In this article I argue that Kant considered Hume’s account of causality in the Enquiry to be primarily relevant because it undermines proofs for the existence of God and, moreover, that this interpretation is plausible and text-based. What the Prolegomena calls ‘Hume’s problem’ is, I claim, the more general question as to whether metaphysics can achieve synthetic a priori knowledge of objects at all. Whereas Hume denied this possibility, I show how the solution Kant develops in the Critique of Pure Reason is in agreement with Hume’s critique of dogmatic metaphysics, but salvages the synthetic a priori principles he takes to be constitutive of empirical cognition.