水槽の中の脳を退治する

Abstract

Are we brains in a vat? In the opening chapter of Reason, Truth, and History, Hilary Putnam addresses this brain-in-a-vat skepticism and attempts to refute it. Against his argument is a famous criticism raised by Anthony Brueckner. In this paper, through the analysis of the failure of Putnam's argument, I offer a more promising version of refutation in the form of a transcendental argument. The first section of this article clarifies the distinctive feature which makes the brain-in-a-vat scenario attractive to many people. Thus, attacking the skeptical scenario is thereby clarified as a significant task. In the second section, Putnam's refutation of skepticism is introduced. The only premise which Putnam explicitly adopts is the causal constraint principle, according to which a term refers to an object only if there is an appropriate causal relation between them. Accordingly, Putnam aims to show that the skepticism is self-refuting, that if we can consider whether the sentence “I am a brain in a vat” is true or false, it must be false. In the third section, I consider Brueckner's criticism of Putnam's self-refutation argument. Brueckner claims that for Putnam's argument to succeed, we need to apply the disquotational principle to the sentence. But that begs the question, he argues. I examine why Putnam begs the question and whether he is to blame for this. In the final section, I show that the brain-in-a-vat skepticism cannot be stated without presupposing that it is false by reformulating Putnam's argument as a transcendental argument. I conclude that this skepticism is impossible since it violates the condition of its own possibility.