While all of Hume's readers agree that he is a sceptic – he calls himself a “true” sceptic in the “Conclusion” to Book I of the Treatise and a “mitigated” sceptic in the final Section of the first Enquiry – there is almost no agreement on what this kind of scepticism amounts to. I will limit my contribution to this controversy here to an examination of Hume's first engagement with scepticism, his exploration in “Of scepticism with regard to reason” (T.I.iv. 1; hereafter SwR) of the argument that we should not accept the verdicts of our reasoning; I reconstruct this sceptical argument in Section 1. What Hume wants us to learn from this exploration has also been the focus of much debate amongst his recent readers. There are three main interpretive positions, none of which to me seems satisfactory, but each of which I will suggest contains a germ of truth.

First, some have suggested that Hume's argument against our believing the verdicts of our reasoning is meant to be entirely ad hominem. For, after he has presented it, he says: