VAGUENESS, LOGIC AND TRUTH

Hilary Putnam has suggested that logic and metaphysics are intimately connected so that logic is dependent upon metaphysics. According to Putnam, the validity of classical logic depends upon the truth of metaphysical realism, whereas the truth of metaphysical anti-realism will justify only some alternative to classical logic. Moreover, if Putnam's suggestion is correct, then even an attempt to defend one semantics of vagueness over another must include a defense of some metaphysical view.;Finally, my defense of supervaluation semantics has consequences for the prosentential theory of truth. That theory is shown to be incompatible with supervaluation semantic. I also examine some classical many-valued semantics and find them either inadequate for vague natural language or incompatible with the prosentential theory. I conclude that the prosentential theorist is severely limited when it comes to selecting a semantics for natural language.;My project began as an attempt to find some grounds for preferring one semantics of vagueness over the others. Many semantics for vague languages have been offered in the literature. Two such semantics which have received attention are supervaluation semantics, which justifies classical logic and the Lakoff-Zadeh many-valued semantics, which does not. There has been varied praise and criticism of each of these approaches, yet no consensus has arisen as to which semantics is to be preferred. I argue that logic is not dependent upon metaphysics in the way Putnam suggests it is. The justification of logic, in fact, depends upon our linguistic practice. I then use this claim to show that supervaluation semantics is preferable to the Lakoff-Zadeh semantics for natural language.