Strongly agree about "the evidential situation with respect to comparing the individual welfare per animal-year"! I've always taken the numbers from the MWP much less seriously than others. I see that work as one part of a large picture, depending heavily on other arguments.

And thank you for voting for Arthropoda!

Thanks, Nick. A few quick thoughts:
 

1. It's reasonable to think there are important differences between at least some insects and some of the smaller organisms under discussion on the Forum, like nematodes. See, e.g., this new paper by Klein and Barron.
2. I don't necessarily want to give extra weight to net harm, as Michael suggested. My primary concern is to avoid getting mugged. Some people think caring about insects already counts as getting mugged. I take that concern seriously, but don't think it carries the day.
3. I'm generally skeptical of Forum-style EV maximization, which involves a lot of hastily-built models with outputs that are highly sensitive to speculative inputs. When I push back against EV maximization, I'm really pushing back against EV maximization as practiced around here, not as the in-principle correct account of decision-making under uncertainty. And when I say that I'm into doing good vs. doing good in expectation, that's a way of insisting, "I am not going to let highly contentious debates in decision theory and normative ethics, which we will never settle and on which we will all change our minds a thousand times if we're being intellectually honest, derail me from doing the good that's in front of me." You can disagree with me about whether the "good" in front of me is actually good. But as this post argues, I'm not as far from common sense as some might think.
4. FWIW, my general orientation to most of the debates about these kinds of theoretical issues is that they should nudge your thinking but not drive it. What should drive your thinking is just: "Suffering is bad. Do something about it." So, yes, the numbers count. Yes, update your strategy based on the odds of making a difference. Yes, care about the counterfactual and, all else equal, put your efforts in the places that others ignore. But for most people in most circumstances, they should look at their opportunity set, choose the best thing they think they can sweat and bleed over for years, and then get to work. Don't worry too much about whether you've chosen the optimal cause, whether you're vulnerable to complex cluelessness, or whether one of your several stated reasons for action might lead to paralysis, because the consensus on all these issues will change 300 times over the course of a few years.

Thanks, Michael. I'm quite sympathetic to the idea of bracketing!

Lastly, this article is good. The possibility the they’re right is one of the things that makes me inclined to see insects as the limit case. 

Thanks, all. Let me add something that may help clarify why we're always at loggerheads. I’m not actually thinking about these questions in probabilistic terms at all. In my view, the evidential situation for most arthropods is so sparse that I don’t actually believe we’re in a position to assign meaningful probabilities of sentience—even extremely rough ones. We’re squarely in the domain of the precautionary, not the probabilistic. When the evidence is this patchy and the mechanisms this poorly understood, numerical probability assignments feel more like artifacts of modeling choices than reflections of the world. So, when I talk about “robustness,” I’m not covertly appealing to narrower or wider probability distributions; I’m saying that the entire framework of attaching numbers to these uncertainties feels inappropriate.

This is one of several reasons why focusing on well-studied insects makes sense to me. It’s not that I think BSF larvae are 10× or 100× more likely to be sentient than springtails. It’s that we have a type of evidence for some insects—convergent behavioral, physiological, and neuroanatomical findings—that simply doesn’t exist at all for mites, springtails, and nematodes. And without that evidential base, I'm wary of using a first-pass model to set priorities. Expected value becomes extremely fragile under those conditions, as the inputs aren’t grounded: they’re guesses stacked on guesses.

So the way I think about prioritization has less to do with estimated probabilities and more to do with where precautionary reasoning can actually get traction. Work on farmed and research arthropods produces immediate welfare improvements, helps develop welfare indicators, and builds the scientific ecosystem we’ll need if we ever hope to understand smaller arthropods. That’s a much more stable basis for action than trying to set priorities via BOTECs.

Anyway, we'll just have to agree to disagree, as we just keep running up against the same issues over and over!

I'm sorry that I don't have time to respond to all your questions, Vasco. The short version, though, is that I also want robustness in the case for sentience, so I'm much less inclined to make the kinds of extrapolations you're suggesting here. I have the same view about our moral weight work: I put very little stock in any specific numbers, as I think that plausible moral weights will be defensible from several angles, each of which will suggest somewhat different estimates, with no obvious right way to aggregate them. (Again, there's that skepticism about expected value!)

Arthropoda is a 501(c)(3). As this thread indicates, Mal Graham and I run the organization. We keep a lean profile because many science funders keep a lean profile. I realize that it isn't optimal for fundraising, but I think it's normal enough from the perspective of our grantees. If you'd like to discuss further, happy to chat.

I agree with Mal about Arthropoda being a good bet for this work. RP would be good too. On the macro-level issue of priorities, I've gathered some of my thoughts here.

Finally, I'll say publicly what I've said privately: thank you for supporting Arthropoda. It means a lot to me that you donated.

Thanks, Vasco! Abraham's post covers many more farmed insects than BSF and mealworms. (For instance, the lower end of his farmed cochineal estimate is 4.6T deaths annually.) When you include those other species, I think the "rounding error" claim becomes more plausible. (Sorry not to be clear in the post: I probably gave the impression that I was only thinking of the standard "insects as food and feed" species.)

In the interest of clarity, I've updated the original post in response to @Hugh P's helpful question.