Book excerpt: Normal Rationality is a selection of the most important work of Edna Ullmann-Margalit, presenting some influential and widely admired essays alongside some that are not well known. She was an unorthodox and deeply original philosopher whose work illuminated the largest mysteries of human life. Much of her writing focuses on two fundamental questions. (1) How do people proceed when they cannot act on the basis of reasons, or project likely consequences? (2) How is social order possible? Ullmann-Margalit's answers, emphasizing what might be called biased rationality, are important not only for philosophy, but also for political science, psychology, sociology, cognitive science, economics (including behavioral economics), law, and even public policy. Ullmann-Margalit demonstrates that people have identifiable strategies for making difficult decisions, whether the question is small (what to buy at a supermarket) or big (whether to transform one's life in some large-scale way). She also shows that social dilemmas are solved by norms; that invisible-hand explanations take two identifiable (and dramatically different) forms; that trust can emerge in seemingly unpromising situations; and that considerateness is the foundation on which our relationships are organized in both the thin context of the public space and the intimate context of the family. One of the distinguishing features of Ullmann-Margalit's work is its close attention to the details of human experience, and its use of those details to offer fresh understandings of social phenomena. Her essays cast new light on a diverse assortment of problems in philosophy, social science, and individual lives.