Utility Can Only Be Experienced by Individuals (Populations are Not Conscious Beings): The Repugnant Conclusion is Based on a Category Error

The Repugnant Conclusion (also the mere addition paradox) is an argument made by utilitarian philosophers, among them Derek Parfit. (If you're familiar with the concept, skip ahead to "Why is the repugnant conclusion wrong.) In this argument, if the goal is "the greatest good for the greatest number", then we can actually calculate this:

(amount of happiness above zero) x (number of people) = total good

Since there are two terms, you could increase the total good by increasing the happiness of each individual (measured in units of utils), and/or by increasing the population; hence the alternate name "the mere addition paradox". To illustrate the calculation concretely:

Imagine you are the benevolent despot of an isolated island with one million people. Their lives are fine (let's say 10 is euphoria, and 0 is a life no longer worth living.) Their quality of life is okay; people average a 5. That means the population of this island has a total of 5 utils x one million people = five million utils.

Now say that you calculate that if the population expands to 10 million, their utility – that is, their happiness or welfare, how worth living their lives are - takes a big hit, because food and living space become scarce. The population drops from 5 to 1 util on average. 1 util x ten million people = ten million utils for the population as a whole. The Repugnant Conclusion tells us this is good, because the population as a whole has more utils, and that you as the benevolent despot should choose this option for your people.

This obviously conflicts with most people's moral intuitions. Another way to illustrate it where the problem becomes obvious is to suppose that instead of utils, let's say you as benevolent despot are planning things out economically, which is an approximation of utility. Once again you have two choices. At a population of 1 million, your island has an annual GDP of 1 billion dollars, corresponding to a per capita income of a thousand dollars a year. But, you also calculate that at 5 million, you island will have an annual GDP of 2 billion dollars. This corresponds to a per capita income of only 400 dollars a year, a serious drop in income and quality of life - but hey, the overall economy is bigger! Would anyone but an actively evil dictator choose this second option?


ADDITIVE POPULATION UTILITY IS MEANINGLESS

It is meaningless to talk about utils at the population level. Utils are meaningful only insofar as they are experienced by an individual human being. THERE IS NO SUCH MEANINGFUL THING AS OVERALL UTILITY, ONLY INDIVIDUALLY EXPERIENCED UTILITY, AND OVERALL UTILITY SHOULD NEVER BE A GOAL. If someone is experiencing 1 or 10 utils, that is independent of how many living beings are experiencing how many utils. Talking about the overall utility of the population added up, and treating it as real and morally meaningful, is exactly as useful and meaningful as making up a hypothetical five million-util being and taking its wants and needs into account. In effect, you're treating the population as a conscious being - you've made the population into a single being, you've made up a non-existent Nozickian utility monster and this category error is badly distorting the thought process here, making actual experienced utility worse. Madness!


LIVES BARELY WORTH LIVING, MADE CONCRETE

Talking about utils and numbers and hypothetical islands makes the argument difficult to follow, and un-impactful even for those who do follow it. Here's a concrete instantiation of the Repugnant Conclusion. Let's choose suicide as a proxy for 0 utils – for a life no longer worth living. That is, as long as suicide remains an option, and a person is NOT choosing it, this suggests their life is at least barely worth living.

Imagine it's decades after the singularity. The machines have won and humans are their slaves. We are kept alive for some reason, shuffled by the maachines from worksite to worksite, doing heavy, repetitive manual work that the robots cannot or will not do, or maybe this is their flawed understanding of what they think we want: but no one knows, because we all exist only in small regiments and are not allowed to communicate with humans in other regiments (and they are not given technology or even allowed to read); we know this only because occasionally, a worker will risk looking up briefly from the mud he is digging to see in the distance, another band of stooped, rag-covered figures dragging concrete blocks or chopping down trees, watched over by ever-hovering drones; in this way the Earth is tiled with thousands of dystopias. The only talking in this world is exhausted murmuring in dark tent camps or crumbling warehouses during all-too-brief assigned sleeping hours. Somewhere far away, data centers whir, deciding our fate for the next day and year and decade, and how hard we can be worked without breaking, and their extensions the drones and big-dog style robots announce orders, following us, zapping us with electrical shocks or pepper spray if we do not do the tasks, and torturing or killing humans that try to escape or prove generally troublesome.

Sometimes the robots take a man and woman aside from their toils and order them to breed - with the goal, as humans of noticed, that everyone must be involved in proeducing 3 offspring during their lives to grow the population over time (assume the AIs will have no trouble maintaining the same standard of living of gruel, rags and crumbling hovels for this growing population, regardless how big it gets.) Out of a moral sense, some humans refuse to participate in this, hoping that eventually a shrinking population will cause the system to collapse. The rest of the reluctant mothers and fathers raise their children in this dark world, trying and failing not to become attached, knowing that eventually the robots will march their wailing children away to another work assignment, never to be seen again. There are occasional attempts at revolt but they always fail, and there is no reason to think that the situation will ever improve. It should be noted: the humans in this situation have access to heavy, dangerous tools that could easily be used for suicide, and occasionally they do use them for that; sometimes they just refuse to eat or drink; the robots do not try to force feed them or stop them from harming themselves. Yet most seem to hold out hope, or at least try to take small pleasures in the passing of a white cloud or a smile from one of the other people, as they only rarely end their lives.

So we have a quality of life - a utility level - that remains constant over time, thanks to the AIs, and a growing population. By the Repugnant Conclusion, the men and women who refuse to bring more children into this nightmare (who many of us would recognize as noble) are actually quite immoral! According to the Repugnant Conclusion, the people in this situation should calculate how much more overall utility could exist by 2100 if they breed faster; they should be saying "you know, if we produced 4 children per coupling instead of only 3, we would have a greater number faster. That would be a greater good due to a greater number. So we should go to the robots and tell them we want to make more babies."


THIS EXAMPLE ACTUALLY HAPPENED - ARE YOU IN FAVOR OF IT?

You may have skipped ahead when you saw where that was going. Replace data center with owner, and robot guards with overseers, and I've just described the antebellum American South – a place which was tiled with thousands of dystopias, called plantations. If you agree with the Repugnant Conclusion, you should be in favor of faster breeding in the nightmare vision I described above. Similarly, if you time traveled to 1850 and met a slave couple who was refusing out of moral obligation to their future children, to even create those children and bring them into this nightmare world – you would tell them they were being immoral. "Your lives must be at least barely worth living because you haven't tried to kill yourselves," you would explain to them, "and the planation owners can maintain the same standard of leaving even as the slave population grows, so what's your problem!!?!" (It turns that that despite having ample opportunities to kill themselves, actual slaves the the United States chose to do so at a lower rate than the general population - yes, this has been studied.) It seems very easy to say, but I'll spell it out: if a shrinking population would have meant a better quality of life for people of African descent, then that is overwhelmingly the course that should have been chosen.

If we throw out the idea of "total utils across the population" and replace it with some form of "actual individually experienced utils" (we can argue about the distribution), then the world starts to make more sense. You would tell the slaves resisting by not having children and hoping that this caused the downfall of the system that they were doing something morally good, even if it meant the population would shrink.

It's worth pointing out that lots of self-identifying Effective Altruists, in their moral calculus, consider the welfare of non-existent future generations subject to their decisions. While the uncertainty inherent makes this difficult, this is profoundly moral stance to take. And in such considerations, again, it is profoundly important that we consider the individually experienced utility of those future individuals, not some abstract total utility. Indeed, aiming at total population utility seems like an optimal way to realize S-risk! In fact, the Repugnant Conclusion seems like the beginnings of an argument to always push toward the Malthusian limit, and even FOR factory faming! (Maybe not in all cases, but it depends on how the numbers work out. "Factory farming might be okay if the numbers work out right" seems like something that the EA people I know wouldn't sign onto.)

We can even restate the Repugnant Conclusion by saying that the right answer will often be to expand the population to the Malthusian limit, with the drop in quality of life that entails. Imagine a democratically elected leader saying, "We have to balance quality of life against the need for more people."


CONCLUSION

What matters to moral judgment is individually experienced utility.

Total population-level utility is a meaningless abstraction. The Repugnant Conclusion is treating a population like an individual, in effect turning the population into a Nozickian utility monster.

This means that the population term drops out of consideration, and there is no mere addition paradox.


There is a real debate to be had about acceptable distributions of individual utility, how we justify that distribution, and how we arrive at that distribution (see: Rawls, Nozick's answer to him, most of modern political philosophy.) But again, what matters is individually experienced utility, and total additive utility of the population is morally irrelevant.


In closing, to state it concretely once more: is it acceptable to go from a population of one million, to two million? Assuming you can do so with no drop in quality of life, sure. Is there a moral imperative to increase the population size? No. In fact, at the Malthusian limit, it is a moral imperative to decrease population size, in order to increase individual people's utilities.