The Putnam's proof against radical skepticism: Two interpretations based on self-knowledge

I present and defend two reinterpretations of Putnam's proof that we are not brains in a vat. Both of them make explicit the role played in it by selfknowledge of our own thoughts and the role played by content externalism. The first one takes externalism as implying that a brain in a vat cannot have the relevant content (involving concepts about brains and vats). The other version only extracts from externalism a weaker thesis that a bodily subject and a brain in a vat cannot share the relevant content.