Jurgen Habermas was born in 1929 in Dusseldorf and studied philosophy, history, psychology and German Literature in Gotttingen, Zurich and Bonn. He was under the sway of Martin Heidegger until 1953. In this year he read the newly published Introduction to Metaphysics. He was shocked by Heidegger's lack of comment on the Nazi period. Habermas was then inspired first by Lukacs' History and Class Consciousness which he read in 1954 and secondly by Adorno & Horkheimer's Dialectic of the Enlightenment which he came across in 1955.
He got a job at the Frankfurt Institute as an assistant in 1956. By 1962 he had risen to become a Professor whilst writing his influential 'Structural Transformations of the Public Sphere'. He left Frankfurt University in 1971 after disputes with students in the protest movement but returned in 1982.
Habermas considers the split between theory and practice in the Marxist tradition in his book Theory and Practice (1963). In this book he agrees with the later Adorno in seeing a limitation for human action in the central Marxist concept of labour. Labour produces a view of human beings as solely the subject of alienation. He argued that this was only part of the picture and one that had denied a truly liberating perspective to Marxism.
Beginning in the early 1970's, Habermas rejected Adorno's aesthetic orientation and began arguing for a reorientation of critical theory towards a renewed collaboration between philosophy and the social sciences. (Benhabib et al, 1993 p11)
His attempt to see a human potential beyond the alienation of labour and to revive the founding cross disciplinary principles of Critical Social Theory led to his magnum opus which was published in 1981 as The Theory of Communicative Action. This is the work to which I will now refer.
The subtitle of volume one is 'Reason and the Rationalisation of Society'. The study of reason has traditionally belonged to philosophy and philosophical reason can most simply be defined as an unpacking of reason's experience of itself. However reason is difficult to define any more than saying that it is thinking codified in language. Referring to Richard Rorty, Habermas agrees with the postmodernist position that a philosophical worldview has become untenable and that there can no longer be a totalising abstract knowledge. However Habermas argues that it does not then follow that an empirically tested theory of rationality could not be universal.
As the search for ultimate foundations by 'first philosophy' or 'The Philosophy of Consciousness' has now broken down, this must be a pragmatic theory based on science and social science. This implies that any universalist claims can only be validated by testing against counter examples in historical (and geographical) contexts - not by using transcendental ontological assumptions.
This leads him to look for the basis of a new theory of communicative action in the tradition of sociology.
 Introduction to Metaphysics was based on a lecture that Heidegger had given in 1935.
 See, Habermas: an introduction, Detlef Horster, (Pennbridge 1992 p82)
 It is clear from the essays collected in On Max Horkheimer, (op cit) that Habermas owes a huge debt to the influence of Max Horkheimer's original programme at the Frankfurt Institute.
 Page numbers given refer to the Polity Press English translation by Thomas McCarthy (paperback edition of 1986).