Sorry, you did say this in the other thread as well and I should have made that clear in my comment originally. Have now edited.

Fascinating discussion between the two of you here, thanks.

I have one comment: I don't think their welfare being exactly 0 should have negligible probability. If we consider an animal like the soil nematode, I think there should be a significant probability assigned to the possibility that they are not sentient, unless I'm missing something?

Outsourcing the welfare estimates to Gemini seems like a risky move to me. It's a key part of the whole analysis, but is an extremely challenging question to begin answering. What's the reason to expect Gemini to be able to do a good job of this, given the blind spots we know current AI models still have?

I tried pasting your prompt into ChatGPT, with research mode, and the 3 value estimates it gave were all positive, rather than negative: https://chatgpt.com/share/683f34e8-8088-8006-8ba4-b719d025ac45

If I'm understanding right, this would flip all your conclusions on their head, and instead of trying to eliminate wild animal habitats, the top priority would be to increase them?

Such extreme sensitivity to highly uncertain quantities strikes me as a strong reductio ad absurdum argument against this approach to decision making on this kind of question. Otherwise we find ourselves oscillating wildly between "destroy all nature" and "destroy all humans" on the basis of each piece of new information, never being especially confident in either.

I like Bayesianism and expected value maximization as a framework for decision making under uncertainty, but when considering situations with enormous amounts of value described by extremely speculative probability estimates, I think we probably need to approach things differently (or at least adapt our priors so as to be less sensitive to these kind of problems). Something like Holden Karnofsky's approach here (which Anthony DiGiovanni shared with me on a recent post on insect suffering).

Edit: Anthony DiGiovanni doesn't actually endorse Holden Karnofsky's approach (see Anthony's comment below).

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).

If the claim is that every moral theory is equivalent to 'rule consequentialism', maybe you have more of a case. But 'act consequentialism' is very distinct I think.

I disagree, I think the difference is substantive.

A utilitarian form of consequentialism might tell Alice to save the drowning child in front of her, while it tells Bob to donate to the AMF, but despite acting differently, both Alice and Bob are pursuing the same ultimate agent-neutral aim: to maximize welfare. The agent-relative 'aims' of saving the child or making the donation are merely instrumental aims. They exist only as a means to an end, the end being the fundamental agent-neutral aim that both both Alice and Bob have in common.

This might sound like semantics, but I think the difference can be made clearer by considering situations involving conflict.

Suppose that Alice and Bob are in complete agreement about what the correct theory of ethics is. They are also in complete agreement on every question of fact (and wherever they are uncertain about a question of fact, they are in agreement on how to model this uncertainty e.g. maybe they are Bayesians with identical subjective probabilities for every concievable proposition). This does not imply that they will act identically, because they may still have different capacities. As you point out, Alice might have greater capacity to help the child drowning in front of her than Bob does, and so any sensible theory will tell her to do that, instead of Bob. But still, there is an important difference between the case where they are consequentialists and the case where they are not.

If Alice and Bob subscribe to a consequentialist theory of ethics, then there can be no conflict between them. If Alice realises that saving the child is going to interfere with Bob's pursuit of donating, or vice versa, then they should be able to figure this conflict out between them and come up with an agreed way of coordinating to achieve the best outcome, as judged by their common shared ultimate aims. This is possible because their shared aims are agent-neutral.

But if Alice and Bob subscribe to a non-consequentialist theory (e.g. one that says we should give priority to our own family) then it is still possible for them to end up in conflict with one another, despite being in complete agreement on the answer to every normative and empirical question. For example, they might each pursue an outcome which is best for their respective families, and this may involve competing over the same resources.

If i recall correctly, in Reasons+Persons, Parfit examines this difference around conflicts in detail. He considers the particular case of prioners-dilemma style conflicts (where each party acting in their own interests leaves them worse off than if they had cooperated) and claims this gives a decisive argument against non-consequentialist theories which do not at least switch to more agent-neutral recommendations in such circumstances (and he argues this includes 'common-sense morality').

I really appreciate you taking the time to write such a detailed reply to my comment, thank you! And for sharing additional reading material on these questions. What you say makes a lot of sense. I think this research is really important and fascinating work, and I'm excited to hear about what progress you can make.

I understand you might not have time to engage in further back-and-forth on this, but I just wanted to elaborate a bit on the one part of my comment that I think is maybe not directly answered by your reply. This is the issue around how we can compare the utility functions of different individuals, even in principle.

Suppose we know everything there is to know about how the brain of a fly works. We can figure out what they are thinking, and how these thoughts impact their behaviour. Maybe you are right that one day we might be able to infer from this that 'fly experience A' is roughly 10x more painful than 'fly experience B' (based purely on how it influences their choices among trade-offs - without relying on any assumptions around signal strength). But once we have determined the utility function for each separate individual (up to an undetermined constant factor), this still leaves open the problem of how to compare utility functions between different individuals, e.g. how to compare 'fly experience A' to 'human experience C'. The vN-M approach does not tell you how to do that.

With humans, you can fairly easily get around this limitation in practice. You just need to find one reference experience that you expect to be similar for everyone (which could be as simple as something like stubbing your toe) and then with that one bridge between individual utility functions established, a standard 'unit' of utility, all other comparisons follow. I can even imagine doing something like this to compare the welfare of humans with other non-human mammals or birds.

But by the time we consider insects, I find it hard to imagine how we would approach picking this 'reference' experience that will allow us to do the inter-species welfare comparisons that we want to do. I'm still not sure I'm convinced that the methods outlined here will ultimately enable us to do that. It's not just that the 'signal strength' assumption is 'unproven', it is that I am struggling to wrap my head around what a proof of that assumption would even look like. The correlation between pain intensity and signal strength in vertebrates presumably is based on within-individual comparisons, not between-individual comparisons, and assuming that a correlation in the first-type of comparison implies a correlation in the other still seems like a big extrapolation to me.

Haha, ok, fair enough, I was not expecting that response!

Your solution (and Karnofsky's) sound very interesting to me. But I'll need to read both links in more depth to properly wrap my head around it.

A few questions though:

• Karnofsky's worked example for applying their multi-model technique leads with: "does this action deviate greatly from 'normality?'"  Why is this not just a more formalized version of the appeal to absurdity heuristic?
• Not everyone is a galaxy-brain philosopher who can come up with complex blogposts like those to explain why giving their wallet to a Pascal mugger is wrong, yet everyone gets the correct (presumably) answer to this thought experiment anyway. And I think most are getting there by using some kind of absurdity heuristic? I think that should count in favour of the usefulness of the appeal to absurdity heuristic! Really feels like there's a good galaxy-brain meme in this. (I get I'm rolling back here on my early suggestion that we could abandon the absurdity heuristic as soon as just one person could come up with a solution to the problem of pascal's mugger).
• Back to the actual subject of this post: Do you think the approach outlined in your 2 links could be used as an argument against the overwhelming importance of insect suffering, at least for someone who was extremely uncertain about the likelihood of insect sentience or its intensity?

Would you give your wallet to a pascal mugger?

If yes: Guess what? I am a sorcerer from a parallel universe who has the ability to conjure arbitrary numbers of sentient beings into existence at will, and subject them to extreme torture. You tell me how unlikely you think this claim is. I will then threaten 10x the reciprocal of that number, unless you give me £100. I can send you my details and we can arrange the transfer.

If no: How do you explain this other than by an appeal to absurdity? I would love to know the solution to this problem.

Unless or until we have a better solution to this problem than "that's absurd", then I think we have to allow appeals to absurdity, especially when used against an argument that bears some resemblance to this pascal mugger example, at least superficially.