Readers of Jurgen Habermas's Theory of Communicative Action and his later social theory know that the idea of communicative rationality is central to his version of critical theory. Language and Reason opens up new territory for social theorists by providing the first general introduction to Habermas's program of formal pragmatics: his reconstruction of the universal principles of possible understanding that, he argues, are already operative in everyday communicative practices. Philosophers of language will discover surprising and fruitful connections between Habermas's account of language and validity (especially his theory of meaning) and their own concerns.