Extension and replacement

Abstract Many people believe that it is better to extend the length of a happy life than to create a new happy life, even if the total welfare is the same in both cases. Despite the popularity of this view, one would be hard-pressed to find a fully compelling justification for it in the literature. This paper develops a novel account of why and when extension is better than replacement that applies not just to persons but also to non-human animals and humanity as a whole.