Abstract

The hypothesis that we are brains in a vat is one which we believe to be false. Could it possibly be true, however? Metaphysical realists accept that our believing it to be false does not entail its falsity. They also accept that if –as brains in a vat –we were to say or think “We are brains in a vat”, then we would be correct. Ever the claimed foe of the metaphysical realist, though, Hilary Putnam argues that the brains‐in‐a‐vat hypothesis cannot be true, in particular that if we were brains in a vat then we could not correctly say or think that we were like that. I will defend metaphysical realism against Putnam's argument.