This lecture explores the limits of politics in three senses: as a subject of study at Cambridge, as an academic discipline, and as a practical activity. Politics did not develop as an independent academic subject in Cambridge in the twentieth century, and only now is this situation being rectified with the creation of the new Department of Politics and International Studies. Politics as an academic discipline was once conceived as the master science. More recently it has become much more limited in its scope and its methods, but it still needs to preserve a tradition of political reasoning which focuses on problems rather than methodology, and is concerned with understanding the limits to politics. The limits of politics as a practical activity are explored through four modes of political reasoning: the sceptical, the idealist, the rationalist and the realist, as exemplified by the writings of Oakeshott, Keynes, Hayek, and Carr.