 But Friedman draws a much more radical conclusion. In his terminology, the mistake economists make who criticize claims such as “firms attempt to maximize profits” lies in the attempt to test theories by the “realism” of their “assumptions” rather than by the accuracy of their predictions. He maintains that the realism of a theory’s assumptions is irrelevant to its predictive value. It does not matter whether the assumption that firms maximize profits is realistic. Theories should be appraised exclusively in terms of the accuracy of their predictions. What matters is exclusively whether the theory of the firm makes correct and significant predictions.