as with Berkeley, so with the others; for example, he never quite gets hold of Kant's phenomenalism. It is Hume, however, who, through that analysis of causation which made him famous and which constitutes the basis for the logic of induction, is of dominant influence on Professor Brooks. The results which Hume obtained are, as is generally well known: (1) that, tracing our concept of cause back to its origin in perception, there is given here only sequential and factual but never necessary connection; (2) that, however, from the experience of frequently repeated specific sequences, a belief in their regular and uniform and even necessary occurrence is generated, or, more generally, that a belief in a universal, necessary order is formed. (3) The belief is justified and is of value practically, but nevertheless, that there is a universal and necessary regularity or order is a pure assumption, or (Mill) it is itself that generalization, by induction from a limited number of cases, which lies at the basis of all specific inductions and gives the "inductive syllogism." All this means that, although a purely deductive theoretical mechanics as = "the geometry of motion" is possible and as such may be identified with determinism, this can be applied to nature only by finding the numerical values for certain functions or properties or qualities experimentally and factually. It means, accordingly, that in just this respect nature is not deductive, is not determined, and that the view that it is "order" is an assumption neither proved nor provable. This does not mean that the same cause under the same conditions does not bring about the same effect; it may, or it may not, but that this is the case is simply the same assumption over again.
It is on the basis of this criticism and analysis of causation, of "order," etc., that Professor Brooks discusses very interestingly such topics as the "Philosophy of Evolution," "Paley and the Argument from Contrivance," "The Mechanism of Nature," etc. If mechanism is to be equated with determinism and "order"—and that is all that it really means to the majority of biologists as well as to the majority of people—then it also is, like them, as above explained, only a pure assumption. But the possibilities or consequences resulting from this are interesting and important. For, with it unproved that there is that kind of continuity and causation and "order" and determinism which would make a purely deductive knowledge possible, there is the logically valid opportunity for spontaneity and genuine discontinuous origin and freedom and teleology and purpose; and yet all of these are quite consistent with that other view of "order," etc., which means that, when specific instances of these have once been discovered by induction, the presumption and the probability is that under the same conditions they will recur. But this simply means that there is a genuine evolution and advance which is at once compatible with mechanism in the above
