Political Legitimacy: Realism in Political Theory and Sociology explores the concept of political legitimacy, the nature of the normative foundation of politics and the state. With particular attention to the broad theoretical approach of political realism within political theory and political sociology, it examines the work of figures including Bernard Williams, Raymond Geuss, John Grey, Max Weber, and Niklas Luhmann, among others. Contending that in the face of the waning influence of political idealism, the insights of political realism constitute a promising way forward, the author also advances the view that realist political theory would benefit from sociological insights, particularly on the nature of the state. As such, Political Legitimacy will appeal to scholars and students of social and political theory, political sociology, and political philosophy.