Problems of Rationality is the eagerly awaited fourth volume of Donald Davidson's philosophical writings. From the 1960s until his death in August 2003 Davidson was perhaps the most influential figure in English-language philosophy, and his work has had a profound effect upon the discipline. His unified theory of the interpretation of thought, meaning, and action holds that rationality is a necessary condition for both mind and interpretation. Davidson here develops this theory to illuminate value judgements and how we understand them; to investigate what the conditions are for attributing mental states to an object or creature; and to grapple with the problems presented by thoughts and actions which seem to be irrational. Anyone working on knowledge, mind, and language will find these essays essential reading.