tl;dr: In The Precipice, Toby Ord argues that some disagreements about population ethics don’t substantially affect the case for prioritising existential risk reduction. I essentially agree with his conclusion, but I think one part of his argument is shaky/overstated.
This is a lightly edited version of some notes I wrote in early 2020. It’s less polished, substantive, and important than most top-level posts I write. This does not capture my full views on population ethics or The Precipice. (I really liked the book overall.)
Some of the more extreme approaches to this relatively new field of ‘population ethics’ imply that there is no reason to avoid extinction stemming from consideration of future generations—it just doesn’t matter whether these future people come into being or not. [But] all but the most implausible of these views agree with the immense importance of saving future generations from other kinds of existential catastrophe, such as the irrevocable collapse of civilization. Since most things that threaten extinction threaten such a collapse too, there is not much practical difference.
Some of the more extreme approaches to this relatively new field of ‘population ethics’ imply that there is no reason to avoid extinction stemming from consideration of future generations—it just doesn’t matter whether these future people come into being or not.
[But] all but the most implausible of these views agree with the immense importance of saving future generations from other kinds of existential catastrophe, such as the irrevocable collapse of civilization. Since most things that threaten extinction threaten such a collapse too, there is not much practical difference.
I agree that even many views on population ethics which would say it doesn’t matter whether future people get to come into being would agree that it’s at least somewhat important to save future generations from at least some kinds of non-extinction existential catastrophe. (It’s also the case that my preferred views on population ethics very strongly support prioritising existential risk reduction.)
But I think Ord overstates things here, perhaps considerably. There are three reasons I say this.
Reason 1: The size of the stakes matters. And even in person-affecting views where avoiding irrevocable collapse matters, it matters far less than in some non-person-affecting views.
People like Ord and I believe that existential risk reduction is not just important, but rather extremely important, and thus worth prioritising despite reasonable concerns about predictability and tractability. These beliefs are substantially influenced by the future’s potential scale, duration, and quality, if we manage to avoid catastrophe (see, e.g., Ord’s note 37 in chapter 8).
Ord deliberately moves away from relatively extreme / contrarian / counterintuitive versions of that sort of argument. For example, he argues that the probability of existential catastrophe in the coming century is not miniscule, and that there are a variety of reasons to believe particular interventions could reduce the risks.
But it would seem hard to argue that it’s just as easy to predictably cause a significant reduction in existential risks as to predictably cause a substantial improvement in near-term global health and development or animal welfare. And I don’t believe Ord tries to make that argument. So the potentially extreme stakes involved in existential risks still seem like an important part of his claims.
Let’s say we accept some view on population ethics in which we don’t care about the loss of value from things like extinction or not colonising the stars, but do care about the reduced quality of life of people who would exist in an irrevocable collapse scenario. Thus, as Ord suggests, we still acknowledge that there are some future-people-related reasons to reduce existential risks (rather than just other types of reasons, such as preventing death and suffering in the present generation or fulfilling duties to the past).
But those reasons would be about something like “the difference between the total/average quality of life that those people would have given irrevocable collapse and the total/average quality of life that the same people—or the same number of people, or something like that—would’ve had if not for the irrevocable collapse”. That will entail far smaller stakes than “the difference in the total amount of value (e.g., aggregate wellbeing, or achievement, or whatever) given irrevocable collapse and the total amount of value given no existential catastrophe (so we colonise the stars, or fulfil our potential in some other way”.
So I think that adopting that sort of view on population ethics would make a major practical difference. It wouldn’t render existential risk reduction valueless, but would substantially reduce its value, perhaps making it a lower priority than seemingly more predictable and tractable priorities such as near-term animal welfare.
Reason 2: In views which include the asymmetry principle, avoiding irrevocable collapse may not matter, as people in collapse scenarios may have net-positive lives.
In Ord’s appendix on population ethics, he notes that some people have argued for:
an asymmetry principle: that adding new lives of positive wellbeing doesn’t make an outcome better, but adding new lives with negative wellbeing does make it worse.
Views which include such that sort of asymmetry principle would think it matters to prevent futures with large numbers of lives of negative wellbeing. Such views may thus indeed support existential risk reduction, but with a focus on dystopian futures and/or s-risks rather than extinction risk. (I think that that’s what I’d support if my views on population ethics included that sort of asymmetry principle.)
But recall that Ord focuses on collapse rather than dystopia:
all but the most implausible of these views agree with the immense importance of saving future generations from other kinds of existential catastrophe, such as the irrevocable collapse of civilization. Since most things that threaten extinction threaten such a collapse too, there is not much practical difference.
I’d guess most of the lives in an irrevocable collapse scenario would be somewhere around neutral or somewhat positive wellbeing. (It does seem plausible that they’d tend to be of negative wellbeing, but also plausible that they’d be of similar or greater wellbeing levels than we currently have.)
Maybe Ord considers views which include the asymmetry principle to be among “the most implausible” of views on population ethics. But if so, that seems fairly contestable. And if not, then these views might actually not see preventing a sizeable portion of the possible irrevocable collapse scenarios as mattering at all. That would further reduce the extent to which those views would, overall, be inclined to prioritise existential risk reduction.
One could respond by saying “But couldn’t many things that threaten extinction also threaten the sort of scenarios these views would care about preventing, such as s-risks?” I think that that’s plausible, but the matter is a lot more complicated than in the case of irrevocable collapse. Here are a couple somewhat relevant posts:
How Would Catastrophic Risks Affect Prospects for Compromise?
The long-term significance of reducing global catastrophic risks
Reason 3: I’m very unsure whether most things which threaten extinction pose a similar risk of irrevocable collapse.
Irrevocable collapse would involve a very long period of neither going extinct nor fully recovering. But it seems plausible to me that, given a collapse, it’s extremely likely that we’d relatively quickly—e.g., within thousands of years—either go extinct or fully recover. (My views on this are fuzzy and confused. See also Bostrom, 2013, section 2.2.)
If that is the case, that would substantially reduce the harm the collapse represented from the perspective of views on population ethics which don’t care about extinction but would care about some collapse scenarios.
Ord does surround the passage quoted above with caveats, and he dedicates an appendix to the topic.
But I don’t think the caveats or appendix really address this specific point I’m making.
I’m merely critiquing this specific argument for why population ethics may not cast doubt on whether to prioritise existential risk reduction. I personally prioritise existential risk reduction, and think there are other strong arguments for doing so despite population ethics concerns.
E.g., I see something like a “total view” as very plausible, and I see greater issues with person-affecting views than with a “total view”.
E.g., certain approaches to moral uncertainty will suggest the total view should be pretty dominant if it’s at least seen as plausible (although some see this as problematic fanaticism).
You can see a list of all the things I’ve written that summarise, comment on, or take inspiration from parts of The Precipice here.