A lady once asked Dr Johnson why he had defined ‘pastern’ in his dictionary as a horse's knee. ‘Ignorance, madam, pure ignorance’, the sage replied. Readers, seeing that this book is by a philosopher and light on footnotes, may wonder if my grasp of economics, politics and sociology can be relied on. Let me set their minds at rest: it cannot. This is an argumentative text, which poaches not in order to teach experts their business but to borrow from them and enlist their philosophical curiosity. All the same, I shall be presuming on their good nature. Where they disagree, I hope that they will stop to reason with me. Where they could have put the points better themselves, I hope that they will.

If I need not always echo Dr Johnson, it is thanks mainly to friends and colleagues. Shaun Hargreaves-Heap in particular has kindly read the manuscript with an economist's eye and suggested many improvements. This is in addition to the explicit debt of chapter 7 and parts of later chapters to our published articles. Frank Hahn and Edward Nell are two other economists with whom I have enjoyed working and whose company and writings have influenced the text. My chief debt in politics is to Steve Smith and to our joint teaching, which yielded the article drawn on throughout chapter 10. In sociology I owe much to the pleasures of teaching for several years with Bryan Heading and Gareth Jones. Among my fellow philosophers, Tim O'Hagan and Philip Pettit have long been especially helpful comrades.