Vasco Grilo🔸 comments on Announcing the Rethink Priorities Cross-Cause Fund

[Vasco Grilo🔸]

Hi Nick. Do you know about any public explanations of why indirect effects on macroarthropods like soil ants and termites are not included? I suspect you have in mind the comments below. However, they apply to plants, microorganisms, nematodes, and microarthropods, not to macroarthropods like soil ants and termites.

Laura Duffy said on 17 July 2025:

We didn’t do the welfare range calculations for plants, protists, nematodes, etc, because we don’t think the methodology is appropriate for organisms that lack a complex brain and/​or nervous system

Bob Fischer said on 28 July 2025:

1. It’s true that we don’t think you can take our methodology and extend it arbitrarily. We grant that it’s very difficult to draw a precise boundary. However, it’s standard to develop a model for a purpose and be wary about its application in a novel context. Very roughly, we take those novel contexts to be ones where the probability of sentience is extremely low. We acknowledge that we don’t have a precise cutoff for “extremely low,” as establishing such a cutoff would be a difficult research project in its own right. There are unavoidable judgment calls in this work.

[...]

3. We don’t think that the assumptions of our “mainline welfare ranges” imply anything about the welfare ranges of plants, nematodes, and microorganisms, as the models simply aren’t intended to be used the way you are using them. That’s why we aren’t replying to you about the welfare ranges of plants, nematodes, and microorganisms. We would need to do an independent project to form opinions on your questions. Right now, we don’t have the funding for that project.

Bob said on 21 November 2025:

On the macro-level issue of priorities, I’ve gathered some of my thoughts here.

From the doc linked above:

Second, I want to do good, not just good in expectation. So, as the probability of sentience drops, I become more wary. Insects are fairly close to my limit. Right now, we have some evidence for sentience in some insect orders, which I find reasonably compelling. However, it isn’t compelling primarily because it checks some number of boxes in Birch’s precautionary framework; instead, it’s compelling because of its breadth and richness. We have nothing like the evidence for sentience in Drosophila [small fruit fly] for mites, springtails, thrips, and the like. For that reason, we can respond to the stock objections to sentience in insects. We can’t do anything analogous for these smaller arthropods. (And recall that their brains are one or two orders of magnitude smaller than the brains of many insects. I doubt there’s a linear relationship between sentience and any such neurophysiological feature; at some point, I’m inclined to think that the probability falls off a cliff.)

As I commented above, I estimate the effects of chicken welfare campaigns on ants and termites are much larger than those on chickens for the sentience-adjusted welfare ranges presented in Bob’s book. For this not to hold, I think the sentience-adjusted welfare ranges of ants and termites would have to be much lower than that of black soldier flies (BSFs). I would be surprised if this was the case under the methodology of Bob’s book. Godfrey et al. (2021) estimated 90 k neurons for a desert ant, and 92.5 k for a fruit fly (“vinegar fly”), and “individual number of neurons”^0.188 explains pretty well the welfare ranges in Bob’s book, as illustrated below.

[NickLaing]

Thanks @Vasco Grilo🔸 . Yes I was thinking about all those comments I just forgot exactly which invertebrates they referred to. I suspect they will have a similar answer about any soil invertebrates but we will see!

[Vasco Grilo🔸]

I suspect they will have a similar answer about soil invertebrates

Nitpick. I think you meant “about any soil invertebrates” or “about soil macroarthropods”.