Here is my question:
“Is a world with 10 billion people twice as good as a world with 5 billion people?”
This question was asked by Giles Fraser during the Intelligence Squared debate, in an attempt to challenge the core assumption of the Effective Altruism movement (that saving lives makes the world better). He directed it to William MacAskill. I heard MacAskill’s reply, but he did not really address the heart of the question there.
This is a very important issue for the movement and not merely a theoretical puzzle.
If the answer is “Yes, a world with 10 billion people is twice as good,” then one could rebut by saying, “You might claim that, but a world with 10 billion people has less food, healthcare, and overall resources per person.”
If the answer is “No, a world with 10 billion people is not better than a world with 5 billion,” then it seems to open the door to justifying murder (or preventing births) as “the most effective thing to do.”
Please answer the two questions—I have not (after a lot of thinking) found a way to resolve this paradox:
Is a world with 10 billion people twice as good as a world with 5 billion people?
Does saving people really make the world better?
This is an important and valuable question, thank you for raising it. I’ll split my observations into two effects:
Malthusian effects
Benefits of scale
Malthusian effects
Other responses have referred to Malthusian effects, by which I mean the concern that with only finite resources, the resources will be spread between more people, and each person will have a worse quality of life.
Benefits of scale
Creating another person doesn’t only create another mouth to feed. It also creates another source of ideas and creativity.
For example, each new birth has the potential to become another Norman Borlaug (who is claimed to have saved a billion lives through his research).
Even if 999,999 new people fail to come up with a ground-breaking innovation which makes the world better, if the millionth person does, it could allow everyone to benefit.
Of course, the flipside is that any new person could be the next Hitler/Stalin/insert-your-favourite-bad-guy-here.
Are the Norman Borlaugs winning over the Hitlers?
If you believe the data that seem to suggest that the world has been getting better over recent centuries, the answer seems to be yes.
There’s also benefits around the fact that niche interests/needs are better accommodated at scale. If 0.01% of the population has a rare disease, and the population is 10 billion people, that’s a million sufferers—enough scale to incentivise scientific research. And if successful, maybe everyone is cured/treated. For a significantly smaller population that disease may remain untreated for a very long time.
Do the benefits of scale win over the Malthusian effects?
I don’t think this is obvious, but I’m inclined to think the benefits of scale win.
If we look at recent examples of challenges that humanity has faced, human ingenuity has managed a few good successes (the aforementioned example of Norman Borlaug and dwarf wheat; the cost effectiveness of solar power has improved dramatically in recent years; smallpox eradication; saving the ozone layer). Don’t get me wrong, we still have more to do! But that suggests we want more brains, not less.
Furthermore, decisions we make today should be based on how the benefits of scale will work in the future, not how they were in the past. Will we be better able to use our ingenuity to solve big problems in the future? Some would argue that AI will make us better able to explore creative new solutions (not that everyone will agree on this).
Lastly, and this isn’t really answering your question, but rather picking up on a comment of yours. You said that the idea that saving lives makes the world better is a “core assumption of the effective altruism movement”. I don’t think this is correct. EA is a movement built around using evidence and reason to do good. If the evidence showed that saving lives was bad, the essence of EA would be unchanged. Furthermore, lots of the practice would be unchanged too—a lot of EA activity is not linked to saving lives.
Thank you for laying out the “Malthusian effects” vs. “benefits of scale” framework so clearly. As someone engaging with the Effective Altruism movement’s ideas from an outside perspective, I find this a helpful way to structure the problem.
However, from my viewpoint, I have a deep concern with the “benefits of scale” argument as it’s presented. When we justify adding a million people by the chance that one of them might be the next Norman Borlaug, we are judging human lives based on their instrumental value—what they might produce for the rest of us.
This framing implicitly creates a hierarchy of human worth. The value of the 999,999 non-innovators becomes secondary, justified only by the possibility of the one “genius” they might help produce. They become a means to an end, not ends in themselves.
This is precisely the logic that opens the door to eugenics. To be clear on what I mean by this, eugenics is the belief that humanity can and should be improved by controlling reproduction—encouraging births among those with “desirable” traits while discouraging or preventing births among those with “undesirable” traits. At its very core, it is a system of valuing people instrumentally based on their perceived biological or social fitness.
If we accept the principle that a person’s worth is tied to their potential intelligence or creativity, what logical principle stops us from concluding that lives with less of that potential are less worth creating or protecting?
This brings me back to my central concern. For an observer like myself, it seems the only robust defense against these incredibly dangerous historical ideas is to build an ethical framework based on the inherent value of every single life, regardless of whether that person becomes a saviour or lives a simple, ordinary existence.
I think a non-paradoxical answer is: “a world with 10 billion people is better, but probably not twice as good”.
The reason it might not be quite twice as good is because of the resource issues you mention, that might decrease average welfare.
You might be right that the world doesn’t have to be twice as good just because it has twice as many people. But if you agree that a world with more people is better than one with fewer people, then what happens when I increase the population to 20B? At some point, you don’t get a better world—you get a world where everyone is suffering and starving due to lack of resources. The paradox remains: if “more lives = better world” leads to unbearable conditions, can we really say it’s better?
If you care about maximizing total welfare, then you will think adding extra people to the population is better until the point where the harm they do to others (via using up scarce resources) outweighs the good from creating the extra person. I don’t know where that point is, but it’s not obvious that it is a point where ‘everyone is suffering and starving’.
If you care about total welfare, then it is true that for any concievable state of the world, there is always a hypothetical better state of the world in which everyone’s lives are only barely worth living, but the population is so large that the total amount of welfare is still higher. This is the repugnant conclusion.
The repugnant conclusion is a problem for people who claim to care about total welfare. But you can reject the repugnant conclusion without being forced to conclude that saving people makes the world worse. For example, person affecting views hold that an act can only be good or bad if it is good or bad for someone. Stopping someone from being born is not bad for anyone, because the hypothetical child does not exist. On the other hand, saving someone who already exists might still be seen as very good. The two things do not have to be treated as equivalent.
Person-affecting views have different problems (the non-identity problem, and giving non-transitive ranking of outcomes). But they avoid the repugnant conclusion without implying that saving people is bad.
Or perhaps I’m missing the point of your question completely, and it is more practical than theoretical. Are you just getting at the practical concern that saving lives will increase the current population, and that at its current level this is a bad thing? Like Ian Turner said, this then becomes a complicated empirical question about what the actual effect of saving lives on the population is. I don’t know if the answer to that is clear.
Also, even if you think adding an extra person by creating a new life does more harm than good on the margin in today’s world, and you believe that saving a life increases the population, it does not necessarily follow that saving a life also does more harm than good, because saving lives also has other big effects (e.g. if someone who already exists dies then the family and friends who are left behind suffer greatly).
I didn’t fully understand your opinion, but I noticed you’re not against the principle of stopping births. My concern is that this line of thinking can open the gates to very dangerous ideas.
If you accept that saving people isn’t always good, or that preventing certain births can be morally justified, then it becomes possible to argue that we should stop genetically defected people from having children—also for the “greater good.” Just like one might argue we should prevent births to avoid suffering, one could now argue that we should prevent certain types of people from being born in order to “improve humanity.”
This is a very slippery slope. It might start with the idea of doing good, but it risks justifying things like eugenics. Once you accept that some lives shouldn’t be saved or born, you risk treating some people as worth less than others.
What limits population, is farmable land. You shouldn’t worry about the rest. Malthusianism has been disproven many times.
A world with 20 billion people is as good. Humanity will leave its cradle one day, and go to the stars.
A world with 1 billion of people would be less innovative, sicker. If you look at past times: low population has not guaranteed anything to be better.
Economic theory predicts more people actually will stimulate demand for services, innovation and more.
As always population mostly has been limited by human organisation, technology, and food. Not by else. A 20 billion world is wholly liveable, more innovative, with slightly taller skyscrappers.
You people need to learn more about economics. Humans are very creative at increasing life quality. My nearby shops now has a system locker to rent an electronic device 1 day that’s automated, that’s what economies of scale are.
I am not here to ask if Earth can have 20 billion people or not, I’m here to ask about the dilemma of saving lives might not always be good. If you want, you can up the number to 200 billion people and see that Earth can’t handle that number. At a point, you must say that saving more people is not a good thing, and it will just be a bad thing. And now comes the dilemma: if you say that saving people is not for the sake of saving people, you might be justifying murder (or preventing births) as “the most effective thing to do.”