The concept of rationality, predominantly in the guise of rational choice theory, plays a key role in the social sciences. Yet, whilst rational choice theory is usually understood as part of positive political science, it is also widely employed within normative political theories. In this paper, we examine how allegedly positive rational choice arguments can find application within normative political theories. To this effect, we distinguish between two interpretations of rationality ascriptions, one empirical, the other normative. Since, as we demonstrate, (...) empirical readings of the rationality assumption cannot convincingly explain the role of rational choice arguments in normative theories, we argue that the rationality assumption should be given a normative interpretation. We conclude by considering what this result implies for the use of rational choice arguments in normative and positive political science. (shrink)