Kant on Relative Spontaneity

I argue that examining Kant’s lectures on metaphysics can help in understanding why in the Critique of Practical Reason Kant thinks that compatibilism cannot deliver a concept of transcendental freedom. The key element that the lectures can shed light on is how Kant thinks that under compatibilism certain mental states (but not all) are part of a causal chain. In his L1 metaphysics and Mrongovius metaphysics lectures Kant discusses at length the issue of external conditions that ground our maxims and our spontaneity, thus arriving at a distinction between a power of free choice (Willkür) that is intellectual and free only in some regard, and a power of free choice that is intellectual and free without qualification. The former is externally conditioned despite being an act of maxim-formation, and thus can explain why Kant in the 5:93-96 section of the second Critique believes that under compatibilism our actions are part of an external causal chain.