tl;dr: Total utilitarianism treats saving lives and creating new lives as equivalent (all else equal). This seems wrong: funding fertility is not an adequate substitute for bednets.  We can avoid this result by giving separate weight to both person-directed and undirected (or "impersonal") reasons. We have weak impersonal reasons to bring an extra life into existence, while we have both impersonal and person-directed reasons to aid an existing individual. This commonsense alternative to totalism still entails longtermism, as zillions of weak impersonal reasons to bring new lives into existence can add up to overwhelmingly strong reasons to prevent human extinction.

Killing vs Failing to Create

I think the strongest objection to total utilitarianism is that it risks collapsing the theoretical distinction between killing and failing to create. (Of course, there would still be good practical reasons to maintain such a distinction in practice; but I think there’s a principled distinction here that our theories ought to accommodate.) While I think it’s straightforwardly good to bring more awesome lives into existence, and so failing to create an awesome life constitutes a missed opportunity for doing good, premature death is not just a “missed opportunity” for a good future, it’s harmful in a way that should especially concern us.

For example, we clearly have much stronger moral reasons to save the life of a young child (e.g. by funding anti-malarial bednets) than to simply cause an extra child to exist (e.g. by funding fertility treatments or incentivizing procreation). If totalism can’t accommodate this moral datum, that would seem a serious problem for the view.

How can we best accommodate this datum? I think there may be two distinct intuitions in the vicinity that I’d want to accommodate:

(1) Something about the intrinsic badness of (undesired) death.
(2) Counting both person-directed and undirected (“impersonal”) moral reasons.

The Intrinsic Harm of Death

Most of the harm of death is comparative: not bad in itself, but worse than the alternative of living on. Importantly, we only have reason to avoid comparative harms in ways that secure the better alternative. To see this, suppose that if you save a child’s life, they’ll live two more decades and then die from an illness that robs them of five decades more life. That latter death is then really bad for them. Does it follow that you shouldn’t save the child’s life after all (since it exposes them to a more harmful death later)? Of course not. The later death is worse compared to living the five decades extra, but letting them die now would do them even less good, no matter that the early death — in depriving them of just two decades of life — is not “as bad” (comparatively speaking) as the later death would be (in a different context with a different point of comparison).

So we should not aim to minimize comparative harms of this sort: that would lead us badly astray. But it’s a tricky question whether the harm of death is purely comparative. In ‘Value Receptacles’ (2015, p. 323), I argued that it plausibly is not:

Besides preventing the creation of future goods, death is also positively disvaluable insofar as it involves the interruption and thwarting of important life plans, projects, and goals. If such thwarting has sufficient disvalue, it could well outweigh the slight increase in hedonic value obtained in the replacement scenario [where one person is “struck down in the prime of life and replaced with a marginally happier substitute”].

Thwarted goals and projects may make death positively bad to some extent. But the extent must be limited. However tragic it is to die in one’s teens (say), I don’t think one could plausibly say that it’s so bad as to render the person’s life overall not worth living. The goods of life can fairly easily outweigh the harm of death, I believe.

It’s a tricky question where exactly to draw the line here. Suppose a couple undergoing fertility treatment learns that all of their potential embryos have a genetic defect that would inevitably result in painless death while the child is still very young. That obviously gives the parents strong prudential reasons to refrain from procreating and suffering the immense grief that would soon follow. But if we bracket others’ interests, and focus purely on the interests of the potential child themselves: is it ever the case that an overall-happy life, however short, is not worth living, purely due to the fact of death? I could, of course, imagine a painful death outweighing the happiness of a very short life. But suppose the death is painless, or at any rate is nowhere near to outweighing the prior joy the life contains. Yet it does thwart the child’s plans and projects. Is that so bad that it would have been better for them to never exist at all? I find that hard to believe.

For another test: imagine a future society that uses artificial wombs to procreate (and parents aren’t notified until the entire process is successfully completed). Suppose some fetuses have a congenital condition that causes them to painlessly die almost immediately after first acquiring sentience (or whatever is required for morally relevant interests of a sort that makes death harmful for them). How much should the society be willing to invest in diagnostic testing to instead allow the defective embryos to be aborted prior to acquiring moral interests? (Or, at greater cost, to test the gametes prior to fertilization?) Could preventing short but painless existence ever take priority over other societal goals like saving lives and reducing suffering?

We probably can’t give that much weight to the intrinsic harm of (painless) death, if it’s never enough to make non-existence look especially desirable in comparison. So I think we may need to look elsewhere to find stronger reasons.

Person-Directed and Undirected Reasons

Much population ethics discourse sets up a false dichotomy between the two extremes of impersonal total utilitarianism and narrow person-affecting views on which we’ve no reason to bring happy lives into existence. I find this very strange, since a far more intuitive middle-ground view would acknowledge that we have both person-directed and undirected (or “impersonal”) reasons.

Failing to create a person does not harm or wrong that individual in the way that negatively affecting their interests (e.g. by killing them as a young adult) does.  Contraception isn't murder, and neither is abstinence. Person-directed reasons explain this common-sense distinction: we have especially strong reasons not to harm or wrong particular individuals.

But avoiding wrongs isn't all that matters.  There's always some (albeit weaker) reason to positively benefit possible future people by bringing them into a positive existence, even though it doesn't wrong anyone to remain childless by choice.

And when you multiply those individually weak reasons by zillions, you can end up with overwhelmingly strong reasons to prevent human extinction, just as longtermists claim. (This reason is so strong it would plausibly be wrong to neglect or violate it, even though it does not wrong any particular individual. Just as the non-identity problem shows that one outcome can be worse than another without necessarily being worse for any particular individual.)

On this hybrid view, which I defend in more detail in ‘Rethinking the Asymmetry’ (2017), we are warranted in some degree of partiality towards the antecedently actual. We have weak impersonal reasons to bring an extra life into existence, while we have both impersonal and person-directed reasons to aid an existing individual (or a future individual who is certain to exist independently of our present decision).

Conclusion

I think this hybrid view is very commonsensical. We all agree that you can harm someone by bringing them into a miserable existence, so there’s no basis for denying that you can benefit someone by bringing them into a happy existence. It would be crazy to claim that there is literally no reason to do the latter. And there is no theoretical advantage to making this crazy claim. (As I explain in ‘Puzzles for Everyone’, it doesn’t solve the repugnant conclusion, because we need a solution that works for the intra-personal case — and whatever does the trick there will automatically carry over to the interpersonal version too.) So the narrow person-affecting view really does strike me as entirely unmotivated.

But, as indicated above, this very natural hybrid view still entails the basic longtermist claim that we’ve very strong moral reasons to care about the distant future (and strongly prefer flourishing civilization over extinction). So the notion that longtermism depends on stark totalism is simply a mistake.

Totalism is on the right track when it comes to many big-picture questions, but it is an oversimplification. Failing to create is importantly morally different from killing. We have especially stringent reasons to avoid the latter. (It's an interesting further question precisely how much extra weight we should give to saving lives over creating lives.) But we still have some moral reason to want good lives to come into existence, and that adds up to very strong moral reasons to care about the future of humanity in its entirety.