Scepticism is the second approach to metaphysics that Kant considered an alternative to his ‘critical’ investigation. It is David Hume who plays the role of the paradigmatic representative of this viewpoint. I begin by analyzing three different readings of Kant’s understanding of Hume’s scepticism about causality. Hume’s scepticism is seen as posing a challenge to natural science and ordinary knowledge, as a problem that puts into question the possibility of general metaphysics, or as a ‘dialectical’ form of scepticism primarily directed against special metaphysics. I suggest that the first reading is implausible. I argue that the second and third readings are compatible once one distinguishes between the perspectives of transcendental philosophy and the critique of pure reason, respectively. Finally, I show that one objection that has been raised against the third reading can be silenced if we interpret Kant’s reading of Hume from the standpoint of his history of pure reason.