 When discussing the status of bridge-principles (intuitively, statements that connect the vocabulary of the reducing theory to the reduced theory), Ernest Nagel suggested that they might play different roles in the discovery of reductions than in after the fact analyses. They may function as hypotheses to be tested, or they may rely on empirical evidence already gathered. Similarly, Kenneth Schaffner suggests that an appropriate model of reduction should take into account not only logical or metaphysical aspects regarding the reduced and the reducing theory. Rather, it should also be sensitive to pragmatic and epistemic aspects underlying the actions of scientists who carry out reductions (Schaffner 1993: 515f.)—an idea he labels ‘logical pragmatism’. New Wave reductionists criticized other models, especially Nagel’s, for not being adequately sensitive to how reductions are actually carried out, a point also made by Ager, Aronson, and Weingard (1974).