II. EVOLUTION IN PHILOSOPHY (cont.)
Modern Doctrine of Evolution.We now approach the period in which the modern doctrine of evolution in its narrow sense has originated. This doctrine is essentially a product of scientific research and speculation. It is a necessary outcome of the rapid advance of the physical sciences. Its final philosophic form cannot yet be said to be fixed. It may be defined as a natural history of the cosmos including organic beings, expressed in physical terms as a mechanical process. In this record the cosmic system appears as a natural product of elementary matter and its laws. The various grades of life on our planet are the natural consequence of certain physical processes involved in the gradual transformations of the earth. Conscious life is viewed as conditioned by physical (organic and more especially nervous) processes, and as evolving itself in close correlation with organic evolution. Finally, human development, as exhibited in historical and prehistorical records, is regarded as the highest and most complex result of organic and physical evolution. This modern doctrine of evolution is but an expansion and completion of those physical theories which opened the history of speculation. It differs from them in being grounded on exact and verified research. As such moreover, it is a much more limited theory of evolution than the ancient. It does not concern itself (as yet at least) about the question of the infinitude of worlds in space and in time. It is content to explain the origin and course of development of the world, the solar, or, at most, the sidereal system which falls under our own observation. It would be difficult to say that branches of science had done most towards the establishment of this doctrine. We must content ourselves by referring to the progress of physical (including chemical) theory, which has led to the great generalization of the conservation of energy ; to the discovery of the fundamental chemical identity of the matter of our planet and of other celestial bodies, and of the chemical relations of organic and inorganic bodies ; to the advance of astronomical speculation respecting the origin of the solar system, &c. ; to the growth of the new science of geology which has necessitated the conception of vast and unimaginable periods of time in the past history of our globe, and to the rapid march of the biological sciences which has made us familiar with the simplest types and elements of organism ; finally, to the recent development of the science of anthropology (including comparative psychology, philology, &c.), and to branches of historical study.