 An argument for B(3) has yet to be given, but there are two on offer. The first opens with the remark that, since EXT requires water for thinking “water is wet” (as all parties are currently allowing), the same is true of the self-attributing thought “I’m thinking that water is wet.” (Davies 2000 2003a, 2003b). However, if a person regards this metaphysical claim as warranted along with (2) —then she cannot rationally put (3) in doubt. For if the existence of water were in doubt, then given her warranted metaphysical claim, this rationally compels a further doubt on whether the thought expressed by (2) exists in the first place. But the existence of the thought must be acknowledged before one can concede a warrant to it. So our externalist will rationally allow a warrant to both *premises only if she already assumes (3) as background, which is just what B(3)says.