No problem. It’s always good to see people getting into population ethics.
>>maybe there’s a different “fix” altogether that avoids both issues.
Unfortunately, there isn’t. Specifically, consider the following three conditions:
1) A condition encoding avoidance of what you call the “birth paradox” (usually called the Mere Addition Principle)
2) Another condition which prevents us from being radically elitist in the sense that we prefer to give LESS wellbeing to people who already have a lot, rather than MORE wellbeing to people who have less. (Notice that this can be stated without appealing to the importance of “total wellbeing”—I just did it earlier as a convenient shorthand.) These conditions are usually called things like “Non Anti-Egalitarianism”, “Pigou-Dalton”, or “Non-Elitism”.
3) Transitivity.
It can be shown that every population satisfying these three conditions implies the Repugnant Conclusion. There’s also a big literature on impossibility results for avoiding the Repugnant Conclusion, and to cut a long story short, these conditions (1), (2) and (3) can be weakened or replaced.
If you’re interested in this topic, I would recommend trying to slog through some of the extensive literature first, if you haven’t already. A good place to start is Hilary Greaves’ Philosophy Compass article, “Population Axiology”.
If you find that article interesting, you can follow up some of the references there. There’s a precise and easy-to-follow rendition of the original Mere Addition Paradox in Ng (1989), “What should we do about future generations? Impossibility of Parfit’s Theory X”. And I think Parfit’s original discussion of population ethics in Reasons and Persons (part 4) is still well worth reading, even if it’s outdated in some regards.
The most important discussion of impossibility theorems is in an unpublished manuscript by Gustaf Arrhenius, “Population Ethics: The Challenge of Future Generations”. The main results in that book are also published in papers from 2003, 2009 and 2011. The 2022 Spears/Budolfson paper, “Repugnant Conclusions”, is also well worth a read in my opinion, as is Jacob Nebel’s “An Intrapersonal Addition Paradox” (2019 I think). Jake also has a very nice paper, “Totalism Without Repugnance”, where he puts forward a lexical view and tries to answer some of the standard objections to them.
As you’ve stated the view, I think it would violate transitivity. Consider the following three populations, where each position in the vector denotes the wellbeing of a specific person, and a dash represents the case where that person does not exist:
A: (2, 1)
A’: (1, 2)
B: (2, -)
A is better than (or perhaps equally as good as?) B, because we match the first person with themselves, then settle by comparing the second person at 1 (in A) to non-existence in B. You didn’t say how exactly to do this, but I assume A is supposed to be at least as good as B, since that’s what you wanted to say (and I guess you mean to say that it’s better).
However, A and A’ are equally good.
Transitivity would entail that A’ is therefore at least as good as B, but on the procedure you described, A is worse than B because we compare them first according to wellbeing levels for those who exist in both, and the first person exists in both and is better off in B.
I don’t doubt that the view can be modified to solve this problem, but it’s common in population ethics that solving one problem creates another.
I probably won’t reply further, by the way—just because I don’t go on EA forums much. Best of luck.