This book evolved out of a paper given to the Moral Sciences Club in Cambridge in 1979. The ideas in that paper were later developed in talks given in Glasgow, Edinburgh and St Andrews, until they swelled into the immediate precursor of this book: my Oxford D.Phil, thesis, submitted in 1982. It is a pleasure to thank my thesis supervisor, Malcolm Budd, for his extremely exhaustive and illuminating comments on every aspect of my project. I also profited from the reactions of my examiners, Richard Wollheim and David Wiggins. Many people have tried to make this a better book by advancing suggestions and criticisms at various moments of truth: I thank especially John Skorupski, Dudley Knowles, Frank Sibley, Eva Schaper, Warren Goldfarb and Tom Ricketts. The comments of the referees for Cambridge University Press have been most valuable. Any shockers that remain are of my own doing.