This article examines Kant’s treatment of the design argument for the existence of God, or physicotheology. It criticizes the interpretation that, for Kant, the assumption of intelligent design satisfies an internal demand of inquiry. It argues that Kant’s positive appraisal of physicotheology is instead better understood in terms of its polemical utility for rebutting objections to practical belief in God upon which Kant’s ethicotheological argument rests, and thus as an instrument in the transition from theoretical to practical philosophy. Kantian physicotheology plays this role (a) by criticizing alternative speculative accounts of the ground of nature, and (b) by analogizing from the structure of finite rational agency in order to represent more clearly the action of an ideal agent.