Since the early 1960s until his death in the summer of 2003, Donald Davidson was arguably the most influential philosopher of the English language. With "Problems of Rationality," the fourth volume of his philosophical writings is now available in German translation, marking another step in Davidson's journey towards "a unified theory of thought, meaning, and action." The essay of the same title serves as the programmatic centerpiece of this volume. According to Davidson's general thesis, rationality is a necessary condition for interpreting, that is, understanding the thoughts, speech, and actions of others, and it plays a crucial role in the question of which beings we can attribute a mind to. In further essays, Davidson applies this thesis to the question of the objectivity of values and wonders whether there is a science of rationality.