 For most critics (even within the ranks of logical empiricism), the problem of ruling out metaphysical statements while retaining the terms of high theory remained unsolved. By 1950, in response to the troubles of Ayer’s two attempts to account for the indirect testing of theoretical statements via their consequences, Hempel conceded that it was “useless to continue to search for an adequate criterion of testability in terms of deductive relationships to observation sentences” (1950 [1959, 116]). The following year, Hempel also abandoned the idea of using, as a criterion of empirical significance, Carnap’s method of translatability into an antecedently determined empirical language consisting only of observational non-logical vocabulary. Precisely because it was suitably liberalized to allow abstract scientific theories with merely partial interpretations, its anti-metaphysical edge was blunted: it allowed for combination with “some set of metaphysical propositions, even if the latter have no empirical interpretation at all” (1951, 70). Hempel drew the holistic conclusion that the units of empirical significance were entire theories and that the measure of empirical significance itself was multi-criterial and, moreover, allowed for degrees of significance. To many, this amounted to the demise of the Circle’s anti-metaphysical campaign. By contrast, Feigl’s reaction (1956) was to reduce the ambition of the criterion of significance to the mere provision of necessary conditions.