ABSTRACT
Previous chapters have dealt mainly with theory. This one takes a step toward application. It defines concepts essential to welfare aggregation over populations, then introduces, explains, and defends two special axioms (the aggregation axiom and the zero axiom) that characterize them. The zero axiom proves essential to intersituational comparison, buounds are useful in deducing non-obvious information about the welfare of populations, and Hasse diagrams provide means for detecting fallacies. Contrary to the views of some economists, even if interpersonal welfare comparison is impossible (which it isn’t) that would not preclude some forms of intersituational aggregation and comparison. A common formulation of the Pareto principle turns out to be false for nonlinear value structures, yet a weaker version remains true. The discussion then turns to the wide-ranging debate sparked by Derek Parfit over aggregate welfare comparison among situations with different populations, including those involving procreation. The zero axiom has clear implications for this debate, and objections to these implications are rebutted. The final section considers the significance for the value of a life of welfare values incomparable with zero.
