On the occasion of Habermas's 80th birthday, the German publisher Suhrkamp brought out five volumes of Habermas's work that spanned the full range his philosophical work, from the theory of rationality to the critique of metaphysics. For each of these volumes, Habermas wrote an introduction that crystallized, in a remarkably clear and succinct way, his thinking on the key philosophical issues that have preoccupied him throughout his long career. This new book by Polity brings together these five introductions and publishes them together for the first time. The result is a unique and comprehensive overview of Habermas's philosophy in his own words. In the five chapters that make up this volume, Habermas discusses the concept of communicative action and the grounding of the social sciences in the theory of language; the relationship between rationality and the theory of language; discourse ethics; political theory and problems of democracy and legitimacy; the critique of reason and the challenge posed by religion in a secular age. The volume includes a substantial introduction by Jean-Marc Durand-Gasselin which provides the reader with all the necessary background to understand Habermas's distinctive and original contribution to philosophy. Philosophical Introductions will be an indispensable text for students and scholars in philosophy and in the humanities and social sciences generally, and for anyone interested in the most important developments in philosophy and critical theory today.