Habermas burst onto the German intellectual scene in the 1950s with an influential critique of the philosophy of Martin Heidegger. He studied philosophy and sociology under the critical theorists Max Horkheimer and Theodor Adorno at the Institute for Social Research at the Johann Wolfgang von Goethe university in Frankfurt am Main before becoming professor of philosophy at the University of Heidelberg and then at Frankfurt.
Habermas accepted the position of Director of the Max Planck Institute in Starnberg (near Munich) in 1971, and worked there until 1983, two years after the publication of his magnum opus, The Theory of Communicative Action. Habermas then returned to his chair at Frankfurt and the directorship of the Institute for Social Research. Since retiring from Frankfurt in 1993, Habermas has continued to publish extensively.
Habermas's main aim has been to construct a social theory that is also a non-oppressive and inclusive universalist moral framework. The framework rests on the argument that all speech acts have an inherent telos--the goal of mutual understanding, and that human beings possess the communicative competence to bring about such understanding. Habermas built the framework out of the speech-act philosophy of Austin and Searle, the theories of moral development of Jean Piaget and Lawrence Kohlberg, and the discourse ethics of his Heidelberg colleague Karl-Otto Apel.
Within sociology, Habermas's major contribution is the development of a comprehensive theory of societal evolution and modernization focusing on the difference between communicative rationality and rationalization on the one hand and strategic/instrumental rationality and rationalization on the other. This includes a critique from a communicative standpoint of the differentiation-based theory of social systems developed by Niklas Luhmann, a student of Parsons. His defence of modern society and civil society has been a source of inspiration to others, and is considered a major philosophical alternative to the varieties of poststructuralism. He has also offered an influential analysis of late capitalism. Habermas sees the rationalization, humanization, and democratization of society in terms of the institutionalization of the rationality potential that is inherent in the communicative competence that is specific to the human species, has developed through the course of evolution, but in contemporary society is suppressed or weakened by the way in which major domains of social life, such as the market, the state, and organizations, have been given over to or taken over by strategic/instrumental rationality, so that the logic of the system supplants that of the lifeworld.
Habermas is famous as a teacher and mentor. Among his most prominent students have been the political sociologist Claus Offe (professor at Humboldt University in Berlin), the sociological theorist Hans Joas (professor at the Free University of Berlin and at the University of Chicago), the theorist of societal evolution Klaus Eder, the social philosopher Axel Honneth (the current director of the Institute for Social Research), and the American philosopher Thomas McCarthy.
Habermas is famous as a public intellectual as well as a scholar, and has used the popular press to attack neoconservative historians who have tried to relativize or lessen the importance of the Holocaust. He is perhaps most famous outside of Germany for his conceptualization of the public sphere.