Cosmology (from the Greek κόσμος, kosmos "world" and -λογία, -logia "study of"), is the study of the origin, evolution, the basic and the large-scale structures, and ultimate fate of the universe.
The term cosmology stands for a group of related inquiries, in the attempt to gain knowledge of the universe as a whole. Two main subgroups are physical (scientific) cosmology and rational (metaphysical) cosmology.
Physical Cosmology applies the scientific methods with which the observational astronomers and the theoretical physicists are involved in the factual study of the whole and the parts of the universe, as well as the governing laws of physics.
Rational Cosmology reflects on the contemporary sciences and speculates on the origin, fundamental structure, and space-time relationships of the physical universe, in its totality. Its problems are the nature of material existence, the concept of uniformity of nature and the laws of physics, the concept of space and time, etc.
In cosmology, we discuss the questions connected with such categories as those of uniform spatial extension, uniform obedience to general law, and the constitution of a whole which is an aggregate of parts.
Rational Cosmology would be useless if conceived of as a substitute for the experimental study of the experimental science. Rational Cosmology is essentially a sub-division of Metaphysics, and for that very reason is incapable of adding a single fact to the sum of our knowledge. However, Metaphysics has a real value, but a value of a different kind. It is concerned not with accumulation of facts, but with the interpretation of previously ascertained facts, looked at broadly and as a whole. For example, the whole process and the justification of scientific investigation assume uniformity of nature and that the facts with which the hypothesis concerned conform to general laws. (Taylor 47)
The work of the Rational Cosmology only begins where that of the experimental sciences leaves off. Its data are not particular facts, as directly amasses by experiment and observation, but the hypotheses used by experimental science for the description of those facts. And it examines these hypotheses, not with the purpose of modifying their structure so as to include new facts, but purely for the purpose of estimating their value in giving us knowledge of ultimate reality. (Taylor 192-193)
The conception of all existence is divided into two great orders, the physical (Materialism) and the psychical (Idealism).
Material Cosmology is the critical examination of the special characteristics of the physical order.
a) Physical existence is purely material and non-mental
b) The physical order is made up of events which conform rigidly to certain universal laws of physics. In other words, the sequence of events in the physical order is mechanically determined by the principle of Causality.
c) Every element of the physical order fills a position in space and in time. Hence any metaphysical problems about the nature of space and time are bound to affect our view of the nature of the physical order.
d) The physical order, as thus finally constituted by the introduction of the imperceptible mind or soul, now comprises all sensible existence, linked together by the principle of Causality. With the notion of a continuous evolution as scientific fact, we may ultimately define the physical order as a body of events occupying position in time and space, conforming to general laws with rigid uniformity, and exhibiting continuous evolution.
From these general characteristics of the physical order, as conceived by current science and popular though, arise the fundamental problems of Cosmology. We have to discuss:
1. The real nature of material existence, i.e. the ultimate significance of the two orders, the physical (Materialism) and the psychical (Idealism), and the possibility of reducing them to one.
2. The justification for the distinction between mechanical and teleological processes, and for the conception of the physical order as rigidly conformable to uniform law.
3. The conception of space and time, and their bearing on the degree of reality to be ascribed to the physical order.
4. The philosophical implications of the application of the notion of evolution to the events of the physical order.
5. The problem of the real position of descriptive physical science as a whole in its relation to the rest of human knowledge.
Reality is always a concrete unity of experience in which the two distinguishable aspects of a conscious fact, its existence and its content, the that and the what, though distinguishable, are inseparable. (Taylor 55)
We may now see that what is thus illustrated by the case of artistic perception holds good to all advance in the understanding of reality. (Taylor 33)
Every experience appears to be implicitly complex in respect of its content.
Its aspect of content appears never to be absolutely simple, but always to contain a plurality of aspects, which, as directly felt, are not distinct, but are distinguishable upon reflection. For instance, in even the most rudimentary experience there would appear to be some subjective pleasure or pain that accompany the objective quality of a sensation. (Taylor 33-34)