Abstract

According to Williamson, our knowledge of metaphysical necessities and possibilities is just a “special case” of our knowledge of counterfactual conditionals. This subsumption of modal under counterfactual thinking mainly serves a methodological role: to sign the end of “philosophical exceptionalism” in modal epistemology, namely the view that our knowledge of metaphysical modalities is obtained by means of a special, dedicated, possibly a priori, capacity. In this paper, I show that a counterfactual approach to modal epistemology is structurally similar to more traditional “conceivability-based” approaches. On this basis, I then show that the counterfactual approach suffers some of the same problems and I conclude that it is still based on a quite exceptional capacity to determine the truth of modal metaphysical claims. Given that, for Williamson, the epistemology of thought experiments should also be subsumed under the counterfactual approach, the problem I raise in this paper has consequences for his approach to thought experiments.