Habermas's critique of Enlightenment reason is linked to a more constructive concern, which brings him into line with the critical theory of the Frankfurt School. This is why he expects to find, within modern reason itself, a completely different figure, complementary to the former and capable of extending modern rationality to the dimensions of intercomprehension. In so far as he invokes communicational reason, Habermas intends to go beyond the paradigm of the philosophy of the subject.We have diagnosed the sites of reason in Habermas's thought, while inscribing it in the contextual register that situates him in relation to the Frankfurt School; we have also examined the connection between the concept of reason and critical theory, in order to shed light on the relationship between the philosophical tradition and the new formulation of a critical theory of society legitimized by the emancipatory interests of knowledge.