Quasi-orderings and population ethics

Population ethics contains several principles that avoid the repugnant conclusion. These rules rank all possible alternatives, leaving no room for moral ambiguity. Building on a suggestion of Parfit, this paper characterizes principles that provide incomplete but ethically attractive rankings of alternatives with different population sizes. All of them rank same-number alternatives with generalized utilitarianism.This paper was presented to the conference Incommensurability and Value, Château du Baffy, Caen, April 1994, and an earlier version was presented at the Applied Ethics Centre of the University of British Columbia. We are indebted to John Broome, whose comments inspired this paper, Alan Gibbard, James Griffin, Peter Hammond, Adam Morton, Klaus Nehring, and conference and seminar participants for comments and suggestions. Financial support through a grant from the Social Sciences and Humanities Research Council of Canada is gratefully acknowledged