During the time between the world wars, democracy fell into crisis. Communism and fascism offered models of an alternative modernity. Contrary to what the decline of political liberalism might suggest, the intellectual debates of that time regarding the foundations of democracy are an essential part of political theory. Jens Hacke's brilliant study of intellectual history illustrates how ideas developed since the 1920s were meant to shape the world after 1945 and claim new relevance in light of current crisis phenomena: the theory of totalitarianism, the concept of defensive democracy, and the notion of a regulated capitalism.