 One helpful way to understand acting “under the Idea of freedom” is by analogy with acting “under the Idea” that there are purposes in nature: Although there is, according to Kant, no rational basis for the belief that the natural world is (or is not) arranged according to some purpose by a Designer, the actual practices of science often require looking for the purpose of this or that chemical, organ, creature, environment, and so on. Thus, one engages in these natural sciences by searching for purposes in nature. Yet when an evolutionary biologist, for instance, looks for the purpose of some organ in some creature, she does not after all thereby believe that the creature was designed that way, for instance, by a Deity. Nor is she having some feeling of “designedness” in the creature. To say that she “acts under the Idea of” design is to say something about the practice of biology: Practicing biology involves searching for the purposes of the parts of living organisms. In much the same way, although there is no rational justification for the belief that our wills are (or are not) free, the actual practice of practical deliberation and decision consists of a search for the right causal chain of which to be the origin — consists, that is, seeking to be the first causes of things, wholly and completely through the exercise of one’s own will.