In his final notebooks, published as On Certainty, Wittgenstein offers a distinctive conception of the nature of reasons. Central to this conception is the idea that at the heart of our rational practices are essentially arational commitments. This proposal marks a powerful challenge to the standard picture of the structure of reasons. In particular, it has been thought that this account might offer us a resolution of the traditional scepticism/anti-scepticism debate. It is argued, however, that some standard ways of filling out the details of this proposal ultimately lead to an epistemology which is highly problematic. The goal here is to present a more compelling version of Wittgenstein's account of the structure of reasons which can evade these difficulties.