Kant criticizes the so-called ‘preformation’ hypothesis – a nativist account of the origin of the categories – at the end of the B-Deduction on the ground that it entails scepticism. I examine the historical context of Kant's criticism, and identify the targets as both Crusius and Leibniz. There are two claims argued for in this paper: first, that attending to the context of the opposition to certain forms of nativism affords a way of understanding Kant's commitment to the so-called ‘discursivity thesis’, by contrasting the possession conditions for the categories with those for innate ideas; secondly, it provides an insight with regard to Kant's understanding of the dialectic with scepticism. Kant's claim is that a certain explanatory lacuna that attaches to Humean empiricism can be seen to apply equally to any nativist theory. The lacuna concerns the explanation of the modal purport of a priori necessity, i.e. how it is that our consciousness can even distinguish contents that are represented as necessary features of objects.
