Abstract

It is often maintained that co-referential terms can be substituted for one another whilst preserving truth-value in extensional contexts, and preserving grammaticality in all contexts. Crispin Wright calls this claim ‘The Reference Principle’ . Since Wright defines extensional contexts as those in which truth-value is determined only by reference, it is the assertion about substitution salva congruitate that is significant. Wright argues that RP is the key to understanding how Frege came to hold, paradoxically, that the concept horse is not a concept, and to providing a resolution to the paradox .RP and Wright's application of it to Frege's Paradox have recently been criticized by Oliver . 1 Oliver argues that the syntax of natural languages is too complicated for the failure of two terms to fit into the same forms of speech to indicate a difference in semantic significance: RP is, he claims, an empirical falsehood.I shall argue that, although Oliver's arguments show that RP is false as it stands, a revised version of the principle, employing a more robust notion of substitution, is nevertheless correct. I shall end by outlining the implications of this revision for the appeal to RP and for Wright's resolution of Frege's Paradox.1. Referring terms and referential positionOliver's case against RP appeals to an impressive array of counter-examples. For our purposes it will be useful to regard these as being of three sorts. The first sort can be dealt with relatively swiftly: examples of the second and third sorts are more challenging.The first sort of counter-example involves referring terms that feature as parts of complex referring expressions. Oliver's examples include ‘William’ in the complex expression ‘William the Conqueror’ . The substitution of expressions co-referential with ‘William’ into sentences employing the complex referring expression often results in ungrammatical ….