Counterfactuals and the Epistemology of Modality

The paper provides an explanation of our knowledge of metaphysical modality, or modal knowledge, from our ability to evaluate counterfactual conditionals. The latter ability lends itself to an evolutionary explanation since it enables us to learn from mistakes. Different logical principles linking counterfactuals to metaphysical modality can be employed to extend this explanation to the epistemology of modality. While the epistemological use of some of these principles is either philosophically implausible or empirically inadequate, the equivalence of ‘Necessarily p’ with ‘For all q, if q were the case, p would be the case’ is a suitable starting-point for an explanation of modal knowledge