Rank-Additive Population Ethics

The class of "rank-additive" (RA) axiologies includes rank-weighted utilitarian, generalized utilitarian, and rank-discounted generalized utilitarian rules; it is a flexible framework for population ethics. This paper axiomatically characterizes RA axiologies and studies their properties in two frameworks: the "actualist" framework (which only tracks the utilities of people who actually exist), and the "possibilist" framework (which also assigns zero utilities to people who don’t exist). The axiomatizations and properties are quite different in the two frameworks. For example, actualist RA axiologies can simultaneously evade the Repugnant Conclusion and promote equality, whereas in the possibilist framework, there is a tradeoff between these two desiderata. On the other hand, possibilist RA axiologies satisfy the Positive Expansion and Negative Expansion axioms, whereas the actualist ones don’t