Abstract

Derek Parfit's Reasons and Persons is a long, difficult and fascinating book, inside which three shorter, clearer and better books are struggling to get out. The third of these shorter but better books deals with the problem of Future Generations, and that is the book I want to discuss. In it Parfit tries, but fails, to find a theory—Theory X, he calls it—which will deal with various problems and issues which he develops, and in particular the issue which I will call the Parfit Population Problem, the problem of how many people there ought to be. In this paper I offer not so much a theory as a suggestion as to what the solution might be