When the speaker is a brain-in-a-vat, the argument's conclusion (that the speaker is not a BIV*) is irrelevant to Putnam's desired English-language conclusion
But Brueckner persuasively argues (1986: 164–165) that using the disquotational principle (T) in this context is illegitimate. In effect, (T) as used in this context is ambiguous (see Folina 2016: 159). Depending on whether the speaker is or is not a BIV, (T) will provide different truth conditions for the speaker’s utterances of ‘I am not a BIV’. If the speaker is not a BIV and thus is speaking English in uttering (T), then the truth condition for ‘I am not a BIV’ is just the condition that the