Kant on Determinism and the Categorical Imperative

I provide a sympathetic reconstruction of Kant's motivation for endorsing incompatibilism about human freedom. On my interpretation, Kant holds that if all the determining grounds of our actions were subject to natural necessity, we would never be free to respect or defy laws of practical reason, and for Kant such freedom is a condition for the possibility that our actions are governed by categorical imperatives. I argue that his view rests on a gripping construal of the rational imperfection that afflicts the human will.