 Quine points out that we want to be able to generalize on the embedded sentences in those conditionals, by semantically ascending, abstracting logical form, and deriving (A). But, as Tarski (ibid.) notes, this feat cannot be achieved, given only a commitment to (the instances of) (T). From (T) and (A), we can prove (B) and (C) but, given the finitude of deduction, when equipped only with the instances of (T), we cannot prove (A). As a consequence of the Compactness Theorem of first-order logic, anything provable from the totality of the instances of (T) is provable from just finitely many of them, so any theory that takes the totality of the instances of (T) to characterize truth will be unable to prove any generalization like (A).