Meaning and Interchangeability

Abstract

This dissertation focuses on the notion of synonymy, or identity of meaning, applied to monadic predicates. Beginning with an examination of W. V. Quine's remarks about synonymy in "Two Dogmas of Empiricism," it then considers interchangeability salva veritate, interpreted in various different formal languages, as a possible criterion of synonymy. The languages considered have the structure of (i) first order logic, (ii) quantified modal logic, in particular S5, (iii) a language obtained by supplementing first order logic with doxastic operators of the form "Speaker s believes that ..." for each speaker of the language, and (iv) a quantified polymodal logic which contains both modal and doxastic operators. A positive result is achieved in that it is argued that synonymy can identified with interchangeability salva veritate in language (iv). Furthermore, ISV in (iv) is shown to correspond to a proposition in that language affirming that two predicates cannot possibly be the predicates of divergent beliefs.