Abstract

In 'Four-Dimensional Objects' Peter van Inwagen gives two arguments for the claim that proponents of four-dimensionalism have to be counterpart theorists. Recently Jack Copeland, Heather Dyke, and Diane Proudfoot, echoing in part points made by Mark Heller in this journal in 1993, have sought to rebut one of van Inwagen's arguments. In this paper I shall criticize their discussion and by implication certain points made by Heller. In so doing I shall also rebut a possible objection to van Inwagen's second argument. While I shall conclude that Copeland et al . fail to make their case, I nevertheless argue that van Inwagen's argument can be resisted, provided that the four-dimensionalist is willing to adopt a certain conception of transworld identity. Moreover, I shall argue that to the extent that van Inwagen's paper highlights something problematic for four-dimensionalism in this particular conception of transworld identity, the paper highlights something equally problematic for three-dimensionalism.