Abstract

Barbara Vetter has argued that the notion of a metaphysical possibility functions like a natural-kind concept that picks out whatever kind is instantiated by the large majority of paradigmatic examples. Vetter holds that proponents of such a view can reject appeals to intuition and a priori reasoning as ways of supporting claims about the extension of metaphysical possibility, and that the attractiveness of a natural-kind account is consequently undiminished by intuitive counterexamples. This paper argues that that is far from obvious. It may be true on a natural kind view that the claim that it is metaphysically possible that p can be established only on the basis of empirical evidence about which kind is instantiated by most paradigm examples and what the members of this kind are. However, that leaves open the possibility that intuition and a priori reasoning can be used to evaluate conditional claims of the following form: If the kind instantiated by most paradigm examples includes (fails to include) X, then it is possible (not possible) that p. If intuition and a priori considerations can be used in this manner, then they are relevant to the assessment of the natural-kind view. Keywords: modality, natural kinds, the a priori, intuition, potentiality.