Page:Philosophical Review Volume 15.djvu/152

134 all, the real things, and the mental states are dependent on them. The real causes are the brain operations. Hence knowledge of brain action is real scientific knowledge. It is the business of the scientific thinker to explain these states of consciousness by referring them to their causes just as he explains sound and light. Colors and tones are the effects of ether and air waves respectively, ether and air waves are not the effects of colors and tones. Similarly, states of consciousness are explained by, but do not explain, brain states. The ideal of the physiologist must therefore be what Exner conceives it to be: "I regard it as my task," he declares, "to explain the most important psychic phenomena by degrees in the excitations of nerves and nerve centers, hence to reduce everything in consciousness that appears to us as a manifoldness to quantitative relations and different connections in otherwise essentially homogeneous nerves and centers." This view represents the climax of the mechanical theory of the world, which, after having conquered the inorganic realm and laying claim to the organic sphere, now proposes to take possession of the mind as the natural appendage of the latter.

Disguise it as we may, however, this argument rests upon the questionable metaphysics of materialism. If it were true and the ideal held up were realized, psychology would in a certain sense play second fiddle to physiology. So would logic and ethics, political and social science, history and philology; all would find their ultimate explanation in a mechanics of the brain. Physiology in turn would be reduced to physics; physics would be the mother science, and we should be back again in metaphysics.

And still there would be room for psychology. The psychologist would keep right on studying the so-called effects of brain action, the states of consciousness; he would seek to analyze and describe them and discover the order that is in them. However complete our knowledge of the brain motions might be, this would not tell the whole story; indeed, it would not touch the real problem of psychology at all. Only in case there were no states of consciousness, or if they could not be reduced to any form of law, if there were neither rhyme nor reason in them,