Reply to Vetter

Click to increase image sizeClick to decrease image size

Notes

1. Several authors have misinterpreted the account in Williamson (2007) as moving from the logical equivalences between claims of metaphysical modality and claims involving counterfactual conditionals to the idea that we first know the latter and then use the logical equivalence to come to know the former. That was never part of my view. Rather, the idea was that we can use a similar cognitive process in coming to know either side of the equivalence, and that an economical and plausible hypothesis is that indeed we do so. As emphasized in that book, since each claim of metaphysical modality is logically equivalent to several different counterfactual formulations (which are therefore logically equivalent to each other), and the latter will each be known by slightly different cognitive processes, only approximate similarity can in general be postulated. Indeed, each particular counterfactual formulation may be known in various different ways. This is just what one would expect on the counterfactual approach. The main point is that if one has what it takes to evaluate counterfactual conditionals, one already has what it takes to evaluate claims of metaphysical modality, so there is no need to postulate an additional faculty just to explain our ability to do the latter.

2. Vetter says of Williamson (2016a): ‘there he appears to think of can statements along the lines of a version of the conditional analysis of ability ascriptions’. But I agree with Vetter in rejecting that analysis. In the relevant passages, I argue that through a single imaginative exercise one sometimes learns both that one can do something and that if one were to try to do it one would succeed; I do not claim that the two items of knowledge are equivalent to each other.