Article published in the first volume of the philosophy journal Aperto Animo. Available here.
Abstract:
Let Reductionism be the correct account of personal identity. How does that change, or constrain our views in ethical theory? In this paper, I presuppose a popular account of Reductionism, the psychological criterion of personal identity, and explore its implications to ethical theory. First, I argue that this view most plausibly implies the extreme view, according to which the ethically significant metaphysical units are momentary experiences. I then argue that the extreme view appropriately responds to the nonidentity problem via rejecting the person-affecting view. I then defend that the extreme view provides support to utilitarianism. Moreover, the extreme view results in the so-called Repugnant conclusion, which says that for any population with very high welfare, there is a population containing more individuals with lives which are barely worth living whose existence, all else equal, is better. I then defend the extreme view’s plausibility in face of this result.
I agree that the extreme view is inconsistent with "the person-affecting view" (the specific principle), or at least, conscious wellbeing would no longer be action-guiding, but there are other "person-affecting views" that would still be action-guiding and also avoid the repugnant conclusion when applied to "atoms", "person-moments" or individual experiences.
It's possible to both satisfy the procreation asymmetry and "solve" the nonidentity problem, with a wide asymmetric person-affecting view, at the cost of the independence of irrelevant alternatives, see
Or, with a narrow asymmetric person-affecting view, i.e. being indifferent when both experiences would be "positive", but choosing against the worst off one when it is negative, only negative states would matter. Negative utilitarianism could be founded on such a view. See also tranquilism, and this thread on my shortform.
You could also have something like a wide necessitarianism, which would "solve" the nonidentity problem but have nothing to say about whether adding extra experiences is good or bad (assuming no effects on others), regardless of their welfare. At the level of persons, I think Teruji Thomas' paper discusses this, and Christopher Meacham's approach could probably be modified for this, too. See also Dasgupta's approach, described in "The welfare economics of population" by John Broome, which could be combined with something like Meacham's counterpart relations.
Thank you very much for this great reply! I'll certainly check them out once I get back to thinking about population ethics.
I do want to make clear that the approach I took in this paper was one of seeing what views and implications would "flow" from reductionism, rather than one of finding the best theory to accommodate our existing moral intuitions in light of some new fact.