The notion of rationality is examined with respect to its use in economics. Three kinds of rationality are distinguished. First, economics is qualified as rational when its nomological-deductive content is taken into account. Second, agents and actions are qualified as rational if a theory of choice is introduced related to a system of binary relations of preference. Third, a preference system on a set of lotteries, acts or strategies is qualified as rational if it is consistent with a theory that connects choice to its possible consequences. Moreover, in all these matters a double meaning of rationality applies, either as logical consistency or as conformity to an axiomatic model.