The Primacy of the Classical? Saul Kripke Meets Niels Bohr

ABSTRACT Kripke's theory of partial truth offers a natural solution of the Liar paradox and an appealing explanation of why the Liar sentence seems to lack definite content. It seems vulnerable, however, to the objection that it cannot state important facts about partial truth. I point out that the same vulnerability infects the quantum logic developed by Garrett Birkhoff and John von Neumann, among others. It is often claimed that the only way to record these facts is within a classical metalanguage, but Kripke showed that the same language can function both as the language of partial truth and also as a classically bivalent language. An explanation of why we need a classical explanation of a non-classical system was advanced in the context of quantum mechanics by Niels Bohr, and it applies also, I argue, to the partial truth situation.