This provocative new textbook takes up and develops the themes of rationality and irrationality in Jon Elster's earlier work. Its purposes are threefold. First, Elster shows how belief and preference formation in the realm of politics are shaped by social and political institutions. Second, he argues for an important distinction in the social sciences between mechanisms and theories. Third, he illustrates those general principles of political psychology through readings of three outstanding political psychologists: the French classical historian, Paul Veyne; the Soviet dissident writer, Alexander Zinoviev; the great French political theorist, Alexis de Tocqueville.