Methuselah's Paradox[Le paradoxe de Mathusalem]

First stated by Cowen (1989), Methuselah's Paradox points to a shortcoming of the standard welfarist approach of the human life cycle. The paradox states that, for any happy life, it is possible to imagine a much longer life, which will generate a higher total well-being, by multiplying a large number of life-years by a very small utility level. This paper uses recent advances in population ethics to reexamine Methuselah's Paradox, and to examine some possible roads to escape from that paradox. It is argued that a convincing solution consists of introducing, following Broome (2004), a critical utility level neutral for the continuation of life. Beyond the examined solutions, Methuselah's Paradox has the merit to raise the question of the right perspective or point of view to be able to provide normative foundations to public policies. This paradox casts also light on possible tensions between different uses of lifetime utility functions, used not only as evaluative tools, but, also, as tools for policy intervention.