But psychology as a science, devoid of all postulating of " deeper-lying entities," does nothing of the kind. It assumes only the phenomena — the thoughts and feelings as actually known, and the possibility of ascertaining uniform relations among them. Any departure from this position is a resort to metaphysics; for it necessarily involves an appeal to "deeper-lying entities." But the entity called mind lies no deeper than the entity called brain; the postulated being which is to serve as the subject of thoughts and feelings, and so to explain them, is no more "cantankerously" or dangerously metaphysical than the being which is to serve as the subject of conjectural "explosions," "central adjustments," "overlappings " of processes, etc.
Of course, that particular portion of the physical world, in time and space coexistent with thoughts and feelings and known by them, which Professor James especially needs as datum for his science of psychology, is the human cerebrum. For, according to his conception of this science, no other "conditions" but the processes accomplished in this cerebrum, "explain" the existence of thoughts and feelings. Accordingly, the cerebrum is sometimes spoken of as though it "throws off," as a sort of total epi-phenomenon incapable of being analyzed into psychic factors or explained by reference to antecedent psychic conditions, each state of consciousness. With our author, psychology as a natural science, without metaphysics, is wholly cerebral psychology. "A blank unmediated correspondence, term for term, of the succession of states of consciousness with the succession of total brain-processes" — this is the last word of a scientific psychology, that will be clear and avoid all unsafe metaphysical hypotheses (I, p. 182).
We now have Professor James' conception of the explanatory work of psychology limited to its narrowest terms. Let it be noted that this conception excludes, as explanatory science, not only all introspective psychology, as such, but also almost the entire domain of what is customarily known as physiological psychology. All of the immense labors of Weber and Fechner, and of their pupils, in the effort to establish the law which goes by their great names, all of the most admirable treatises, like
