One of the main original aims of philosophy was to give us guidance about how to live our lives. The ancient Greeks typically assumed that a life led in accordance with reason, a rational life, would also be the happiest or most fulfilling. Ingmar Persson’s book resumes this project, which has been largely neglected in contemporary philosophy. But his conclusions are very different; by exploring the irrationality of our attitudes to time, our identity, and ourresponsibility, Persson shows that the aim of living rationally conflicts not only with the aim of leading the most fulfilling life, but also with the moral aim of promoting the maximization and just distribution of fulfilment for all. Persson also argues that neither the aim of living rationally nor anyof the fulfilment aims can be rejected as less rational than any other. We thus face a dilemma of either having to enter a retreat of reason, insulated from everyday attitudes, or making reason retreat from its aspiration to be the sole controller of our attitudes. The Retreat of Reason explores three areas in which there is a conflict between the rational life and a life dedicated to maximization of fulfilment. Persson contends that living rationally requires us to give up, first, our temporal biases; secondly, our bias towards ourselves; and, thirdly, our responsibility to the extent that it involves the notion of desert and desert-entailing notions. But giving up these attitudes is so overwhelmingly hard that the effort to do so not onlymakes our own lives less fulfilling, but also obstructs our efficient pursuit of the moral aim of promoting a maximum of justly distributed fulfilment. Ingmar Persson brings back to philosophy the ambition of offering a broad vision of the human condition. The Retreat of Reason challenges and disturbs some of our most fundamental ideas about ourselves.