I am deeply indebted to my research assistant, John Borgo, for an ongoing flow of criticism, as well as to my secretary,Diane McDougal, for typing a steady stream of second thoughts. Their work, as well as mine, was supported in part by the Law and Social Science Division of The National Science Foundation. The Foundation,however, should not be held responsible for the views expressed in this essay.I am also very grateful to my many friends at Yale and elsewhere who helped me with this book. But my debts here are so numerous and diverse as to defy a comprehensive and exact accounting.