Relational Modality

Abstract

Saul Kripke’s thesis that ordinary proper names are rigid designators is supported by widely shared intuitions about the occurrence of names in ordinary modal contexts. By those intuitions names are scopeless with respect to the modal expressions. That is, sentences in a pair like

• (a) Aristotle might have been fond of dogs

• (b) Concerning Aristotle, it is true that he might have been fond of dogs

will have the same truth value. The same does not in general hold for definite descriptions. If we, like Kripke, account for this difference by means of the intensions of names and descriptions, we have to conclude that names do not in general have the same intension as any normal, identifying description. However, the difference in scope behavior between names and description can be accounted for alternatively by appeal to the semantics of the modal expressions. On the account we suggest, dubbed ‘relational modality’, simple singular terms, like proper names, contribute to modal contexts simply by their actual world reference, not by their (standard) intension. The relational modality account turns out to be fully equivalent with the rigidity account when it comes to truth of modal and non-modal sentences (with respect to the actual world), and hence supports the same basic intuitions. Given an alternative definition of consequence for relational modality, and a restriction to models with reflexive accessibility relations and non-empty world-bound domains, relational modality also turns out to be model theoretically equivalent with rigidity semantics with respect to logical consequence. Here we introduce the semantics, give the truth definition for relational modality models, and prove the equivalence results.