A science for gods, a science for humans: Kant on teleological speculations in natural history

Kant's forthright rejection of rampant, ungrounded speculations in natural science, including in natural history, is well known. For instance, he dismisses the wild, unwarranted developmental histories of other early natural historians, such as Buffon and Herder, as “daring adventure[s] of reason.” However, as I show in this paper, Kant himself made use of teleological speculations in natural history, particularly in his three essays on race. I argue that, for Kant, speculations about nature's purposes are necessary to explain and to buttress the unification of organisms in real species, despite observable and heritable variations among members of these species. Without hypothesizing about nature's intentions, a mechanical, efficient-causal account of nature cannot appropriately ground the unity of species. Hence, I depict Kant's account of natural history as threading a needle between merely mechanical accounts of nature – which are incapable of achieving the goals of the science – and freewheeling, conjectural narratives about the origin and development of the Earth, life, and humanity. In the end, I conclude that my account reveals a substantive role for the faculty of reason in natural history, which dovetails with recent work on Kant's views on the non-physical sciences.