Manfred Kupffer

This paper is devoted to the search for an argument for the existence of a posteriori identities. I will try to improve on existing predecessors and defend the result against Scott Soames' critique in his recent book "Beyond Rigidity". First I will inspect Kripke's original argument as well as Soames' reconstruction. This reconstruction, while closely related, is shown to differ from Kripke's original in important respects. I will then ask whether either the original or Soames reconstruction may be considered as satisfactory arguments for the existence of aposteriori identities. I will show that this is not the case. These arguments use objectionable notions of apriority, but this problem can be remedied. The result will still be open to Soames main criticism against Kripkean arguments, namely that they are committed to principles of disquotation, principles of a kind that Kripke himself has later shown to be objectionable. Therefore, I will also sketch a defense of principles of disquotation.

David Lewis proposed to deal with the semantics of sentences that state what is possible for an individual in terms of possible individuals that are in ways the first individual might have been, so called counterparts of the individual. In this book, I defend counterpart semantics as an approach to the semantics of modality and natural language semantics in particular. Counterpart semantics has a rival, the standard Kripkean semantics that deals with the same sentences in terms of an accessibility relation between possible worlds. While counterpart semantics appears to be more flexible and carries less metaphysical presuppositions (it does not presuppose that I myself exist in various possible worlds, e.g.), Kripkean semantics has some advantages of its own. Most importantly, it incorporates the core assumptions of what may be called standard possible-worlds semantics; i.e. the core assumptions of the most successful framework within linguistic semantics. Counterpart semantics, on the other hand, does not conform to these assumptions, or so I will argue. In this book I opt for a synthesis of these two approaches that allows to combine their advantages. In Chap.1 I introduce the basic idea of counterpart semantics. I defend counterparts against the charge, made by Kripke, that counterparts are irrelevant for the analysis of modality. In Chap. 2 I present the classical version of counterpart semantics, i.e. David Lewis's translation of the language of quantified modal logic into counterpart theory. I discuss some well-known problems and opt for a revision of that translation that is able to solve the problems. Lewis's translation indirectly defines semantical values for expressions of quantified modal logic. In Chap.3 I evaluate counterpart semantics with respect to basic features of possible-worlds semantics. I conclude that the semantical values indirectly assigned to sentences by Lewis's translation are not sets of possible worlds, and that they do not meet certain intuitive demands on notions of meaning and content. (The revisions proposed in Chap.2 do not change this.) In Chap.4 I discuss various versions of a combination of counterpart semantics with Kripkean semantics found in the literature. But I conclude that here, the benefits of the latter are achieved by forfeiting the advantages of the former. Chap.5 finally contains my own proposal how to combine the two approaches in a more satisfactory way. The core semantical notion is truth according to a maximal complete representation, where representations now play the role of worlds. It is an important feature of the counterpart relation that it is qualitative, i.e. a relation in which things stand in virtue how they are. In Chap.1 I point out why it is qualitative, and why it ought to be. In Chap.6 I show how to make the notion of a qualitative property or relation precise. Finally, in Chap.7 I show how to extend this and related notions to predicates and propositions. For counterpart semantics to work at all we have to assume that everything that can be said at all can in principle be expressed in a language with qualitative predicates only (and perhaps, additionally, names, treated directly referentially). In Chap.7 I show how this assumption allows to maintain that the representations of our semantics deserve their name.