Physical and metaphysical modality

Abstract

Philosophers widely if not universally agree that physical and metaphysical modality are to be distinguished. Metaphysical modality is supposed to be strictly broader, as witness what seems to many to be the obvious truth that the laws of nature – and so, the merely physical necessities – could have been otherwise, in an appropriately “metaphysical” sense of “could have been”. Different particles frequently exhibit different values for mass. But it’s an unbroken regularity that no particle by itself ever exhibits, at the same time, two distinct values for mass. One might think that explanation is important, and even that certain key metaphysical notions are needed to say what explanation is (e.g., the notion of a causal power or capacity), but revolt at the “fundamentalist” claim that all relations of explanatory dependence are grounded in constraints imposed by the most basic ingredients of the SCARF.