Neither mentioning 'brains in a vat' nor mentioning brains in a vat will prove that we are not brains in a vat

In Reason, Truth, and History Hilary Putnam has presented an anti-skeptical argument purporting to prove that we are not brains in a vat. How exactly the argument goes is somewhat controversial. A number of competing "recon¬structions" have been proposed. They suffer from a defect which they share with what seems to be Putnam's own version of the argument. In this paper, I examine a very simple and rather natural reconstruction of the argument, one that does not employ any premises in which a sentence, viz. the sentence 'I am a brain in a vat', is mentioned rather than used. In this respect my version of the argument is importantly different from what appears to be Putnam's own version.