INTRODUCTION

In Reason, Truth and History (1981), Hilary Putnam offers two rejoinders to the skeptical conjecture that we might all be ‘brains in a vat.’ The first is that the ‘brains in a vat’ hypothesis is self-refuting: were we brains in a vat, we could not possibly be expressing a truth when we said we were brains in a vat, hence the ‘brains in a vat’ hypothesis must be false. This argument rests on the conception of meaning developed in “The Meaning of ‘Meaning.’” The second rejoinder is considerably simpler: “Internalist philosophers dismiss the ‘Brains in a Vat’ hypothesis. For us, the ‘Brains in a Vat World’ is only a story, a mere linguistic construction, and not a possible world at all” (1981, p. 50). These rejoinders reflect two different strategies for confronting skepticism Putnam adopted over the years, one in his earlier writings, the other in more recent works. Reason, Truth and History is thus Janus-faced: the apotheosis of the first strategy, it also ushers in the second. This essay will examine the shift from one strategy to the other, demonstrating the continuity in their underlying motivations. Putnam's conception of meaning, I will show, played a major role in these developments, taking Putnam from the thesis that skepticism is false to the thesis that it is senseless. To substantiate my claims, I explore Putnam's responses to skepticism about scientific truth, skepticism about meaning, and skepticism about necessary truth.