Habermas, the leading second-generation Frankfurt School theorist, developed a theory of communicative rationality grounded in the conditions of undistorted rational argumentation, on which validity claims to truth, rightness, and sincerity are redeemed through uncoerced consensus among participants treated as equals. In "The Theory of Communicative Action" (1981) he distinguished this communicative action from strategic action oriented to success, and diagnosed a modern pathology in which market and bureaucratic systems increasingly "colonize" the communicatively structured lifeworld of everyday interaction.
Intellectual setting
Habermas inherited and reworked the critical theory of Adorno and Horkheimer, moving away from their more pessimistic diagnosis of instrumental reason toward a "postmetaphysical" theory of communicative rationality capable of grounding both social critique and a positive theory of democratic legitimacy.
Key ideas
Communicative rationality and the ideal speech situation
Habermas argued that claims to truth, moral rightness, and sincerity are ultimately validated through free, uncoerced rational discourse among participants as equals, an idealized "ideal speech situation" that provides a normative standard for legitimate argument and democratic deliberation.
Colonization of the lifeworld
Habermas argued that in modern societies, the instrumental logics of the economic market and state bureaucracy increasingly displace communicatively achieved mutual understanding in everyday social life, a process he called the colonization of the lifeworld.
Legacy
Habermas is among the most influential living philosophers, shaping deliberative democratic theory, discourse ethics, and contemporary sociology and legal theory, and extending the critical theory tradition's project of reason-based social critique into a new register.