The Theory of Communicative Action (German: Theorie des kommunikativen Handelns) is a two-volume 1981 book by the philosopher Jürgen Habermas, in which the author continues his project of finding a way to ground "the social sciences in a theory of language", which had been set out in On the Logic of the Social Sciences (1967). The two volumes are Reason and the Rationalization of Society (Handlungsrationalität und gesellschaftliche Rationalisierung), in which Habermas establishes a concept of communicative rationality, and Lifeworld and System: A Critique of Functionalist Reason (Zur Kritik der funktionalistischen Vernunft), in which Habermas creates the two level concept of society and lays out the critical theory for modernity.After writing The Theory of Communicative Action, Habermas expanded upon the theory of communicative action by using it as the basis of his theory of morality, democracy, and law. The work has inspired many responses by social theorists and philosophers, and in 1998 was listed by the International Sociological Association as the eighth most important sociological book of the 20th century. Source: Wikipedia (en)