I have asymmetric person-affecting intuitions, and I think the Repugnant Conclusion is a clear example of treating individuals as mere vessels/receptacles for value. Sacrificing the welfare of just one person so that another could be born — even if they would be far better off than the first person — seems wrong to me, ignoring other effects. That I could have an obligation to bring people into existence just for their own sake and at an overall personal cost seems wrong to me. The RC just seems like a worse and more extreme version of this.

In a hypothetical world where I'm the only one around, I feel I basically should be allowed to do whatever I want, as long as no one else will come into existence, and I should have no reason to bring them into existence. In my world, I should do whatever I want. If no one is born, I'm not harming anyone else or failing in my obligations to others, because they don't and won't exist to be able to experience harm (or experience an absence of benefit or worse benefits).

That I should make sacrifices to prevent people with bad lives from being born or to help future people who would exist anyway (including ensuring better off people are born instead of worse off people) does seem right to me. If and because these people will exist, I can harm them or fail to prevent harm to them, and that would be bad.

I have some more writing on the asymmetry here.

I'll try to help you understand why (I think) some people feel the sting of the repugnant conclusion (RC), but why I think they are ultimately wrong to do so. I should say that I personally don't find the repugnant conclusion repugnant so what I'm about to say might be completely missing the point. I am slightly stung by the "very repugnant conclusion", but that might be for another time.

In short, I think some people find RC repugnant based on a misunderstanding of what a life "barely worth living" would mean in practice. I think most people imagine such a life to be quite "bad" on the whole, but I think this is a mistake.

Note that the vast majority of people on earth want to continue living. This would include the vast majority of people who live in extreme poverty or who are undergoing horrific abuse. It would also include people who constantly consider suicide to end their pain but never go through with it. In normal parlance we would say these people live "bad" lives. However, we might conclude that these people are living lives worth living if they don't want their life to end / don't choose to end their life. So my guess is people imagine "a life barely worth living" to be a pretty "bad" one. The actual wording of "a life barely worth living" is inherently negative in how it is framed anyway. So RC would amount to a load of people with pretty "bad" lives by intuitive standards, being better than a smaller number of people with absolutely amazing lives. Accepting RC would be like creating another Africa with all it's poverty and hardship instead of creating another Norway with all it's happiness. Or creating loads of people attending daily suicide support groups rather than a smaller number of people living the best lives we can imagine. Most people would find these repugnant things to do and I personally would feel the sting here.

The problem with the above reasoning becomes clear when we think more carefully about "a life barely worth living". Firstly, to state what should be obvious, such a life is worth living by definition. So to be put off by the existence of such lives doesn't really make logical sense, unless you deny the theoretical existence of positive lives in the first place. This doesn't negate people's feeling of repugnance, but I think it should cause them to question it.

Where does this leave us with people attending daily suicide support groups? Well my preferred way forward is to question if these people do in fact have lives worth living, or at least to question if we have any idea on the matter. As is pointed out by Dasgupta (2016), the idea that someone who wants to continue living must be living a life of positive welfare ignores the badness of death. It is certainly possible for someone to be living a life of negative welfare, but be reluctant to end it because the subjective badness of death exceeds the badness of continuing to live. Death is indeed a horrible prospect for most when you consider factors such as religious prohibition, fear of the process of dying, the thought that one would be betraying family and friends, the deep resistance to the idea of taking one’s own life that has been built into us through selection pressure would cause someone even in deep misery to balk, and the revelation of one's misery to others when one wants it to remain undisclosed even after death.

In light of this Dasgupta puts forward the "creation test" as a way to determine the zero-level of wellbeing. What is the worst life that you would willingly create? Dasgupta says that should be the zero level. Most altruists wouldn't create more people living in extreme poverty, or people with constant thoughts of suicide, implying these people probably live negative lives. I personally would only create a life that most of us would say is very good!

I'm not saying Dasgupta's creation test is perfect - I'm undecided on how useful it is. This paper argues that we have no sufficiently clear sense of what a minimally good life is like. If this is indeed true, as the paper argues, the RC loses its probative force because we can not judge lives "barely worth living" as being "bad" as we don't really have a clue.

So to sum up my rather lengthy response, I think that many people who think RC is repugnant assume that "lives barely worth living" are those we would say are "bad" in common parlance which can lead to an understandable feeling of repugnance. I think they are wrong - either "lives barely worth living" are much better than being "bad", in which case RC loses repugnance, or we don't know how good "lives barely worth living" are and RC doesn't even get off the ground at all.

I find your attitude somewhat surprising. I'm much less sympathetic to trolley problems or utility monsters than the repugnant conclusion. I can see why some people aren't moved by it, but I have a hard time seeing how someone couldn't get what it is moving about it. Since it is a rather basic intuition, it's not super easy to pump. But I wonder, what do you think about this alternative, which seems to draw on similar intuitions for me:

Suppose that you could right now, at this moment, choose between continuing to live your life, with all its ups and downs and complexity, or going into a state of near-total suspended animation. In the state of suspended animation, you will have no thoughts and no feelings, except you will have a sensation of sucking on a rather disappointing but not altogether bad cough drop. You won't be able to meditate on your existence, or focus on the different aspects of the flavor. You won't feel pain or boredom. Just the cough drop. If you continue your life, you'll die in 40 years. If you go into the state of animation, it will last for 40,000 years (or 500,000, or 20 million, whatever number it takes.) Is it totally obvious that the right thing to do is to opt for the suspended animation (at least, from a selfish perspective) ?

The term 'repugnant' is unfortunate; I think it's best to focus on whether there's anything morally problematic or deficient about such a world, irrespective of whether it elicits emotions of moral repugnance.

Personally, when I reflect on a universe that only contains experiences of "muzak and potatoes", I feel there's something missing from it, no matter how many such experiences it contains. I'm still willing to bite the bullet and conclude that my feeling is non-veridical, but I do experience the feeling.

One can also consider the parallel situation at the intrapersonal level. Parfit asks us to compare a "Century of Ecstasy" with a "Drab Eternity". I definitely feel the appeal of the former, even if, on reflection, I'd probably opt for the latter. (Though note that Parfit's wording here is also tendentious; a better name for the second option would be a "Mildly Pleasant Eternity".)

But I'm not sure I can describe this feeling more clearly or accurately, though, so this isn't really an answer to your question.

It depends on the formulation. I don't find Parfit's version of the RC, where the people with muzak-and-potatoes lives "never suffer," repugnant. But according to total (symmetric) utilitarianism, that RC is morally equivalent to another version, which I find highly repugnant. Imagine (A) as large and blissful a utopia as you like. Now imagine (Z) a world where many more people than in this utopia each have the following life: for a million years, they endure constant, unbearable torture. After that, they eat potatoes and listen to muzak peacefully for a sufficiently large number of years.

I just don't see how the latter experiences, no matter how many of them, could be considered morally significant in a way that outweighs the torture. You can chalk this up to scope neglect if you want, but (1) my intuitions are definitely not scope-neglectful when comparing suffering to suffering, and (2) I have the same intuition about milder cases where the amount of happiness a classical utilitarian would (probably) accept as outweighing is practically imaginable. e.g. Each person is born experiencing 1 day of depression, then eats potatoes for a normal human lifespan (~30,000 days).

Adding another answer, although I think it's basically pretty similar to my first.

I can imagine myself behind a veil of ignorance, comparing the two populations, even on a small scale, e.g. 2 vs 3 people. In the smaller population with higher average welfare, compared to the larger one with lower average welfare, I imagine myself either

1. as having higher welfare and finding that better, or
2. never existing at all and not caring about that fact, because I wouldn't be around to ever care.

So, overall, the smaller population seems better.

I can make it more concrete, too: optimal family size. A small-scale RC could imply that the optimal family size is larger than the parents and older siblings would prefer (ignoring indirect concerns), and so the parents should have another child even if it means they and their existing children would be worse off and would regret it. That seems wrong to me, because if those extra children are not born, they won't be wronged/worse off, but others will be worse off than otherwise.

In the long run, everyone would become contingent people, too, but then you can apply the same kind of veil of ignorance intuition pump. People can still think a world where family sizes are smaller would have been better, even if they know they wouldn't have personally existed, since they imagine themselves either

1. as someone else (a "counterpart") in that other world, and being better off, or
2. not existing at all (as an "extra" person) in their own world, which doesn't bother them, since they wouldn't have ever been around in the other world to be bothered.

Naively, at least, this seems to have illiberal implications for contraceptives, abortion, etc..

There's also an average utilitarian veil of ignorance intuition pump: imagine yourself as a random person in each of the possible worlds, and notice that your welfare would be higher in expectation in the world with fewer people, and that seems better. (I personally distrust this intuition pump, since average utilitarianism has other implications that seem very wrong to me.)

I have serious doubts about inter-personal trade-offs.
https://www.mattball.org/2021/12/note-and-more-on-ethics-including-case.html
which follows
https://www.mattball.org/2021/12/ethics-is-not-simple-math-problem.html
 

To answer on the level of imagery and associations rather than trying to make a strong philosophical argument: The Repugnant Conclusion makes me think of the dire misery of extremely poor places, like Haiti or Congo. People in extreme poverty are often malnourished, they have to put up with health problems and live in terrible conditions. On top of all those miseries, they have to get through it all with very limited education / access to information, and very limited freedom / agency in life. (But I agree with jackmalde that their lives are nevertheless worth living vs nonexistence -- I would still prefer to live if I was in their situation.)

Compared to an Earth with 10 Billion people living at developed-world standards, it just seems crazy to me that anyone would prefer a world with, say, 1 Trillion people eking out their lives in a trash-strewn Malthusian wasteland. The latter seems like a static world with no variety and no future, without the slack necessary for individuals to appreciate life or for civilization as a whole to grow, explore, learn, and change.

This image leads to various wacky political objections, which are not philosophically relevant since nobody said the Repugnant Conclusion was supposed to apply to the actual situation of Earth in 2021 (as opposed to, say, a hypothetical comparison between 10 Billion rich people vs 3^^^3 lives barely worth living). But emotionally and ideologically, the Repugnant Conclusion brings to mind appropriately aversive images like:

• That EA should pivot away from interventions like GiveDirectly or curing diseases, and instead become all about boosting birthrates in whatever way possible. (New cause area: "Family Disempowerment Media"?)
• That things like the invention of the birth control pill and the broader transition away from strict pro-fertility hierarchical gender norms (starting in the industrial revolution) were some of the worst events in history.
• That almost all human values (art, love, etc) should be sacrificed in favor of supporting a higher total carrying capacity of optimized pure replicators, a la the essay "Meditations on Moloch".

So, in the practical world, the idea that humanity should aim to max out the Earth's carrying capacity without regard to quality-of-life seems insane, so the Repugnant Conclusion will therefore always seem like a bizarre idea totally opposed to ordinary moral reasoning, even if it's technically correct when you use sufficiently big numbers.

Separately from all the above, I also feel that there would be an extreme "samey-ness" to all of these barely-worth-living lives. It seems farfetched to me that you are still adding moral value linearly when you create the quadrillionth person to complete your low-quality-of-life population -- how could their repetitive overlapping experiences match up to the richness and diversity of qualia experienced by a smaller crew of less-deprived humans?

For me (currently with minimalist intuitions), the repugnance depends on whether the lives in the larger population are assumed to never suffer (cf. this section). Judging from the different answers here, people seem to indeed have wildly different interpretations about what those lives feel like.

At one extreme, they could contain absolutely no craving for change and be simply lacking in additional bliss; at the other, they could be roller coaster lives in which extreme craving is assumed to be slightly positively counterbalanced by some of their other moments.

As a practical example, I deny that factory farms could be net positive (all else being equal) regardless of how much bliss the victims could be induced to experience.

A world which supports the maximum number of people has no slack. I instinctively shy away from wanting to be in a world with resource limits that tight.

(Another answer...)

In humans, fertility rates have been declining while average quality of life has been increasing. Considering only human life until now, the RC might suggest things would have been better had fertility rates and average quality of life remained constant, since we'd have far more people with lives worth living. It can undermine the story of human progress, and suggest past trajectories would have been better.

We could also ask whether lifting people out of poverty is good, in case it would lead to lower populations. In general, as incomes increase, people have more access to contraceptives and other family planning services, even if we aren't directly funding such things. (Life-saving interventions would likely not lead to lower populations than otherwise, and would likely lead to higher ones at least in some places, according to research by David Roodman for GiveWell (GiveWell blog post).)

https://en.wikipedia.org/wiki/List_of_countries_by_population_growth_rate

https://en.wikipedia.org/wiki/List_of_sovereign_states_and_dependencies_by_total_fertility_rate

A slightly tongue-in-cheek response: the thought experiment is often introduced by name, and calling it 'repugnant' is priming people to consider it bad, in a way that 'the trolley problem' does not.

I suggest the following thought experiment. Imagine wild animal suffering can be solved. Then it would be possible to populate a square mile with millions of happy insects instead of a few happy human beings. If the repugnant conclusion was true, the best world would be populated with as many insects as possible and only a few human beings that take care that there is no wild animal suffering. 

Even more radical, the best thing to do would be to fill as much of the future light cone as possible with hedonium. Both scenarios do not match the moral intuitions of most people.

If you believe in the opposite, namely that a world with fewer individuals with higher cognitive functions is more worthy, you may arrive at the conclusion that a world populated with a few planet-sized AIs is the best.  

As other people have said, all kinds of population ethics lead to some counter-intuitive conclusions. The most conservative solution is to aim for outcomes that are not bad according to many ethical theories. 

In the maximally repugnant world, no one's life is all that good. I feel the sting of that. It's hard for me to get excited about a world in which all of the people I know personally have barely-net-positive lives full of suffering and struggle, even if that world contains more people.

The Wikipedia page you linked gives a pretty not-upsetting version of the paradox: 

whereas the thing that people find repugnant looks more like:
 

I accept the conclusion, but it feels like I am biting a bullet when I say that World Z is worth fighting for.

Might simply also a big portion of status-quo bias and/or omission bias (here both with similar effect) - be at play, helping to explain the typical classification of the conclusion as repugnant?

I think this might be the case when I ask myself  whether many people who classify the conclusion as repugnant, would not also have classified as just as repugnant the 'opposite' conclusion, if instead they had been offered the same experiment 'the other way round':

Start with a world counting huge numbers of lives worth-living-even-if-barely-so, and propose to destroy them all, for the sake of making very few really rich and happy! (Obviously with the nuance that it is the rich few whose net happiness is slightly larger than the sum of the others). It is just a gut feeling, but I'd guess this would evoke similar types of feelings of repugnance very often (maybe even more so than in the original RC experiment?)! A sort of Repugnant Conclusion 2.

There was a somewhat unusual short philosophical paper this year signed by lots of philosophers which claimed that avoidance of the repugnant conclusion should not be seen as a necessary condition for an adequate population ethics. I guess it's driven by a similar concern you have here: the repugnant conclusion is much less obviously repugnant than its name makes it seem.