Hilary putnam has tried to refute the realist doctrine that the operational verification of a theory never logically precludes its objective falsity by means of an argument involving model-theoretic considerations. in this paper it is first shown that this argument does not work if the theory in question is open to revision. next it is argued that a realist need not and should not admit the notion of the sort of unrevisable, ideal theory required for the purposes of putnam's argument.