not, it must be carefully noted, anything to do with the four-dimensional space-time of relativity physics. For the fourth dimension in that case is time. It is not a fourth dimension of space. To confuse these two ideas is a common mistake in the popular mind, and one which we must, of course, avoid. The question which we are here considering is that of the possibility of genuine spatial dimensions beyond the third. The attitude of epistemology to the problem is quite simply stated. It is this. The human mind has already constructed the third visual dimension, and has consolidated its position around it. It has become embodied in the everyday knowledge of the mind. It is no longer strange, but is taken as a matter of course. This construction was made necessary in order that the mind might explain its experiences (chiefly the experience of change) consistently with the concept of an independent public external existence. There is not the slightest reason why the mind should not construct any number of further dimensions if they too are found necessary to bring consistency into its knowledge, as that knowledge advances. It is true, of course, that such further dimensions will be inventions. But so is the third visual dimension. And so are the greater number of 'truths' which constitute knowledge. The fourth and further dimensions will be just as 'true' and as 'real' as the third dimension, or indeed as the independent existence of the external world, which is surely the most firmly established of 'truths'.

Such a necessity for constructing further dimensions is now, apparently, beginning to be felt in the physics and astronomy of to-day. And there is nothing impossible in the prediction that the men of some far future date may come to take these further dimensions for granted in exactly the same way as we now take the third dimension. And then a further strange development may take place. The human mind, having long ago constructed the third dimension, forgot the processes of construction. They sank into the unconscious. Hence we now read the third dimension into perception. We imagine that we see distance and depth. Just in the same way the men of the far future, having constructed an n-dimension, may forget the constructions. All the intellectual processes connected with them may become buried in the unconscious. Then those men will imagine that they actually perceive the n-dimension, see it with their eyes, feel it with their hands. And if so, we may expect that the realist philosophers of that time will be misled. They will argue that, because the fourth and fifth dimensions are actually experienced as seen, they are therefore part of the visual given, and that belief in their existence as independent of mind is a 'primitive belief. And any one who says that they were once constructed, and are not 'there' independently of such construction, will be derided in the name of common sense.

There is one consideration, however, which may give pause to these pleasant prophecies. The construction of the third visual dimension took place in the remote past, presumably when man was emerging from the brute, or perhaps earlier than that. It was therefore always unconscious, whereas the present constructions of science are being consciously carried out and recorded. Perhaps for this reason they will not be forgotten.

THE solitary mind was not aware of 'things', but only of presentations and the relations which subsist between them. The only conceptual thought of which it was capable consisted in what we called the 'concepts of the given', i.e. concepts such as 'red', 'sound', 'quality', 'between', &c. But we have now reached a far more developed stage of the mind's evolution. This stage may be briefly characterized by saying that in place of presentations we now have 'things'. Conceptual thought will therefore be enormously enriched. And its general level may be indicated by the phrase 'concepts of things'. It is not, of course, meant by this title to exclude from this stage the concepts of the relations and actions which things have between one another.

There is a certain incorrectness in the initial statement that the mind has now arrived at the awareness of 'things'. For what was constructed in Chapter VI was no more than the general conditions of thinghood, not the details of particular things. Though the sense-world now presents itself to the mind as public, as independent of perception, and as generally consisting of the two strata of 'thing' and 'quality', yet it is still a continuous undivided sense-manifold not yet carved up into discrete things.

The final step towards the familiar and common-sense world of tables and chairs, men and women, horses and stars, is this carving up of the sense-manifold into separate objects. Before my eyes is a many-coloured world. The medley of colours appears to be continuous in all directions both within the visual field and outside it. It is true that the patches of colour have edges, that the green ends here and the red begins there. But though the boundaries of 'things' may often coincide with the boundaries of these colours, this is by no means always so. And we must re- member that the sense-manifold is not only visual, but extends to all the senses. What principles, then, govern the division of the manifold into separate things?

It will be obvious that the carving out of things, and their further subdivision into smaller things, or sub-things as we might call them, is to a large extent arbitrary, and that it varies on different occasions and with different people. The desk on which I am writing may be regarded as a single thing. Or the various pieces of wood of which it is composed may each be regarded as a separate thing, and the whole desk as a collection of many things. Or again we may view each atom or electron in the desk as a complete thing. How we carve up the continuum is thus largely a matter of convenience.

It is, however, subject to certain regulative principles. In the first place, the corresponding presentations of different senses must be grouped together and not separated. The visual sharp angle and the tactile sharp angle (the prick of the skin) must both be assigned to the same thing. If they are separated and assigned to different things, the results will be inconsistent with the fundamental constructions which the mind has setup regarding the external world. In the second place, the spatial and temporal grouping of presentations will be reflected in the grouping of things. This rule is not absolute. But it would not be usual to include in one thing presentations which are far apart in space or time and are separated by a number of intervening presentations. The solar system may no doubt be regarded as one thing, although Neptune is separated from the sun by thousands of millions of miles. But then the members of that system do form, in relation to the fixed stars, a single compact spatial group. In the third place, if any group of presentations are found habitually to move about together relatively to other presentations, i.e. if they always 'hang together', they will usually be regarded as constituting one thing. We pick up a stone and throw it. The whity-brown colour, the shape, the mass, &c, all hang together. So we usually think of them as constituting one thing.

Apart from these general guiding principles the division of the world into things seems to follow the purpose which the particular thinker has in view. We speak of the whole earth as a single thing for the purposes of astronomy, and as millions of separate things for the more general purposes of life.

This free discretion of the mind as to what constitutes a thing, a discretion the exercise of which appears to depend upon convenience and purpose, may well serve as a simple example of the relations which subsist between knowledge and action. It may be urged that the division of the sense-continuum into things at all is only undertaken for the purposes of easy manipulation, and that how it is divided up in a particular case depends wholly upon the particular purpose in view. And the conclusion may be drawn that the test of the truth of any such division is only its success in handling experience. But the conclusion does not follow. For it may equally be held that all conceivable divisions of the sense-continuum into discrete things are equally true, even the quite useless ones, but that the mind selects from among these truths those which suit its purpose.

Leaving this point, we may now assume that the mind whose progress we have been studying has before it the common world of 'things' as we now know it, the world of tables and chairs and houses and stars.

The next necessary step is that the mind should recognize objects of different kinds as what they are. It must be able to say 'This is a tree', 'This is a man', 'This is a star'. It must classify the things which its carving up of the sense-continuum has produced. In other words the formation of the concepts of things becomes necessary.

As to how such concepts are formed it is not either possible or necessary to say very much. They depend in all cases upon the recognition of resemblances and differences. We class together a group of things which resemble each other in definite ways, and the idea of the class is the concept. The mind's power of recognizing resemblances and differences and of founding general ideas upon them must be accepted as an ultimate fact of which no further account can be given.

It is no doubt important to remember that the concepts which we habitually use are not always concepts of what would ordinarily be called 'things'. We also continually use concepts of relations, actions, &c. But in the epistemological inquiries in which we are now concerned I do not think that any harm will be done by our discussion being mostly confined to the concepts of things. Most of what we have here to say of them may be understood to apply equally to the concepts of relations and actions.

The number of resemblances which it is possible to notice among the different members of any random collection of things is indefinitely large. And things may be grouped, or classified, according to any of these resemblances. Therefore the things in any given area of the world, however small that area may be, can be classified in an indefinitely large number of different ways. It follows that the mind has to select from among possible concepts those which it wishes to use. How is this choice determined?

There cannot be any doubt that the choice is determined by the purpose we have in view. For some of the purposes of gardening we may classify plants as weeds, flowers, flowering trees, fruit, &c. The botanist, because his purpose is different, classifies them quite otherwise. The chemist will classify metals according to their chemical characters; the engineer according to their hardness and durability under wear and tear; the jeweller according to their preciousness and beauty; the minter of coins according to their preciousness and malleability; the poisoner according to their capacity for forming poisonous salts; the aeronaut according to their lightness combined with their strength. The librarian classifies books as fiction, poetry, biography, science, &c. The bookseller classifies them as best-sellers and 'the rest*. In all these cases different points of resemblance among the same set of things are selected and made the basis of concepts.

It is sometimes argued from this that the function of the concept is the manipulation of things in action, and therefore that the criterion of the validity of concepts is their success as instruments of action.

It is really saying the same thing when it is argued that the concept is essentially interpretative and predictive. The concept contains a great deal more than what is given in perception. To what is perceived it adds an interpretative element. This element of interpretation enables us to predict future possible experiences, and so to regulate our actions. Suppose I see before me a round yellowy-red object, I recognize this on sight as an apple, i.e. I apply the concept 'apple'. All I see is the colour and the shape. But the concept 'apple' means much more than this. It implies, for example, that the object will taste sweet, will have a white, juicy interior when cut open, &c. Now when I see the round yellowy-red appearance, and when I apply to it the concept 'apple', I am thereby interpreting the visual appearance. And the concept enables me to predict future possible experience in various ways. I can predict, for example, that if I bite the apple it will taste sweet. Thus the reddish-yellow colour and the shape become signs to me that the visual experiences which I have of them will be followed in certain circumstances by another quite different experience, namely, the sweet taste in the mouth. So it is with all such concepts. In front of me is an' extended dull greyish surface. To apply to this appearance the concept 'wall' is to predict the future possible experience of hardness and resistance if I stretch out my hand and touch it; and of pain if I run my head against it. To recognize a small buzzing black and yellow object as a 'wasp' predicts the future possible experience of being stung if I irritate it.

All this is really implied in what was said in the previous paragraph about our choice of concepts being determined by the purpose we have in view. The jeweller classifies metals by their rarity and beauty. The concept 'gold' implies for him that the qualities by which he recognizes gold are signs of the possible future experience of selling it at a high price. The same concept 'gold' means for the engineer that the qualities by which he recognizes it are signs that he will never be able to use the substance as an engineering material. Thus the application of a concept means that the perceived characters A,B, C, D are taken as signs of the unperceived characters M, N. It may be that M is relevant to my purpose, while N is relevant to yours. In this way the concept guides the actions of both of us in the carrying out of our special purposes.

From considerations such as these the inference is drawn that the concept is nothing but a device of the mind for enabling the organism to attain success in action. And since the function of the concept is only to help forward successful action, it would seem to follow that the only validity the concept can have must reside in its successful fulfilment of this function. To say that a judgement or a concept is 'true', therefore, can mean nothing but that it 'works' in practice.

These conclusions do not follow from the premisses on which they are supposed to be based. As far as the premisses are concerned there is nothing seriously wrong. Not only will we admit that concepts are now used by the mind as guides to action in the manner described. We will lay it down, further, that in all probability conceptual thinking would never have come into existence on the planet but for the pressure of biological necessity.

Let us dwell a little upon this question. We must first make clear the distinction between free and submerged concepts. When we see an apple, recognize it, and eat it, we do not necessarily place before our minds the abstract idea or concept of 'apple'. There does not pass through our minds the explicit judgement 'This is an apple'. Without any such judgement or abstract thinking the fruit is recognized as what it is, and the reaction of eating follows. The act of recognition, however, implies some kind of unrealized conceptual operation of consciousness. But it is a part of the act of perception, not a free thought in the mind. In such a case we say that the concept is implicit or submerged in sense-perception, and that it has not risen to the level of a free concept. When, on the other hand, we think abstractly about the concept 'apple' it is then a free concept.

If any one objects to our description of the act of ordinary recognition as involving an unrealized, implicit, or submerged concept; if it is said that a concept is in essence an abstraction, and cannot be said to exist except as an abstraction; I shall not argue the question. It will be sufficient for our argument here if it is admitted that in all probability the genuine or free concept has evolved; that it took its starting-point from the act of recognition ; and that the process of comparison involved in the act of recognition may therefore be legitimately regarded as in some sense potentially conceptual — since it actually developed into the concept. I shall continue to use the distinction between free and submerged concepts meaning no more than this.

All abstract thinking and reasoning depends upon the presence of free concepts. A performing dog can probably be trained to recognize the difference between a wooden triangle and a wooden circle, and to react differently to each. We should say, then, that the concepts of triangle and circle must be implicit or submerged in the canine consciousness. But the dog would be incapable of geometry. Geometry only becomes possible to a mind in which the concepts of triangle, circle, &L, have freed themselves from their immersion in the concrete and have become abstract. We assume that animals are not capable of any high degree of free abstraction. …….. The doctrine of evolution has made us suspicious of sharp lines between the animal and the human. Human powers of abstraction must have evolved out of potentialities latent in the minds of our animal ancestors. And it would therefore seem unsafe to deny that there may be in some animal minds some faint glimmerings of the abstract. But even so, these glimmerings cannot amount to much. And I think it will be both safe and relevant to our inquiry to say at the lowest that, roughly speaking, the power of using free concepts is a special and noticeable characteristic of man which appears to be more or less absent from the animal mind.

Now when we say that conceptual thought could never have come into existence but for the pressure of biological necessities, we are, of course, thinking primarily of free concepts. But it will strengthen the case for an evolutionary view of knowledge if we can trace free thought back to its origin in submerged concepts. Before men attained high powers of abstract thinking, their human and pre-human ancestors must first have acted by the light of submerged concepts. Not only men, but animals also, recognize objects. Men and animals alike recognize their food, their enemies, their mates, and so on. In the act of recognition what we have called submerged concepts are involved. And it is surely a reasonable supposition that the free concepts of the human intellect must have been developed out of the submerged concepts of our ancestors. Such an evolution would be no more than the making explicit of what was implicit. But the use of submerged concepts takes place only in the act of recognition. Therefore it is a reasonable hypothesis that all concepts, that is to say all abstract thoughts, have developed out of the germ of them which exists in the psychological act of recognition.

Now recognition is obviously a mental power which was developed under pressure of biological necessity for the purpose of fulfilling definite functions in the life of the organism. From the very dawn of life there must have been something which dimly corresponded to the act of recognition. The lowest organisms must in some faint and instinctive way have selected from, or concentrated upon, certain parts of their environment. And when we come to the higher forms of animal life, the acts of recognition which we find seem essentially similar to our own. The mammal clearly recognizes its food, its mates, and other objects which are of practical concern in its life. And it is obvious that it has developed this mental power for practical ends, and not from any thirst for 'knowledge' or 'truth'.

When we rise to the consideration of the power of using free concepts, two propositions present themselves which would appear to be fairly certainly true. The first is that this power of abstract thought must have been developed for exactly the same practical reasons as caused the development of the act of recognition. The practical functions of free concepts are the same as the functions of the act of recognition. The second proposition is that the power of free concepts came into existence in the evolution of the race because it possesses marked advantages over the bare power of recognition. Individuals which showed any tendency to possess the power of free thought therefore survived and propagated their kind.

These points will both become clearer if we ask ourselves the questions, why we think in concepts at all, and what advantage the method of free concepts has over the method of bare recognition with its submerged concepts. The answer to the first question is that the function of free concepts in practical life is the same as the function of bare acts of recognition, namely to enable the organism to distinguish the various helpful and harmful elements of its environment and to react to them in the most appropriate manner. The next point is that in carrying out this function the method of the free concept is in every way superior to the primitive method of bare recognition. The method of recognition is very limited in its scope and is liable to mistake. The organism must be able to distinguish its enemies from its friends. Any stratagem which its enemies develop may deceive it. And in the long run the only method of being sure is to develop and use the power of abstract thought. They majority of stratagems by means of which primitive man entraps either animals or his human enemies rely precisely on the hope that his victim will not think, i.e. will not use the free concept, but will act blindly on the method of recognition. A poison is substituted for good food, and is made to look like good food. The whole intention is that the victim shall be misled by an erroneous act of recognition. The victim recognizes as good food by its mere appearance what is in fact poison. The only way in which such error can be avoided is by developing a more powerful method of distinguishing that which will advantage us from that which will harm us. And that more powerful method is the free concept.

Leaving savages behind, we may illustrate this point more easily by turning to our own more advanced mental life. The method of bare recognition is often good enough for us. I recognize my brother on sight. I recognize an apple placed on the table for dessert. But if it happens that any doubt arises as to what an object is, it has to be settled by the method of the concept. This method depends upon the fact that the concept of a class of objects attributes to that class a number of qualities other than those which, in any particular case, are being perceived. We see a red round object and call it an apple. The redness and roundness is all that at the moment we perceive. But our concept of apple attributes to it numerous other qualities which at the moment we are not perceiving, such as its taste, its aroma, its juiciness, its interior softness or hardness, &c. Our actual perception of an object may be confined to experiencing the two characters of the object A and B. But the concept of the object attributes to it other qualities, and may be represented by the expression A BCD . . . N. If then we perceive only AB the method of bare recognition jumps to the conclusion that the object is an ABCD . . . N. This conclusion may well be a fatal mistake which may cost the organism its life. For there may be another class of objects which is represented by the expression ABPQ ... X.The organism perceives only AB and jumps to the conclusion that the object is an ABCD . . . N, whereas it is in faet an ABPQ ... X This is what happens when the rat mistakes poison for good food.

……… Something red and round is presented to me. I cannot distinguish its appearance from that of an apple. But I suspect that it may be one of those India-rubber imitations of apples which one buys for the purpose of playing a joke on one's friends. I therefore try to cut it open with a knife to see whether it is easily cut and whether its inside is white, juicy, &c. I may further taste it to see whether it is sweet. If it satisfies the necessary tests, I subsume it confidently under the concept 'apple'. The chemical analysis of substances proceeds on exactly the same principle, except that the qualities used as crucial tests are as a rule more remote from popular knowledge.

If we are not sure how to distinguish between a number of things, the only sure method is to get hold of good definitions, i.e. concepts, of the classes to which they might belong, and ascertain which definition each object satisfies. But this is only possible if we have before our minds the abstract idea of the classes, i.e. free concepts. This is the method of the free concept.

The power of abstract thinking must surely have been evolved out of the act of bare recognition. And it must have resulted from experience of the fatal mistakes which may arise from a blind reliance on the method of bare recognition. That method consists in taking account only of the immediately perceived characters of the object. When the danger of this is brought home to the organism by bitter experience, there will be a tendency to attempt to associate with the perceived characters of the object a number of unperceived characters. ‘Apple' comes to mean to the mind not only the round and red appearance which is the perceived character sufficient for bare recognition, but also a white juicy interior, a sweet taste, and a number of other characters which are usually unperceived when the object is first seen. As soon as the meaning of 'apple' comes to include unperceived characters, it is clear that the meaning is being lifted out of the plane of perception into that of thought. The freeing of the concept from its submergence in the concrete has begun. And with the evolution of the free concept we have passed above the level of mere consciousness and reached that of mind or spirit.

These considerations seem to establish beyond doubt the contention that conceptual thought has been developed as an instrument for executing the practical purposes of life. And when one comes to think of it, one could scarcely hold any other view. For not only has the history of thought in the past been largely dependent on practical purposes, but even now nearly all thought is directed to practical ends. Even those who are eminent for their powers of abstract thinking, scientists, mathematicians, and philosophers, yet spend a very great part of the twenty-four hours using their minds as instruments towards the practical activities of food-getting, travelling to and from their places of avocation, arranging for shelter, clothing, and the rest. And the average plain man uses his power of conceptual thinking almost exclusively in the service of practical ends. No one, except the stage caricature of the professor unable to see beyond the windows of his classroom, would suppose that mind exists only for the purpose of doing higher mathematics and learning Greek. The amount of conceptual thought which is, on the planet, directed towards 'knowledge for its own sake' must be extremely small, almost negligible in comparison with the amount expended on practical activities.

In favour of the pragmatic view of knowledge we have, then, three facts, (1) Concepts have been evolved by the organism for practical purposes. (2) They are still mainly used for practical purposes. (3) Their inner structure proclaims their practical import. For they are predictive. And their predictivity has for its. function the guidance of actions.

I have put these facts as strongly and fully as possible in order to do justice to a view with which I disagree. Is the inference justified which some philosophers draw from these facts, the inference, namely, that the concept has no validity except that which it derives from its usefulness in practical action ? I do not think so.

If, in the first place, we cast our minds back to what was said on an earlier page regarding a similar topic, we shall remember that the mind, faced by practical problems, selects those resemblances among its experiences which seem likely to help it, and erects them into concepts. It leaves alone those resemblances which do not appear to be helpful. This explains why nearly all commonly used concepts have the mark of practicality. Things in a given area of experience may be classified in an indefinitely large number of ways according to what resemblances are used as the basis of the classification. From the possible classifications the mind selects those which are useful for its own particular purposes. And the classification which is useful for one purpose may be unsuitable for another. That is why the jeweller, the engineer, and the mint-master classify metals in quite different ways.

From this it appears that the usefulness of a concept is not the same thing as its truth. A concept is true if it is based upon a resemblance which actually exists in the field of experience. And the resemblance may be entirely useless for any human purpose.

All that was said on this matter when we were considering the concepts of the given is equally true of the concepts of 'things'. The principles are exactly the same. As a rule we collect things into classes which are useful to us. But the validity or truth of the classification depends in no way upon this utility but upon whether the resemblances on which it is based are real and have been correctly noted. All concepts correctly based upon real resemblances are true. But some such concepts might well be useless for any ordinary human purpose. Others, the majority, are useful relatively to some purposes and useless relatively to others. The jeweller's classification of metals is useless to the engineer, and the engineer's classification is useless to the jeweller. But they are both true.

When we considered the concepts of the given we saw that those concepts are constructed by the mind in no arbitrary fashion. They are tied to the given. The given is the irreducible stubborn kernel of knowledge which the mind can neither make, alter, nor destroy. The concept 'red' is determined by the relation of likeness between two red patches. The mind does not create, but discovers, this likeness. The concept could not be otherwise than it is, whether useful or useless. Its validity does not depend upon whether it advances any human purpose, but only upon whether the resemblance has been correctly noted.

It is exactly the same with the concepts of 'things'. There is only one difference between the concepts of the given and the concepts of things which is of importance in the present connexion. That difference consists in the fact that concepts of things possess the character of predictivity, while concepts of the given do not. This was pointed out in Chapter IV, and it is only necessary now to remind the reader of the point. To classify an appearance as 'red' predicts nothing. To classify it as 'apple' predicts a sweet taste. (No doubt it might be said that to classify it as red predicts that a certain frequency of vibration will be shown on an indicator, or that it will come out black in a photograph. But this is not knowledge contained in the bare concept itself. Any one might know what 'red' means without knowing either of these facts.)

Possibly this indicates that the pragmatic element finds itself more at home among the concepts of things than among the concepts of the given. But it makes no essential difference. The concepts of things are predictive and are used as guides to action. But this does not constitute their validity. Their validity consists in the reality of the relations of resemblance which they assert.

Our general conclusion is that the concepts of things, like the concepts of the given, are tied to the given, and determined by it, and that the mind only selects from among all possible true concepts those which are useful to it.

It may be thought that this will commit us uncomfortably to the 'correspondence' theory of truth, or the 'copy’ theory as it is sometimes called. I must answer, firstly, that it is far too early for us to draw any conclusions as to the general nature of truth. Many further aspects of the problem must be investigated before we can formulate a solution. But secondly, if we must, tentatively and provisionally, give at this point some rough indication of our bearings in regard to the correspondence theory, I would say that there is an element of truth in it. The truth of a judgement is in some way determined by the given. There must be in some way a correspondence between the given and the thought. But I would remind the reader that the externality of the world, its independence of mind, is itself a creation of the mind. The usual embarrassments of the correspondence theory, therefore, can scarcely touch us. That theory is impossible and untenable if it is supposed that thought is a copy of something absolutely independent of and outside thought in the ordinary realist sense. But we do not adopt the absurdity of supposing that our perceptions are images of something unseen and unknown beyond or behind them. There can be for us no talk of a correspondence between something inside the mind and some- thing outside it. If there is any kind of correspondence involved in the notion of truth, it will not be between our percepts and an unperceived 'thing' behind them. It will be a correspondence between the percept and the concept. And the correspondence between percept and concept is not the relation of copy to original. Percept and concept are, in that sense, incommensurable and wholly unlike each other, since the percept is individual and the concept universal. A concept corresponds to a percept when it is a concept which correctly applies to that percept. The proposition 'This is red' is true if the concept 'red' agrees with the percept, i.e. if the percept is red. But if the concept 'red' is misapplied to a green percept, then the resulting proposition is false. These remarks are to be taken as merely preliminary and tentative, and I shall leave the question at that for the present.

The course of our inquiry so far lends no countenance to the view that the validity of a concept resides wholly in its success as an instrument of practical activity. This is not true either of the concepts of the given or of the concepts of things, the two logical stages of the concept so far examined. And we begin to suspect that such a view rests upon an elementary confusion. It is true that the concept must have been evolved, under pressure of biological needs, for practical ends. It is true that the function of thought in the world to-day appears to be rather that of an instrument of action than that of a means to 'pure’ knowledge. Most men, that is to say, use their powers of abstract thought in practical rather than in theoretical interests. But because truth is useful it does not follow that its truth consists in its utility. Did not Bacon long ago sum up in three words all that can legitimately be said as to the relation of knowledge to action? 'Knowledge is power.' Knowledge enables us to do things. Bacon did not need either the doctrine of evolution or the teachings of the pragmatists to convince him that the concept is a valuable instrument of successful activity. But it never occurred to Bacon to suggest that, because it is often useful to know a true proposition, therefore this usefulness is what constitutes its truth.

…… What is meant by such agreement and disagreement, or how agreement and disagreement between concept and percept are possible? To these questions there is, in my opinion, no answer, for the reason that we have reached rock bottom. These conceptions are ultimate facts of consciousness. They cannot be analysed into anything simpler (or more learned and elaborate, if that is what is demanded). They cannot be further explained in terms of anything other than themselves. That my judgement 'This is red' may either agree or not agree with my percept; that Wien I have a sensation, I may either make a judgement which does correspond with it or one which does not; that if I see green, but say 'This is red', there is then a failure of my judgement to correspond with my percept; these are ultimate facts. If they are not admitted and understood, nothing further can be done to prove them or make them intelligible. We can no more say why there- should exist such correspondence and lack of it than we can say why presentations exist, or why minds exist, or why one presentation bears the relation of resemblance to another, or why there are concepts in the mind.

…….. the judgement 'This is red' really asserts the existence of the relation of resemblance between 'this' and other presentations which have previously been called red. If this is true, i.e. if this resemblance actually exists, then we have applied the right concept. If it is not true, then we have applied the wrong concept. Hence if we say that the truth of the judgement consists in the application of the right concepts to the facts, or to the percepts, this will mean exactly the same thing as saying that the truth consists in a correspondence between the concept and the percept.

It is obvious, I think, that in the kind of 'correspondence' here asserted (i.e., that the truth of the judgement consists in the application of the right concepts to the facts, or to the percepts,) …… is not that fatal fallacy which has so often been noted in most correspondence theories of truth. The essence of those theories consisted in supposing that truth lies in the correspondence of our perceptions with things which were believed to lie outside our perceptions in the external world. And it was evident that whether or not our perceptions agreed with outside things could never be known since we can inspect only our percepts and not things as they exist outside our percepts. That was the fallacy of the old correspondence theory of truth. … in the theory now presented no such fallacy occurs. A correspondence is alleged to exist between our percepts and our concepts, both of which are open to our inspection and comparison.

…… whether the percepts concerned in the judgement are present, future, or past, makes no difference to the theory of truth. ……… No doubt there are difficult problems involved here regarding the nature of memory and imagination. ……. The formula of the correspondence of concept and percept as the essence of the truth of these kinds of elementary perceptual propositions is thus equally correct whether the propositions refer to the present, the past, or the future.
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Concepts of things are, as we have seen, essentially predictive of future possible experience. I see a red round patch and I say 'This is an apple'. The meaning of this is : if I bite the red patch, I shall experience a certain sweet taste; if I feel it, it will be soft; if I cut it open, it will appear whitish; and so, on. The judgement, it is evident, will be true if these various predictions are true. The predictions, however, when analysed into their simplest elements, are merely judgements in the future tense which apply concepts of the given to the presentation. They say 'If I bite it, this will be sweet’, or 'if . . . this will be white, this will be soft’, and so on. It is true that the 'if’ clause introduces the construction of possibility, and other constructions connected with thinghood, a public world, &c, may be involved. These, of course, would take the judgement into a much higher sphere of knowledge than that which we are now considering. We can for the present neglect these constructive elements of the judgement, since we shall be considering the whole question of the truth of constructions a little later. And if we thus neglect these constructive elements, it is clear that the truth of the judgement 'This is an apple' consists solely once more in the correspondence of the judgement with the percepts. The judgement is true if it turns out correct that the inside of the apple is white, sweet, and the rest. We do not need, therefore, as yet to go beyond the simple formula of the correspondence of concepts with percepts to find the essence of the truth or falsity of this kind of judgement.

It is at this point that we can solve the problem of illusion, so far as it is a problem of epistemology. An illusion occurs when we interpret a presentation wrongly, i.e. when we apply to it the wrong concept of things. I see a faint object in the distance, and take it for a man. On going nearer I find that it is a tree stump. Why I make this mistake is not a question for epistemology, but for psychology. It may be due to carelessness, lack of clear vision, mental confusion of one kind or another. With that we are not concerned.- The epistemological character of the illusion consists in the fact that we have applied the wrong predictive concepts to the presentation. There is a lack of agreement between the concepts and the future percepts. There is, therefore, nothing new here to be investigated.

If the judgement whose truth is under consideration is, say, 'This apple is red', it is clear that the epistemological analysis already made of such propositions as 'This is an apple' will apply with merely the necessary minor modifications. There will be no change in principle. The entire truth of the judgement, apart from its constructive elements, will reside in the correspondence of concepts with percepts. For the judgement 'This apple is red' tells us that 'this is an apple' and that 'it is red'. The first of these two statements is identical with the judgement whose truth we found in the paragraph before the last to consist solely in the agreement of concept with percept; and the second 'it is red' also plainly requires no further analysis.

We may now advance one step further to general and abstract propositions. For 'This apple is red' we substitute judgements such as 'All apples are pleasant-coloured', or 'All matter is heavy', or 'Most Englishmen are fair- skinned'. The truth of all general and abstract judgements lies in their applicability to particular cases. We have seen that once and for all in connexion with the case of mathematics. So that, if we still ignore the constructive elements, the truth of these general judgements lies in nothing but the correspondence of concepts with percepts.

Let us take as an example a very highly abstract judgement, namely Newton's law of gravitation. We will consider it purged of the concept of force. For force is, in the first place, a construction, and in the second place an invalid construction. So that it would complicate our inquiry from every point of view for us to take° it into account. Instead, we will think of Newton's law as no more than a formula stated in terms of its essential factors, such as time, mass, distance. Now although Newton's law makes no direct assertions about particular percepts — as it would do if it said, for example, 'This planet is now visible at this spot' — although it is abstract, yet its whole meaning and truth reside in the end in its applicability to percepts. It is a general formula or recipe from which can be drawn particular statements about particular facts of perception. That is its sole function and use. We can deduce from it the position of Mars at midnight on 1 January 1950, the times and dates of solar and lunar eclipses or of a transit of Venus, and so on. The correctness of these deductions consists in the agreement of them with what is actually perceived, i.e. in the correspondence of the concepts with the percepts, and the truth of the law is nothing but the correctness of the deductions made from it.

It is true, of course, that we get cases in which it is said that true deductions follow from a false law. It is a commonplace of the logic books that a hypothesis may cover all the known facts and yet be false. But it will be found in all such cases that the law is not a mere generalized statement of what happens, containing nothing except the very deductions which are made from it wrapped up in pill form, but that there is always in the law which is thus found false some other element, usually a constructive element, which is false, and which poisons the supposed law with its falsehood. ………

It begins plainly to emerge that in most judgements there are two elements, the factual and the constructive. A statement may be wholly factual, such as 'This is red'. Or it may be wholly constructive, such as 'ether exists'. Or, by far the commonest case, it may be a mixture of the factual and the constructive. Practically all ordinary judgements belong to this mixed class. This will be evident when we consider that the very existence of a public world of 'things' is a construction, so that all judgements which rise above the level of mere statements that we have some particular sensation such as redness contain a constructive element.

It is also becoming plain that the truth of the factual part of a judgement always depends solely upon the correspondence of concepts with percepts. We may generalize and say that all judgements about the external world are judgements whose truth resides in the correspondence of concepts and percept so long as we ignore the constructive element. What are the conditions of the truth of mental constructions is a question which we have still to discuss.

But before leaving the present topic I will give one or two more examples to make matters clearer. No one has ever seen an electron. But if we assume the existence of electrons and of the laws which are believed to govern their activities we can then make deductions which agree with our actual perceptions. These perceptions may consist in the visual readings of the position of a pointer on a dial, or in feelings of heat, or in the readings of a thermometer, or in the perceived behaviour of any material object. If the deductions are correct, then we have a correspondence between concepts and percepts. This correspondence does not alone prove the truth of the theory, for as we already noted, there may be constructive elements in the theory, and owing to this fact correct deductions may always follow from false theories.
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………if we turn to judgements about non-physical things, we have of course to substitute for physical percepts the internal awarenesses by the mind of its own states. To use the word percept for our awarenesses of our own states would not be incorrect; but it is apt to mislead owing to the fact that it is more usually confined to the physical sphere. ……… It will be better, however, in the final statement of the theory to substitute for the word 'percept' the word 'given'. The 'given' covers both the internal and the external worlds. My emotions, thoughts, &c, in so far as I am aware of them, are as much givens as are the red patches and sounds of the physical world. Moreover, if we use the word 'given,' this will make it clear that all constructive elements are excluded. We may therefore sum up this part of our theory by saying that all judgements are either factual or constructive or both; and in regard to all factual judgements, and all factual elements in mixed judgements, their truth consists solely in a correspondence between concept and given. Before passing to the question of the validity of constructions — which is the next main point on our programme — it will be convenient here shortly to consider the place of logic in the theory.
Nothing can be true if it involves a breach of the laws of logic.
A single judgement cannot by itself, however, involve such a breach. For every illogicality must in the end boil down to a contradiction or inconsistency between two judgements. Therefore there must be at least two judgements to make an illogicality. …… Hence questions of logic do not arise for single truths, but only for systems of truths, a system being constituted by at least two judgements. ………….

We have already seen many times that two incompatible judgements may be alternative truths. ………….
………. Two contradictory propositions may both be true, but not in the same system of truths. ………

It will now be convenient to consider the problem of the validity of mental constructions. A construction is a fiction, a judgement invented by the mind without any foundation in fact (i.e. in the given). That being so, it is evident that, unless strict conditions are laid down as to precisely what constructions are to be allowed within the fold of truth, we shall be reduced to the pass of allowing any wild figments of a diseased imagination to pose as truths. We might be compelled to believe in salamanders and goblins, in magic, in charms, in the man in the moon. These are all certainly in a sense 'mental constructions’. But they cannot be accepted as truths. We have therefore somehow to distinguish between those constructions which are true and those which are false. In other words we have to find the criteria of the validity of mental constructions.

It is clear, in the first place, that constructive truths, like those which are factual, are subject to the laws of logic. A single constructive judgement cannot, for reasons pointed out in the last section, be either logical or illogical. But not only are systems of constructions common, but even what would ordinarily pass as a single construction can usually be analysed into several judgements. We may therefore lay it down (1) that a construction must be internally self-consistent, and (2) that it must be consistent with the system of truths into which it is sought to embody it. These conditions will serve to eliminate a vast number of otherwise possible constructions. They will invalidate belief in the man in the moon because such a belief is inconsistent with many accepted truths such as that there is no atmosphere in the moon which men could breathe.

Our next step must be to investigate the relation of constructions to the given, i.e. to facts, to actual percepts, and so on. We laid it down very early that all truth is tied to the given. We shall find that this applies as much to constructions as to factual truths. But it cannot mean, in the case of constructions, that there is an actual correspondence of the judgement with the given, for the very essence of the construction is that it is not a fact and that no given corresponds to it. We judge that the table exists unperceived, and we consider this to be a truth. But the unperceived table can never be given. In other words there is no given which corresponds to the construction of the unperceived table.
Constructions, however, are tied to the given in the sense that if any deductions from them disagree with the given, the constructions must be false.
For it commonly happens that the very purpose of a construction is that we may be able to deduce from it judgements which are not themselves constructions but factual propositions. This is practically always the case with the constructions of science. ……….. in the case of scientific constructions … Their purpose is to 'explain' actual facts, and to predict future ones. The 'explanation', it need hardly be said, does not aim at telling us the 'why' of anything, but only the 'how'. It consists only in being able to deduce the many facts from one concept, i.e. to subsume the particulars under a universal, to discover a law. The universal concept which is assumed as the explanation of the facts may be a construction. And it is then a condition of the validity of the construction that the deductions from it shall agree with the facts, i.e. that in them there shall be a correspondence between the concepts and the given. For example, an electron is a construction. But the theory of the electron agrees with the facts in the sense that deductions from it agree with our actual perceptions. If deductions from it clashed with the facts of perception, we should have to conclude that the construction is false.

If we express this relationship of constructions to the given by saying that if any deduction from a construction clashes with the given, that construction is invalid, this will be found to be a universal condition of the validity of constructions and to apply, not only to scientific constructions, but to all. Take the construction of the unperceived table. As already pointed out, we do not make elaborate deductions and predictions from it. That is not its purpose. But still it is nevertheless the case that, if any deduction from this or any other such construction were found somehow to clash with actual perceptions, we should have to reject the construction. We are enabled to believe in the unperceived table precisely because to do so makes no difference to the facts, i.e. does not clash with them.

Hence all constructions are limited by the two conditions that they are bound (1) by the given, and (2) by the laws of logic. These are not, however, the sole conditions of their validity. For we might invent all kinds of fanciful figments of the imagination which would be logically feasible and also not clash with any known facts. Therefore there must be some other condition of the truth of a construction. This further condition is that the construction must be necessary for the purposes of knowledge. That is to say, we cannot admit as valid any constructions which are unnecessary and superfluous. Under this canon we shall refuse to allow the mind to multiply all kinds of fantastic agencies and existences which may perhaps not clash with the laws of logic nor with the given, but which we should nevertheless declare unreal.
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But what is meant by the phrase 'necessary for the purposes of knowledge'? It is clearly essential that it should not be left vague. The question resolves itself into two: (1) What kind of 'necessity' is intended? (2) What are 'the purposes of knowledge'?

As to the first question, it is clearly not logical necessity that is meant. There was no logical necessity to reduce the many worlds to one public world, to assume the resemblance of your red to my red, to invent the third visual dimension of space, or to suppose that the table goes on existing when no one is aware of it. That it is not logical necessity that is involved follows indeed from the very definition of a construction. …………
The 'necessary’ here means simply what is required. It is the simple and homely notion of what we need for our purposes, Le. for the purposes of knowledge. We assumed the single public world because it was convenient, because it helped thought, because we needed it for the purposes of thought. The same will be found true of any construction whatever. This will, I think, suffice as an explication of the kind of 'necessity' involved in constructions.

Next we have to inquire what are 'the purposes of knowledge'. I cannot see that any single all-inclusive answer can be given to this question. Philosophers are too much in love with such simple answers. One school emphasizes the practical necessities of the physical organism, another the spiritual ideal of pure knowledge. Why it should be supposed that the truth can be summed up in a single concept I do not know. And it seems clear in the present case that both of the answers just mentioned are partial truths.

At the beginning of the evolution of mind practical needs will hold exclusive sway. The crocodile has no ideal of knowledge for its own sake. Even the average un- educated human being has very little, and thought for him is mostly practically conditioned. It may be taken as certain that the main necessities which led to the early development of knowledge, and therefore of mental constructions, were strictly practical. A single world was originally assumed, not as a truth for its own sake, but because it rendered communication and co-operation between organisms easier, and because minds hungered for the society of their fellows. Communication could have been carried on, as we have shown in an earlier chapter, on the basis of a multitude of private worlds. A single world was assumed because it was easier and simpler. In the last resort, ease and simplicity of thought are preferred to labour and complexity because the mind's energy is limited, because, if you like, the mind is lazy. Similar considerations apply to all the early constructions of the human mind.

Later constructions, such as those of science, are similarly conditioned, because of two possible constructions we prefer the simpler. But the elaboration of such constructions is undertaken for two reasons. Firstly, they are forced onus by logic, by the fact that, having once created constructions, we are compelled to invent others in order to maintain consistency. This process has been fully illustrated in previous chapters. When once we have invented the idea of the atom, logic, together with new facts (i.e. new perceptions) which appear inconsistent with the older forms of the theory of the atom, will force us on to later forms of the theory, to the construction of the electron, &c. Secondly, there grows up a desire for knowledge for its own sake. Curiosity is aroused. This forces us to carry on the process of constructing new truths to fit in with the old.

The statement that some truths, namely, for the most part, the earlier constructions of the mind, are created to meet practical needs, is not an admission of the pragmatist position. It is indeed the element of truth which that position contains. But the pragmatist position as a whole is false because (1) all truth, whether factual or constructive, is tied by the given, and because (2) it is tied by the laws of logic. Both the given and the laws of logic are absolute, are forced upon us ab extra, whether we like it or not, whether it suits our convenience or no. This is true whether we interpret convenience as meaning convenience for the purposes of practical action or of theoretical thought. Truth, therefore, is not whatever we will to believe. Nor is the will the sole arbiter, as the name ‘voluntarism' would seem to imply. Truth is compelled both by facts and by logic. The elements of truth in pragmatism are as follows: A part of truth is constructive, and constructions may be moulded by the will, i.e. by considerations of either practical or theoretical needs, within the limits laid down by fact and logic. But the truth of purely factual judgements, and of the factual elements in mixed judgements, is entirely independent of pragmatic considerations. It is also to be admitted, however, that even among factual truths the mind selects those which are useful or convenient to it. And as between two or more alternative truths it chooses the simpler for reasons of convenience. The pragmatic elements in knowledge are, therefore, three- fold, (1) free construction within fixed limits, (2) selectiveness, and (3) simplification for ease and convenience.

The element of truth in the 'correspondence' theory is that all factual truths are in fact true by virtue of a correspondence. Not the correspondence, however, between external thing and perception, but between concept and given. Moreover even in constructive truths correspondence is involved in that a disagreement between the implications of, or deductions from, the construction and the given renders the construction false.

The element of truth in the 'coherence' theory is that knowledge constitutes a system of judgements which must be logically coherent, which must be consistent with one another, which must obey the laws of logic.

Any judgement, therefore, is true
(1) if it is a bare statement of what is given, and if in such statement the concepts correspond with the given;
or (2) if it is a valid construction, i.e. a construction which (a) involves no implications which are contradicted by the given, and (b) is required or necessary for the practical or theoretical purposes of knowledge;
or (3) if is a combination of the above two.

This is the definition of the truth of single judgements. If more than one judgement is m question a further condition is involved, namely (4) in systems of truths the laws of logic must be obeyed. This includes the condition that a complex construction, i.e. a construction which is a compound of more than one judgement, must be internally self-consistent.

It will be observed that no special mention is made of universal, general, or abstract judgements. This is because they are regarded merely as a multitude of individual judgements telescoped into one. The same conditions of truth, therefore, apply to them as to individual judgements.

The majority of judgements come under head (3). They are combinations of factual and constructive elements.

The definition of error is the opposite of that of truth. Any proposition which does not conform to the above conditions is false.

It may rightly be asked whether this definition implies belief in 'absolute' truth, i.e. whether it involves that a judgement once true is always true, that if it is true at all, it is true at all times and for all purposes. Or does our theory, on the contrary, imply the pragmatist doctrine that a judgement may be true for the purposes we have in hand, but false when our purpose changes; or true in one age and false in another?

The answer is plainly that our theory implies belief in absolute truth, and is therefore in agreement with the view always taken in the past by common sense. It will be best to make the issue clear by thinking in terms of a specific example. Suppose that there is one theory of the atom which is accepted in 1932 because it explains all the known facts. We will call this theory A. Suppose that in 1942 a new set of facts is discovered which definitely clashes with theory A and necessitates the elaboration of a new theory B. In 1952 this may again be upset by the discovery of new facts and the establishment of a third theory C; and so on.

What are we to say regarding this series of theories? The pragmatist will say apparently that theory A was true in 1932, but became false in 1942. Common sense and the theory of 'absolute' truth say, on the contrary, that if theory A was proved false in 1942, it must have been false in 1932, and will always have been false at all times. This latter is the view with which we agree. For the falsity of the theory in 1942 was due to the fact that it clashed with certain givens or certain percepts. In ordinary parlance we should say that it clashed with certain facts. Now those facts were also facts in 1932, only they were not then known. That they existed unperceived in 1932 is, of course, a construction. But it is a construction which has long ago been accepted as true by the human mind. Hence the issue is quite clear. When we say that a judgement is false if it disagrees with the given facts, do we mean to refer to the then known facts or to all facts known and unknown? It seems to me that the former view introduces chaos into the theory of truth. For suppose that I believe that horse X won the Derby yesterday, when in fact horse Y won it. We should surely say that my belief was false. But, if we adopt the view against which I am arguing, we shall have to say that, as my belief did not clash with any facts which were known to me, it was true. Which is absurd.

……… common sense proceeds upon a crude form of the 'correspondence' theory of truth. Our theory is also essentially a form of the correspondence theory, though it is hoped that it is less crude. Both for us and for common sense truth is tied by the facts, and does not change Proteus-like from day to day, according to our wishes, as the pragmatists would have us think.

No doubt this means that we can never be certain, in regard to complicated scientific theories, that we have reached any measure of truth. We can never be certain until we know all the facts, i.e. until we are omniscient. But I see no objection to admitting this. It does not render science hopeless or vain. For although we can never attain certainty, there is a growing probability that our theories are true the more we come to know of the facts. Moreover it must be remembered that theories are complex, i.e. they consist of a large number of judgements some of which may be true, some false. When theory A is superseded by theory B, it is not usual to find that the whole of theory A is false. We are more likely to find that a very few of the judgements of which it was composed are inconsistent with the new facts, but that most of them are still left standing as true. In this way theories A, B, and C may be regarded as increasing approximations to the truth. And lastly, theory A, though false or partly false, was useful in its time since it explained the then known facts and yielded true predictions of experience. Even in 1942, when it has been superseded, it may still be used within certain defined limits to explain and predict. This means that it has become a methodological assumption.

There is one fact regarding the nature of existential constructions which may, if its implications are not dis- cussed and cleared up, give rise to difficulties. This is the fact that such constructions are only expressible in hypothetical propositions whose antecedents contain impossible conditions. This appears so far as a strange peculiarity, a sort of eccentricity on the part of the existential construction. We have stressed it throughout, but made no attempt to explain it. The time has now come when we must endeavour to do so.

The difficulty which it seems to create is that it appears to involve the construction in a logical contradiction And since it is one of the conditions of the validity of a construction that it shall be internally self-consistent, any such admission would be fatal to the validity of all existential constructions. The difficulty will be most easily examined if we take a concrete case. We assume the existence of the unperceived table. This means 'if any one were now looking, he would perceive the table'. But by hypothesis no one is looking. The belief in the unperceived table therefore attempts to combine the hypothesis that no one is looking- with the supposition that some one is looking. This is what renders the condition which is contained in the antecedent an impossibility. This is, in fact, a logical contradiction. The point may be put otherwise by considering that since in its ultimate meaning, esse is simply percipi the hypothesis of the unperceived table amounts to believing in an unperceived percept, a non-existent existence lhe same kind of contradiction may be found in every existential construction. And it may therefore be argued with some show of plausibility that no existential construction is ever valid.

The first point to notice here is that, although every existential construction contains an apparent logical contradiction, it is always one and the same contradiction which appears in them all. The assertion of the existence of the atom means 'if. . ., then we should perceive atoms'. 1 he assertion of the existence of the invisible side of the moon means 'if we were on the other side, we should see it livery existential construction supposes an existence which we should perceive The contradiction in all cases resides in the fact that we suppose something to be perceived while at the same time asserting that it is not perceived. It arises from the attempt which we are always making to get away from the fundamental identity of esse and percipi. It is, in short, the contradiction of the unperceived percept.

This primitive contradictory assumption is a kind of original sin which the human mind committed when man first began to eat of the fruit of the tree of knowledge. It keeps breaking out afresh everywhere in knowledge, in the case of the ether or the atoms as much as in our common sense beliefs about tables and chairs. But we have at least only one contradiction to deal with in all cases, not a distinct contradiction for each existential construction.

We have thus only one problem to solve, and it does not seem difficult of solution when we come to examine it. There is in truth a contradiction involved, and the mind accepted it once and for all when it undertook the great adventure of admitting that, although esse is percipi, yet things can exist unperceived. There is only one possible way of reconciling the contradiction, and that consists in pointing out that this admission is, after all, only a supposal, a make-belief, a pretence which has been entered into for the purpose of enriching life and knowledge. The contradiction is reconciled, in fact, by pointing out that the unperceived object has not factual but only constructive existence. If it were supposed that the unperceived object has factual existence, then the contradiction would be final and insoluble. This is, in fact, the contradiction which lies at the root of all forms of the theory of representative ideas, and which has broken out perpetually in the history of philosophy in one form or another. If we persist in asserting it, we shall then either have to give up the doctrine that esse is percipi, or the doctrine that things exist unperceived. Realists follow the former course and deny to existence its essential relativity to perception. Phenomenalists, I suppose, would follow the latter alternative, and deny that anything exists unless it is actually perceived. Our theory is enabled to grasp together both sides of the dilemma and to reconcile them. The theory of constructive existence resolves the contradiction.

It is the character of knowledge as constructive which has given rise to the category of 'possibility'. Presumably every proposition asserts or denies something. Now what is asserted or denied by the proposition 'if it had rained to-day, the ground would have been wet'? It did not rain, and the ground was not wet. Yet most people would say- that the proposition is nevertheless true. What is it that is true? What is it that is asserted or denied to be true? Not any actual fact about the universe. What is asserted is a possibility. But what is the possible? By definition it is not anything actual. It is not anything that exists or is real. Is it then an absolute non-entity? And if so, how is it that it can be meaningfully asserted? Here is a flat self-contradiction which is yet admitted every day as a valid part of knowledge. The world of possibility, it seems, is neither an existence nor a non-existence. For what exists is the actual and not the merely possible. And what does not exist is nothing, and cannot be truthfully asserted about the universe. That is the contradiction involved in the notion of the possible.

The solution of the puzzle is that the contradiction involved here is the very same contradiction which we have been considering in existential constructions. It is the same 'if …, then we should perceive’. 'If it had rained, we should have perceived wet ground.' And it ceases to be a contradiction when it is recognized as a supposal, a realm set up and brought into existence by the mind for its own purposes, a realm which is not factual. It is neither existent (factual) nor non-existent (non- entity). It is constructive existence. If we believe that in asserting the possible, in asserting hypothetical propositions generally, we are asserting a factual or actual existence, then indeed we are involved in hopeless contradictions. But if we admit that the world of possibility is a world supposed or constructed by the mind, the contradiction vanishes.

This, then, is the explanation of the strange 'if clause which dogs the steps of the existential construction.

THE picture of the universe which is presented to us at the conclusion of our inquiries may be briefly sketched. The universe is fundamentally a colony of multitudes of minds. I hold back from saying that the ultimate stuff or reality of the universe is mind. For I do not know, or at least I have not inquired in this book, what is meant by 'ultimate’ reality. Inquiries of that kind belong to the sphere of transcendental philosophy, which I have here and for the moment forsworn. Moreover, in addition to minds there are givens, floating colours and sounds relations between these, mental states as themselves intuited and given. Each monadic mind possesses and dwells in its own self-enclosed world of givens. But to say that mind is the ultimate reality of the universe would imply, I think, that it is more real than the givens, that it is in some way more 'fundamental' than they are (whatever that may mean), that it is prior to them, perhaps even that it produces them. Any of these propositions may, for all I know, be true. But they do not result from anything that is asserted in this book. I have not inquired regarding them, because in my opinion they would take me beyond the empirical standpoint which I have adopted. They would take me into the sphere of transcendental metaphysics, into questions of the purpose and rationality of things, into the why of the universe.

For the same reasons I forbear to inquire whether the parallelism of private worlds, which is a fact, and which — as was noted in Chapter VII — lies at the basis of our whole theory, is evidence of a designing mind overruling the universe; or whether the universality and necessity of logical laws, the fact that they are not personal but over-personal, does not point to some deeper universal mind of which our own minds are but individualizations or manifestations. These suggestions lie outside the scope of our limited empirical investigations. And I will only say that there is nothing in any of these views which is inconsistent with the epistemology here advocated.

For us at the close of our inquiries all we can say is (1) that minds exist and (2) that givens exist and are perceived by minds. The minds and the givens are facts, brute facts. I do not know how or why they come into existence. To make any inquiry into this is no part of my undertaking. Nor do I inquire 'what minds are' or 'what givens are' or what the 'ultimate nature' of either of them is. I do not even know what the meaning of these questions is. For to ask 'what mind is' seems to imply that it can be described or defined in terms of something else which is not mind. And I have no idea what that something else could be. Either it must be some transcendental reality, in which case we leave it to transcendental philosophers. Or else it must be some other factual existent. The only other factual existents are the givens. And it does not seem a very hopeful line to suggest that minds are wholly explicable in terms of colour patches, sounds, odours, and the like. Moreover this solution would leave us still asking 'what the givens are'. If we do not accept them as ultimate facts, then they will have to be explained either in terms of a transcendental reality or in terms of the only other known existents, namely minds. And the process of explanation would in the latter case be obviously circular. So that, if I am asked 'what minds are’ or 'what givens are', I can get no further in replying than to say that minds are minds, and givens are givens, I do not know how to answer the question 'what is the ultimate nature of a red patch?' except by saying that a red patch is a red patch. For me at this empirical standpoint minds and givens are simply ultimate facts of which no further account can be given. And it is at least questionable whether to ask for a further account of them has any real meaning.

Multitudes of minds perceiving multitudes of colour patches, sounds, tactile presentations, and other givens. These are the raw material, the ultimate constituents, of the universe. These are the only factual existents. These are the only pure facts. In this arena of primitive being the givens of each mind constitute its own private universe. There are as many universes as there are minds. And each such universe is internally disconnected, full of gaps, holes, and chasms. There are gaps between the presentations of the different senses. A sight is in a different world from a sound. There are gaps in time when the mind is asleep or unconscious "and when therefore its universe simply ceases to exist. There is a gap between the table (or the colour patch which later becomes the table) which I see now and the one I saw yesterday. They are not the 'same' table and between their two existences there is a dark blank in the picture. The whole of each private world is patchy and disconnected.

Such is the picture of the 'beginning of the world', the crude material out of which the universe has been constructed. It is in itself orderly, in that it contains regularities of sequence (which later become causal laws) and the parallelism of private worlds. It is not true to say, as is sometimes said, that it is mind which introduces all order into the universe. There are the rudiments of order there at the beginning. But otherwise the world in the beginning is patchy, disconnected, unsolid, a jumble of discrete scraps of private worlds and multitudinous bits of universes. All the rest of the universe as we know it, perduring through connected time, extending through a single space, solid, permanent, continuous, and independent of mind, all this has been built up by thousands of generations of minds labouring together,

It is quite conceivable that if there are other minds with which we are not in communication they may have built up worlds totally different from ours. If there are minds on Mars, their system of knowledge may be so unlike ours that language or communication between us might be now practically impossible, even if we could overcome the distance and the physical obstacles. For on the road of knowledge, as we have 6een, there are many forks at which the human mind may choose between different paths. These different paths are alternative truths. At most of these forks the human mind has chosen one route and has left the others unexplored. How are we to know that the Martian mind, or any other in the universe (if there be any), has taken the same turns as we have? Those other minds may have built up universes in which the multitude of private worlds, rather than the singleness of a public world, is the basic feature; in which there are two disconnected spaces, visual and tactile; in which visual space has only two dimensions; in which empty visual space does not exist; in which the motion of solid visual bodies is unknown; in which what we call motion is explained as simply change of colour on a flat world; in which the notions of substance, self-identity, thinghood, solidity, permanence, have no application, or are applied quite differently from the way in which we apply them. And it must be remembered that if these strange minds have taken turnings of the road different from those taken by us, they will have had to follow them out, diverging farther and farther from our route at every step, until they may have entered fields of knowledge which we cannot imagine. Suppose for example that, instead of inventing a third spatial dimension as we did, they built their world on the basis of a flat plane in which motions were explained as merely changes of colour. Thus far we can follow their proceeding. But as a result of this all their subsequent constructions, the whole of their physical science, will have to be quite different from ours. What vast adjustments and reconstructions of our knowledge would be necessary before it could come into line with theirs?

It may be that the human race is only one group of minds; that there are many groups; and that there exist as many different systems of knowledge as there are groups of minds; and that none of these groups could now in any wise understand one another if brought into contact.

These suggestions are not put forward for the sake of idle speculation about the men in Mars, or in remoter bodies, as is the case with those newspaper descriptions of the 'marvels' of 'science’ at which the credulous are accustomed to be set a-gaping. I do not know whether there actually are any other groups of minds in the universe or not. So far as I know, there is not the slightest evidence of it. And to speculate on the point is altogether beside my purpose. My purpose is to emphasize, by means of this picture, the fact that, owing to the existence of alternative truths, other systems of knowledge than ours are possible and would be equally 'true'.

For the building up of the world by mind, as it is conceived in our philosophy, is in no way parallel to that world-construction by Mind which was a feature of such systems as those of Kant and Hegel. For them the world was built once and for all, in some single necessary way, by some vast non-human transcendental cosmic universal Mind. But in our view it has been the work of billions of individual human and perhaps pre-human minds, working ant-like through the aeons, each contributing its morsel. It has been governed, not primarily by logical necessity, but by human, and perhaps pre-human, needs. And it might have been built quite differently.

Logically speaking, each individual mind might have adopted its own system of knowledge, and your world might be quite different from mine. I might have adopted one alternative truth, you another. There are never any logical grounds which compel us to adopt one rather than the other. If there were, they would not be alternative truths. The only reasons why the human race has developed a single common system of knowledge are (1) that men's minds are similar. For example, all minds will in general prefer the simpler and easier of two possible routes. And (2) they have laboured together in common, with a common end, and each mind influencing all the others. Their guiding aim has been a common world for the sake of fellowship. If we could discover some other group of minds in some other planet, we might find their system of knowledge different from ours. But it is to be expected that they would share a single common system among themselves.