 Even though the formalist project became identified with mainstream logical empiricism generally (consider its prominence in confirmation theory and in the theory of explanation), it was not universally subscribed to in the Vienna Circle itself. In different ways, neither Schlick nor Neurath or Frank adhered to it. As noted in the overview above, Schlick’s attempts to exhibit natural language meaning abjured efforts to characterize it in explicitly formal terms, even though he accepted the demand for necessary and sufficient conditions of significance. In the end, moreover, Schlick turned away from his colleagues’ search for a criterion of empirical significance. In allowing talk of life after death as meaningful (1936a), for the very reason that what speaks against it is only the empirical impossibility of verifying such talk, Schlick’s final criterion clearly left empiricist strictures behind.