Elliott Thornley


According to Neutral-Set Views in population axiology, some number of lifetime welfare levels are contributively neutral. Adding a life at these levels to a population makes that population neither better nor worse. If just one welfare level is neutral, the view counts as a Neutral-Level View. Adding a life at this level leaves the new population equally good as the original. If more than one welfare level is neutral, the view counts as a Neutral-Range View. Adding a life within this range renders the new population incommensurable with the original.

In this paper, I sharpen some old objections to these views and offer some new ones. Neutral-Level Views cannot avoid certain Repugnant and Sadistic Conclusions. Neutral-Range Views imply that lives featuring no good or bad components whatsoever can nevertheless swallow up and neutralise goodness and badness. Both classes of view entail that certain small changes in welfare correspond to worryingly large differences in contributive value.

I then offer a new view that retains much of the appeal of Neutral-Set Views while avoiding the above pitfalls. On the Imprecise Exchange Rates View, the quantity of some good required to outweigh a given unit of some bad is imprecise. This imprecision is the source of incommensurability between lives and populations.