Iteration for Metaphysical Necessity

Abstract

This is the second of two chapters exploring the option of resolving various Tolerance Puzzles by denying Iteration, the claim that whatever is possibly possible is possible. This chapter argues for Iteration for metaphysical possibility, based on the premise that metaphysical possibility is the broadest form of possibility. Some reject this on the grounds that, for example, it is logically possible (although metaphysically impossible) that Hesperus is distinct from Phosphorus. We show that those who accept this premise should reject the form of existential generalization required to derive the conclusion that there is a form of possibility that attaches to the proposition that Hesperus is distinct from Phosphorus. We show how under certain attractive assumptions about the grain of higher-order reality one can show that there is a broadest form of possibility, and indeed define it in purely logical terms.