The following is the abstract of my paper "Moral pluralism versus the total view: why Singer is wrong about radical life extension", just published in The Journal of Medical Ethics :
Peter Singer has argued that we should not proceed with a hypothetical life-extension drug, based on a scenario in which developing the drug would fail to achieve the greatest sum of happiness over time. However, this is the wrong test. If we ask, more simply, which policy would be more benevolent, we reach a different conclusion from Singer’s: even given his (admittedly questionable) scenario, development of the drug should go ahead. Singer’s rigorous utilitarian position pushes him in the direction of an implausible “total view” utilitarianism when it encounters the problems presented by certain thought experiments. A more pluralistic account of the nature of morality promises to solve these problems, and in this case it reaches a benevolent recommendation on life-extension technology.
I argue that, given the kind of scenario stipulated by Singer, we should proceed to develop the life-extension drug.