It is fairly normal and natural to associate negative utilitarianism — the doctrine that we should minimize the amount of suffering in the world — with antinatalism. The reasoning from the one to the other is (or seems) pretty straightforward. Everyone, even very happy, fortunate people, can be expected to have at least some suffering in their lives. So if we add people to the world, we add suffering to the world. Therefore we should refrain from adding new people to the world.
Under many realistic conditions this reasoning is likely to be sound, but there can be exceptions which are worthy of attention if different people have complementary existences. Consider a simple (if fanciful) example. On Planet Eden there is only one person, Lonely Adam. In his life there will be ten units of suffering. Much of Lonely Adam’s suffering is due precisely to the fact that he is lonely. If he had a companion, he would have only five units of suffering in his life. Suppose a Utilitarian Demiurge oversees Planet Eden and has the capacity to create Cheerful Eve, who will have only one unit of suffering in her life. In a hypothetical Eden containing both Lonely Adam and Cheerful Eve, there will be therefore 5 + 1 = 6 units of suffering, which is less than the ten units Adam would otherwise have had to bear. The Utilitarian Demiurge would thus seem to have a compelling reason for creating the new person Cheerful Eve.
It might be objected that there is something obnoxious about the creation of Cheerful Eve, for example that Cheerful Eve is being somehow treated as a means to relieve Lonely Adam’s suffering. Kantians think this is a lethal objection. I see this “problem” as a general feature of consequentialist ethical theories and tend to be unimpressed by it. It is certainly not the case that Cheerful Eve is just some sort of object here — her suffering does count in any sensible deliberation about what to do (it would be forbidden to create her, for example, if her life would contain six units of suffering). More generally it seems easily justifiable to interfere with people’s existences all the time. If we humanely incapacitate a serial rapist (say, by warehousing him a in virtual reality for the rest of days where he can assault NPCs rather than real people to his heart’s content), then we are surely in some sense treating as a means for achieving the well-being of others (most importantly his would-be future victims). But seriously, I don’t have a problem with that, not even if he simply couldn’t have helped being a serial rapist to begin with.
If we consider interpersonal complementarities, we can even specify conditions under which the continued creation of new people seem like a good idea. Consider an imagined World of Progress. Every new person suffers some in their existence and so by coming into existence adds to the world’s stock of suffering. But unlike in our world where new people suffer about as much (and sometimes more) than existing people, in the World of Progress the suffering of new people declines on the margin the following fashion. That is, the first new person added will have a units of suffering in her life, the second new person will have ar2 units (r < 1), the third ar3, and so forth.
It doesn’t take a math genius (which is lucky for me, as I am not one) to see that what we have here is a convergent geometric series.
It has a sum that is a finite value. If it is also a property of the World of Progress that the amount of suffering reduced in people existing before the creation of the first new person by means of having the sequence of new people come into existence, then we have constructed a set of conditions under which we would want to create an infinite number of new people, even if we accept negative utilitarianism and even if each new person adds some suffering to the world.
I must say this strikes me as a counterintuitive result. I very much doubt it has any immediate applicability to the world we actually live in, although there are possible worlds in which it matters.
Something like this result might motivate what I have called in commentary discussion with CM and JasonSL the High Threshold View,, that is, the view that it is not wrong to create new people if they will have a very high quality of life (or, in negative utilitarian terms, very little suffering in their lives). After all (to the extent that we have negative utilitarian intuitions, anyway) there is at least some argument for bringing into existence people who will experience little suffering (like Cheerful Eve) and help relieve the suffering of others. The more suffering they have in their lives, the more dubious the argument for their being brought into existence becomes. There might also be a link to the attractions of posthumanism here: the better our technology, the more our world would resemble a World of Progress (which does look a bit like what I’ve called Future P, although it is not necessarily identical to it) and the less the world we actually, and unfortunately, have to live in.