genetic and the descriptive equivalent merely to the distinction between past and present. It need hardly be said that genetic inquiries in science are not necessarily purely historical or archeological inquiries, since phenomena of genesis may be recurrent phenomena, taking place in accordance with the same laws in past or present. But, though he blurred the idea somewhat, it remains true that, in his contrast between two types of scientific research, Kant exhibited his inclination to what, in the vaguer sense, may properly be described as an evolutionary habit of mind. It still remains, however, to determine just how far this carried him, when he came to the consideration of definite problems.
His problem of predilection, as I have said, was that of the nature of a "race," the relations of different races, and the causes of their diversity in physical characters. And this made necessary, at the very outset, a consideration of the nature of a "species." Here, once more, Kant follows Buffon: "Animals, however different they may be in form, belong to the same physical species if, when mated with one another, they produce fertile offspring."
This Buffonian rule gives a definition of natural species as such (die Definition einer Naturgattung der Tiere überhaupt), in contrast with all artificial species (Schulgattungen). The artificial classification deals with classes, which are grouped together upon the basis of similarity, the natural classification deals with lines of descent, grouping animals according to blood-kinship. The one provides an artificial scheme to aid the memory, the other a natural system for the understanding. The purpose of the former is merely to bring animals under labels, that of the latter is to bring them under laws.
These references to Naturgattungen, determined by the criterion of fertility of offspring, are themselves hardly in the language of transformism. Yet one who employed such language might still regard these "true species" as eventual results of divergent descent from common ancestors. But when we examine Kant's way of further defining these species, we find that his notion of them expressly precludes the possibility of any transformation of one into another through descent. By the Buffonian test, he says:
All human beings belong to one and the same natural species, since in mating they always beget fertile offspring, however dissimilar the parents may be in appearance. For this unity of natural species there can be but one natural cause, viz., that all men belong to a single stock (Stamm), from which they have originated or at least could have originated. In the former case [i. e., of actual descent from common ancestors], they belong not only to one and the Bame species, but also to one family; in the latter case they would be similar to one another but not related, and it would be necessary to assume a number of separate local creations: an opinion which multiplies causes beyond necessity.[1]
- ↑ The same ideas are perhaps still more clearly expressed in the article "On the Use of Teleological Principles in Philosophy," 1788: "There could be no more certain test of diversity of stock (des ursprünglichen Stammes) than the inability of two different hereditary branches of mankind to engender fertile
