Abstract

It seems to be a widespread opinion that increasing the length of existing happy lives is better than creating new happy lives although the total welfare is the same in both cases, and that it may be better even when the total welfare is lower in the outcome with extended lives. I shall discuss two interesting suggestions that seem to support this idea. Firstly, the idea there is a positive level of well-being above which a life has to reach to have positive contributive value to a population. This view is usually called critical level utilitarianism. Secondly, the viewthat it makes an outcome worse if people are worse off than they otherwise could have been. I shall call this view comparativism. Firstly, I shall describe what I call the pure case of life extension versus replacement. Then I shall very briefly describe some different views about the value of life extension and indicate why I think some of the arguments in favor and against life extension fail. I shall then turn to the implications of critical level utilitarianism and comparativism in regards to life extension versus replacement, which is the main topic of this chapter.