LAW AND CONTEMPORARY PROBLEMS

Over the last decade or so, rational choice theory has begun to transform the study of U.S. political institutions. The key to its success is methodological. What it offers, above all else, is a distinctively economic way of exploring a whole range of institutional issues-from government organization to political control to performance and accountability-that political scientists have long approached in less productive ways. As the movement for a new institutionalism has swept political analysis, rational choice has taken the lead in challenging the past and charting new paths for the future.1 Analytically, this is all to the good. Substantively, however, there is something amiss in what rational choice actually has to say about U.S. political institutions. For while the institutional system has itself been transformed over the past century, evolving from a nineteenth century system of "congressional government"2 into a modern, presidentially led bureaucratic state,3 the basic thrust of rational choice theory today fails to explain these developments adequately. The hallmark of modern U.S. government is presidential leadership. Yet positive theorists have never known quite what to do with presidents. On