The Modal Argument against Materialism and Intertheoretic Identities

Abstract

In this paper I discuss, on behalf of the materialist, a consideration against the modal or conceivability argument against materialism which was first voiced in the third lecture of Naming and Necessity. This consideration is based on intertheoretic identities, statements in which both terms flanking the identity sign are theoretical. I argue that the defender of the conceivability argument has trouble to account for the appearance of contingency in those types of necessary identities. In fact, intertheoretic identities pose a formidable dilemma for the defender of the modal argument and actually force the antimaterialist to say more about the semantics of theoretical terms than is implicit in standard discussions of the argument. I myself consider several options in this regard, the upshot being, however, that none of the alternative semantics for theoretical terms available to the antimaterialist is good enough to achieve the twofold aim which her modal argument requires, namely, to account for the a posteriori necessity of identities of this sort and, at the same time, to preserve her antimaterialist argument. Finally, in the last part of the paper, I argue that my defense of materialism can withstand some worries coming from David Chalmers’ recent views on a priori scrutability.