Commentators typically take the focus of Kant’s response of Hume to be directed at the latter’s account of causation, but this chapter argues that Kant’s critique of Hume is better understood in methodological terms.On this interpretation, Kant sees Hume as raising a ‘demarcation’ challenge’ that asks how we can distinguish between the proper deployment of reason in the natural sciences and its illegitimate use in dogmatic metaphysics – but, by Kant’s lights, Hume’s failure to recognize the ‘hylomorphic’ nature of our cognitive faculties prevents him from meeting the challenge he presents.