ABSTRACT

Edward Zalta has had the foresight to patch up his system in this ad hoc way, to avoid such paradoxes as The Liar, even if that patching up does, limit the system’s self-reference, so that it defeats its own purpose of being necessary to make sense of all scientific theories. Zalta in fact builds his intensional logic around what he sees as the failure of four principles, in the intensional area: Strong Extensionality, objectival, and substitutional Existential Generalisation, and Leibniz’ Law. The paradox Zalta has not avoided is akin to The Liar, but requires the contingent premise that someone only says one thing: ‘Not everything I say is true’. Zalta is concerned with a stronger form of the extensionality principle, and therefore we must consider a stronger form of the second epsilon axiom. A similar point can be made about Zalta’s notion of ‘encoding relation’, and indeed the comparison is even closer than it may at first seem.