science by excluding from it all metaphysical assumption whatsoever. And since "all attempts to explain our phenomenally given thoughts" (that is, the whole sphere of descriptive psychology) "as products of deeper-lying entities are metaphysical" (p. vi), the explanatory office of the science cannot legitimately make use of even the postulate of a "soul," or — what is more surprising still — of any " Elementary Units of Consciousness." For, according to the author, "metaphysics fragmentary, irresponsible, and half-awake, and unconscious that she is metaphysical, spoils two good things when she injects herself into a natural science."
Now as to the explanatory value of the metaphysical postulate of a soul, I reserve for later pages of this article my contention with Professor James. For I differ decidedly from his opinion — at least as expressed in this passage. However, I take courage and hope for a nearer approach to a common view, upon discovering elsewhere the following utterance: "I confess, therefore, that to posit a soul influenced in some mysterious way" (why more "mysterious" than all so-called influence?) "by the brain-states and responding to them by conscious affections of its own, seems to me the line of least logical resistance, so far as we yet have attained" (I, p. 181). But is not "the line of least logical resistance" the line of most logical momentum, or — in other words — the line that marks out the best explanatory postulate of a metaphysical kind?
One can scarcely find fault, however, with Professor James for excessive parsimony in the matter of metaphysics, considering that his intention, avowed and repeated, is to treat of psychology purely as a natural science. On the contrary, the entire first half of the first volume seems to me far too metaphysical for the preliminaries of a scientific treatise; while a vast amount of conjectural metaphysics of physics is woven into the very texture of both volumes. Indeed, on the page of the Preface already referred to (p. vi) we are told that psychology assumes as one of its data, "a physical world in time and space with which they (i.e. the phenomena of psychology, the thoughts and feelings of individual minds) coexist, and which they know"
