Normally, consent is considered as essential for norm formation and social praxis in a modern democratic society. Consent with good reasons is also the basis for Habermas’ communicative ethics and political philosophy for a modern democratic society. His theory is based on the idea of a well-functioning democratic society. In Weber’s sense, we could talk about a sociological idealtype. However, even in this ideal-typical theory, Habermas introduces the concept of dissent, the possibility to say no, “Das Nein-sagen-Können”, as the basis for the ultimate freedom. This ultimate freedom to say No is essential in many social conflicts in totalitarian institutions and totalitarian societies. Dissent is also essential for social movements in a modern democratic society. The focus is on dissent as a basic political philosophical concept for the understanding of norm conflicts, norm formations and social praxis.