On this Kant remarks as follows:
These ideas will not, indeed, cause the investigator of nature to shrink back from before them with a shudder, as from before a monstrosity
(for there are many who have played with them for a time, though only to give them up as unprofitable). But the investigator will
be frightened away from them upon a serious scrutiny, by a fear lest he be lured by them from the fertile fields of natural science to wander in the wilderness of metaphysics. And for my part I confess to a not unmanly terror in the presence of anything which sets the reason loose from its first and fundamental principles and permits it to rove in the boundless realms of imagination.
Kant's alarm, it is evident, was aroused by all three of the hypotheses which he ascribed to Forster. But he particularly disapproved of any attempt to inquire into the origin, the laws of genesis, of organisms in general, or of the original "stock" from which any species is descended. Such inquiries "lie beyond the province of any possible physical science." For science is competent to discover only relations of efficient causation; but organisms, being material systems "in which every part is at once cause and effect of every other part," admit only of "a teleological, not at all of a physico-mechanical, mode of explanation."
6. The "Kritik of Judgment."—The principal source of the belief that Kant was an evolutionist in biology is a celebrated passage in the "Kritik of Judgment" (1790), § 80. This passage is, unfortunately, usually quoted with its most important part—an appended foot-note—omitted. That Kant's true position may clearly appear (in so far as a position which is involved in a scheme of elaborate self-contradictions can ever be clear), it is necessary to cite the text here nearly in full:
It is praiseworthy to go through the great creation of organized natures with the aid of comparative anatomy, in order to see whether there may not be in it something resembling a system, even in the principle of generation of such beings. For otherwise. . . we are obliged to give up in discouragement all pretension to natural insight in this field. The agreement of so many species of animals in a certain common plan which appears to underlie not only their skeletal structure but also the arrangement of their other parts—so that, upon the basis of an original outline of wonderful simplicity a great variety of species could be produced merely by the shortening of one member and the lengthening of another, the diminution of this part and the elaboration of that—all this gives our minds a ray, though a feeble ray, of hope that something may here really be done with the principle of the mechanism of nature—apart from which there can be no natural science as such. This similarity of forms—so great that, amidst all their diversity, they seem to have been produced according to a common original type—gives force to the surmise of an actual relationship between them, by virtue of their generation by one primal mother (Urmutter)—through the gradual approximation of one animal species to another, from that in which the principle of purposiveness seems best established, i. e., man,
Schriften," HI., p. 335, Forster emphatically asserts the immutability of "the principal features of the primitive form (Urbild) of every species."
- ↑ Kant refers to a passage of Forster's in which these expressions are jestingly used. But, as it happens, they were originally Kant's own expressions, occurring in the review of Herder's "Ideen," already cited.