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318 Professor Watson shows, as Green and Jevons had already shown, that mathematical truth is not reached by induction. That the propositions of geometry and algebra are necessary, however, is another matter, and for my own part I remain unconvinced after reading Professor Watson's argument, which concludes with these words: "Viewed as expressing certain unchangeable relations which are presupposed in all our knowledge of real things, mathematics is not a hypothetical but a necessary science" (p. 85). Mill's theory of Induction is admirably discussed in Chapter V, the result of which is to show that a cause is not an invariable antecedent, but an unchangeable fact, and the effect is the same thing regarded from another point of view.

Chapters VI and VII deal with the metaphysical (and ethical) aspects of Darwinian Biology. As might have been expected from so careful a student as Professor Watson, the exposition is just and lucid. Following the lines laid down by Professor Huxley in his well-known chapter in Darwin's Life and Letters—a view which had previously been presented by other writers—Professor Watson shows that, while Darwinism overthrows the old conception of design as formulated by Paley, it is not inconsistent with such a philosophical conception of teleology—immanent purpose—as that propounded by Kant. In the harmony between the organism and its environment, whereby existence is rendered possible; in the impulses to self-maintenance and race-maintenance, whereby a struggle for life is necessitated; and above all, in the tendency to organization, which is the characteristic of living beings; we have, according to Professor Watson, distinct indications of the presence of intention in the universe. "In life," as Kant said, "the idea of purpose first clearly presents itself" (p. 122). Coming to man, it is recognized that natural selection, if the letter is emphasized, tends to abolish the distinction between intelligence and unintelligence. But in that event, Professor Watson argues acutely that neither knowledge nor voluntary action would be possible. Chapter VIII is entitled the "Philosophy of Mind." Whoever wants to know what philosophical objections may be brought against Spencer's theory of knowing and of being, and what may be said, on the other hand, in defense of that Absolute Idealism which holds that the universe is at heart self-conscious intelligence, should read this chapter, which, though the longest in the book, covers only 45 pages. It is too pregnant for any summary. The author dashes off with the touch of a master the figures of Scientific Evolutionism and