Abstract
This chapter argues that the ordinary cognitive capacity to handle counterfactual conditionals carries with it the cognitive capacity to handle metaphysical modality. It aims to illustrate with examples our cognitive use of counterfactual conditionals, and sketches an epistemology for such conditionals. The chapter explains how they subsume metaphysical modality, and assesses the consequences for the distinction between a priori and a posteriori knowledge. It discusses the relation between metaphysical possibility and the restricted kinds of possibility that seem more relevant to ordinary life. Philosophers’ ascriptions of metaphysical modality are far more deeply rooted in our ordinary cognitive practices than most skeptics about it realize. Many philosophers are more confident in their judgments about more or less realistic thought experiments in epistemology and moral philosophy than about more radically strange ones in metaphysics. Philosophical controversy will naturally make the unclear cases salient.