Seven chapters of this book were once published as articles: they reappear here in (sometimes extensively) altered form. Four chapters, and the Introduction, are new. But the whole book represents a single intellectual journey. It displays the development of my response to the challenge posed to my once dogmatic socialist convictions by libertarian political philosophy.

In coping with that challenge, and in writing this book, my greatest debt has been to Arnold Zuboff, who convinced me to drop many misconceived ideas and who helped me to sharpen those that survived his scrutiny. I am also grateful to the members (Pranab Bardhan, Sam Bowles, Bob Brenner, John Roemer, Hillel Steiner, Robert van der Veen, Philippe Van Parijs, and Erik Wright) of the September or (as it is sometimes called) Non-Bullshit Marxism Group, who raked through early versions of most of the chapters. Daniel Attas, Ronnie Dworkin, Susan Hurley, David Miller, Derek Parfit, Alan Patten, Joseph Raz, Amartya Sen, Andrew Williams, and Bernard Williams made excellent criticisms at Oxford meetings. My former students Chris Bertram and Jo Wolff read the penultimate draft and offered penetrating observations and liberating suggestions. Dozens of friends and colleagues outside Oxford commented orally and in writing at different stages of the development of much of the material, but I have culpably failed to keep a complete running account of their contributions.