Why did ideology come to stay as a category of political and philosophical analysis? ‘Ideology at the crossroads of theory’ shows how the illuminating ideas of a few theorists were sustained by concrete political developments. The advent of mass politics in Europe saw the consolidation of traditions of political thought such a liberalism, conservatism, and socialism. These movements and frameworks for political debate began to develop a life of their own, and these political traditions impelled individuals and groups to political action. The philosopher, Wittgenstein, played an important role in the further development of ideology.