Despite the resurgence of interest in the issue in political science, the impact of democratic liberation on political innovation remains poorly understood. In particular, three questions can be asked: Where do the new ideas of justice being circulated come from and why do they emerge at certain moments and places? What are the conditions for success and what role is played by social actors? And what room does an open interpretation of conceptions of justice and democratic deliberation leave for structures, historical context, interests, and culture? This article reviews the usual explanations provided by social sciences, offers an interpretation of deliberation and political innovation that draws from Keynes, Marx and moral realism, and examines the case of the American New Deal to clarify the sense of the proposed interpretation.