Proponents argue that rational choice theory is a form of positive science, one whose simplified model of the human psyche generates useful predictions of human behavior. But their assumptions are contrary to fact. Their analyses of public policy decisions are cast in terms of the sharp and now largely discredited distinction logical positivists drew between "facts" and "values" or efficient "means" and affective "ends." And their models arouse suspicions concerning and objections to the political and psychological effects of the methods they employ and the policy options they endorse. All of this makes the theory not only less useful for understanding politics but also more subject to criticism by "postmodern" thinkers than it need be. Were its proponents explicitly to acknowledge the "prescriptive" character of "rational choice," however, they would help foster a broader discussion of the diferent kinds of rationality and their interaction in the formulation of public policy. That discussion of the forms of rationality would, in turn, bring out a more complex view of the psychological basis of both politics and rationality. The understanding of reason employed by rational choice theorists is quite narrow, consisting merely in calculations of the most efficient means of achieving any given end. It presupposes a rather simple model of the human psyche in which one part or faculty (reason) figures out how to satisfy the greatest number of an individual's "preferences," understood to be primarily, if not simply, products of another aspect or function, the affective, at the least cost. Neither such calculations nor a broader notion of "reason," which would include deliberation or judgment as well as calculation, is thought to have any significant role in the formation or articulation of these preferences. Adopting the tenets of what is often called "methodological individualism," rational choice theorists treat *I would like to acknowledge the support of the Social Philosophy and Policy Center, Bowling Green