Totalism states that one population is better than another iff it has higher total welfare. One counterintuitive consequence is the Repugnant Conclusion (RC). Totalism also entails that a very large population of animals with lives barely worth living is better than a smaller population of happier humans. Furthermore, the strategies that have been used to avoid the troubling normative implications of the RC do not work in the animal case, so we may have reason to bring about such a population. I introduce the notion of ‘Efficiency of Welfare Production’ – that animals of different species vary in the efficiency with which they convert resources into welfare. If we want to maximize total welfare, without any speciesist bias, we should identify which species is most efficient and try to maximize the population of that species. This has counterintuitive implications whether we accept hedonism or a more sophisticated theory of welfare.

A narrowly person-affecting (NPA) axiology is an account of the moral ranking of outcomes such that the comparison of any two outcomes depends on the magnitude and weight of individuals’ well-being gains and losses between the two. This article systematically explores NPA axiology. It argues that NPA axiology yields an outcome ranking that satisfies three fundamental axioms: Pareto, Anonymity and, plausibly, Pigou-Dalton. The axiology is neutral to non-well-being considerations (desert); and (assuming well-being measurability) leads to the Repugnant Conclusion (RC). In short, NPA axiology provides a grounding for Paretian, equity-regarding welfarism, albeit one that includes the RC.

Variable-Value axiologies avoid Parfit’s Repugnant Conclusion while satisfying some weak instances of the Mere Addition principle. We apply calibration methods to two leading members of the family of Variable-Value views conditional upon: first, a very weak instance of Mere Addition and, second, some plausible empirical assumptions about the size and welfare of the intertemporal world population. We find that such facts calibrate these two Variable-Value views to be nearly totalist, and therefore imply conclusions that should seem repugnant to anyone who opposes Total Utilitarianism only due to the Repugnant Conclusion.

We examine a general class of variable-value population principles. Our particular focus is on the extent to which such principles can avoid the repugnant and sadistic conclusions. We show that if a mild limit property is imposed, avoidance of the repugnant conclusion implies the sadistic conclusion. This result generalizes earlier observations by showing that they apply to a substantially larger class of principles. Our second theorem states that, under the limit property, the axiom of mere addition also conflicts with avoidance of the repugnant conclusion. This result is a consequence of a similar observation that appears in the earlier literature.

Lexical views in population axiology can avoid the Repugnant Conclusion without violating Transitivity or Separability. However, they imply a dilemma: either some good life is better than any number of slightly worse lives, or else the ‘at least as good as’ relation on populations is radically incomplete. In this paper, I argue that Archimedean views face an analogous dilemma. I thus conclude that the lexical dilemma gives us little reason to prefer Archimedean views. Even if we give up on lexicality, problems of the same kind remain.