Lewis and the Poisoned Pawn

Abstract

Lewisian modal realism is infamous for explaining the objectivity of modal discourse in terms of concrete possible worlds. Many have developed alternative theories which seek to explain the objectivity of modal discourse without concrete possible worlds. One such alternative, due to Fabrizio Mondadori and Adam Morton, attempts to ground modal discourse in actual, physical fact. Shockingly, Lewis seems to have claimed that their view is consistent with his own. I argue that the two views are consistent, from Lewis’s perspective. The result of the project is twofold. First, we see that in Lewisian realism intrinsic features of the actual world are a necessary component (i) for making modal propositions true in the actual world and (ii) for causally explaining how modal events would occur, if they did. Second, this insight motivates a rejection of the classic ‘Humphrey objection’ to counterpart theory, and ameliorates the worry that Lewis’ possible worlds somehow “change the subject”.