Concerning the merits of lexical NU, I just don’t see how it’s plausible to postulate a sharp value discontinuity along the suffering continuum. As discussed many times in the past, one can construct a series of pairwise comparisons involving painful experiences that differ only negligibly in their intensity.
So, I agree that sharp values in discontinuity are not a great aspect for a moral system to have but consider
We put suffering and happiness on the same scale to reflect how they look in our utility functions. But really, there are lots of kinds of suffering that are qualitatively different. While we can do it sometimes, I’m not sure if we are always capable of making direct, optimized comparisons of qualitatively different experiences
We don’t actually have a great definition of what suffering is and, if we model it in terms of preferences, it bottoms out. AKA, there’s a point in suffering when I could imagine myself saying something like “This is the worst thing ever; get me out of here no matter what.” Our subjective experience of suffering and our actual ability to report it breaks down
It’s also super hard to really understand what it’s like to be in edge-case extreme suffering situations without actually being in one, and most people haven’t. Without that (and even potentially with it), trying to model ourselves in extreme suffering would require us to separate logical fallacies we would make in such a situation with our de-facto utility function. From an AI alignment perspective, this is hard.
If you’re an agent and you can’t reason about how bad something is while you’re in a situation and you don’t have a mental model of what that situation is like, getting into that kind of situation is a really bad idea. This isn’t just instrumentally inconvenient; it’s inconvenient in a “you know you’re suffering really badly but you can only model your experience as arbitrarily bad”
Even if we agree that our utility functions shouldn’t have strange discontinuities in suffering, there may still be a strange and discontinuous landscape of levels of suffering we can experience in the landscape of world-states. This is not directly incompatible with any kind of utilitarianism but it makes arguments along the lines of “imagine that we make this suffering just slightly, and virtually unnoticeably, worse” kind of weird. Especially in the context of extreme experiences that exist in a landscape we don’t fully understand and especially in a landscape where the above points apply
I’m a moral anti-realist. There’s no strict reason why we can’t have weird dicontinuities in our utility functions if that’s what we actually have. The “you wouldn’t want to trade a dramatic amount of resources to move from one state of suffering to an only infinitesimally worse one” makes sense but, per the above, we need to be careful about what that actually implies about how suffering works
This is all to say that suffering is really complicated and disentangling concerns about how utility functions and suffering work in reality from what logically makes sense is not an easy task. And I think part of the reason people are suffering-focused is because of these general problems. I’m still agnostic on whether something like negative lexical threshold utilitarianism is actually true but the point is that, in light of the above things, I don’t think that weird discontinuities is enough to dismiss it from the zone of plausibility.
This is an overgeneralization of suffering-focused views. You can believe in Lexical Threshold Negative Utilitarianism (ie there is some point at which suffering is bad enough where it becomes infinitely worse than less bad experiences) where the threshold itself is applied at the person-level rather than the aggregate suffering over all beings level. In this case, many people experiencing mild suffering is trivially better than a smaller number of people experiencing extreme suffering. Not sure if I completely buy into this kind of philosophy but I think it’s plausible.