Hi Eitan. Thanks for sharing. I am enthusiastic about this initiative.

Its impact is more direct — same animals, better lives. Many animal-welfare interventions can be contested based on their indirect or secondary effects, such as how a diet shift ripples through wild-animal populations, say, or whether a reform just moves production elsewhere. Welfare Tech is comparatively straightforward: it improves the lives of animals already being farmed anyway.

I think interventions improving the lives of farmed animals may increase or decrease the welfare of soil invertebrates much more than they increase the welfare of farmed animals.

I see no escape from the uncertainty about the effects on soil invertebrates if one wants to increase welfare while accounting for all animals. I am not aware of any intervention supported by impact-focussed funders with effects on soil invertebrates robustly smaller than those on the target beneficiaries. Not saving human lives, not decreasing the consumption of animal foods or ingredients, not replacing fast with slower growth chicken, not replacing layers in battery cages with ones in cage-free aviaries or barns, not replacing standard with bird-safe glass, not replacing rodenticide with fertility control bait, and not even electrically stunning farmed shrimps.

It’s cost-effective, and the economics compound. Take shrimp stunners, estimated to help on the order of 1,400–1,500 shrimp per dollar per year.⁵ On a welfare-adjusted basis, some analyses (admittedly controversial) found it arguably ~100× more cost-effective than cage-free corporate campaigns, which are estimated at 9–120 chicken-years per dollar. Those multiples lean on moral-weight assumptions for shrimp and pain during death; but even discounted, they’re remarkable.

5. Vasco Grilo, “Cost-effectiveness of Shrimp Welfare Project’s Humane Slaughter Initiative,” EA Forum, 6 Oct 2024: forum.effectivealtruism.org/posts/EbQysXxofbSqkbAiT; and the 2025 ACE review of SWP. The ≈100× multiple relies on Rethink Priorities’ median shrimp welfare range (~3% of a human’s).

It would be better to argue for high cost-effectiveness comparing interventions targeting similar species (with one intervention involving welfare tech)? Otherwise, the results of the comparisons will be influenced a lot by the uncertainty in welfare comparisons across species. I estimated the Shrimp Welfare Project’s (SWP’s) Humane Slaughter Initiative (HSI) has increased the welfare of shrimps 139 times as cost-effectively as cage-free egg corporate campaigns increase the welfare of chickens. However, for sentience-adjusted welfare ranges proportional to "individual number of neurons"^"exponent", and "exponent" from 0 to 2, which covers the best guesses that I consider reasonable, I calculate that HSI has increased the welfare of shrimps 2.26*10^-4 to 1.49 k times as cost-effectively as cage-free egg corporate campaigns. In other words, I have practically no idea about which interventions increases the welfare of their target beneficiries more cost-effectively. Below is a graph with the results for "exponent" from 0 to 2.

Hello. Thanks for the comment. I am open to bets against short timelines for transformative AI (TAI), or what they supposedly imply, up to 10 k$. Do you see any that we could make?

Hi Aidan. Thanks for the update. This looks like a great analysis, as did the ones for 2020-2022, and 2023-2024.

We note that our multiplier will face pressure from the denominator in coming years. Our 2026 budget of 2.1M, reflecting planned investments in growth. Maintaining or improving our multiplier will require continued growth in the value we generate — through both new pledge acquisition and the realised donations of existing pledgers. We view the 2025 result as an encouraging signal that our strategy is producing returns, but sustaining this as we scale will require ongoing attention to both the volume and quality of our pledge work.

The increased spending in 2026 will be useful to get a better sense of the marginal multiplier. The multiplier on the total spending over 2026 being significantly lower than 7 (the multiplier on the total spending over 2025) would signal a marginal multiplier in 2026 significantly lower than 7.

Can you provide some specific examples, and I'll reconsider

I mostly had this section in mind. I think the positive correlation between hedonic welfare and reported seemingly honest preferences in humans provides some weak evidence that there is such a correlation for AIs. There are some similarities between humans and AIs. 

I'm not sure if we 'agree' here, or at least that's not the point I was making. I was accepting that AI models (either the information flow itself, or the physical electron flows or something) might indeed "have" or generate consciousness and welfare.

Right. However, I think AI welfare being difficult to measure conditional on sentience tends to imply that assessing AI sentience is also difficult. So I would prioritise decreasing uncertainty about this too.

What I meant was that even if the AI is making a confident statement that it is in pain, and it is not deliberately lying, it doesn't mean that it actually knows the answer to 'is it (or is anything in it's system) in pain'.

So the 'even if' was setting off a contrast between 'not having a access to the answer' and 'making a confident statement'.

Makes sense.

In addition, in allometry, "the study of the relationship of body size to shape,^[1] anatomy, physiology and behaviour", "The relationship between the two measured quantities is often expressed as a power law equation (allometric equation)".

From the book "Scale: The Universal Laws of Growth, Innovation, Sustainability, and the Pace of Life in Organisms, Cities, Economies, and Companies" by Geoffrey West:

This scaling law for metabolic rate [this one], known as Kleiber’s law after the biologist who first articulated it, is valid across almost all taxonomic groups, including mammals, birds, fish, crustacea, bacteria, plants, and cells [see this section of my linkpost for further discussion]. Even more impressive, however, is that similar scaling laws hold for essentially all physiological quantities and life-history events, including growth rate, heart rate, evolutionary rate, genome length, mitochondrial density, gray matter in the brain, life span, the height of trees and even the number of their leaves. Furthermore, when plotted logarithmically this dizzying array of scaling laws all look like Figure 1 and therefore have the same mathematical structure. They are all “power laws” and are typically governed by an exponent (the slope of the graph), which is a simple multiple of ¼, the classic example being the ¾ for metabolic rate. So, for example, if the size of a mammal is doubled, its heart rate decreases by about 25 percent. The number 4 therefore plays a fundamental and almost magically universal role in all of life.13

Footnote 13:

There are several excellent texts summarizing the various allometric scaling laws in biology. Among them are: W. A. Calder, Size, Function and Life History (Cambridge, MA: Harvard University Press, 1984); E. L. Charnov, Life History Invariants (Oxford, UK: Oxford University Press, 1993); T. A. McMahon and J. T. Bonner, On Size and Life (New York: Scientific American Library, 1983); R. H. Peters, The Ecological Implications of Body Size (Cambridge, UK: Cambridge University Press, 1986); K. Schmidt-Nielsen, Why Is Animal Size So Important? (Cambridge, UK: Cambridge University Press, 1984).

Hello. Thanks for sharing. Yesterday I created a WhatsApp group for people interested in effective altruism in Porto. It is under the WhatsApp community Effective Altruism and Rationality Portugal, where I just shared the post above.

You may want to add deadlines for submitting the application forms, and consider having a single form for all applications (where people can specify the location they are interested in).

I am very uncertain about whether decreasing the number of farmed animals increases or decreases animal welfare (in expectation) due to potentially dominant effects on soil invertebrates. In addition, I worry decreasing the number of farmed animals may prevent some from having positive lives.

Hi David. Great post. I broadly agree. Relatedly, readers may be interested in the post AI Welfare Is (Frankfurtian) Bullshit.

I sometimes felt you were implying "no evidence" when I thought something closer to "very weak evidence" would be more appropriate. However, in practice, I would agree the focus should overwhelmingly be on decreasing the uncertainty about the extent to which AI models have welfare, and how to measure it.

I don't find this convincing. (NB: I'm still working on this response.) Even if the talker has no access to the valenced consciousness, it's model may simply lead it to a confident and wrong answer about this.

Did you mean "If" instead of "Even if"?

Wha tmight

Nitpick. "What might".

Hi Aïda. That makes sense. However, I think the reasons you mentioned sometimes play against increasing animal welfare. Poorer welfare standards tend to have a lower carbon and land footprint.

Hi Phalox. Thanks for the comment. You may be interested in my post "Insecticide-treated nets [ITNs] significantly harm mosquitoes, but one can easily offset this?", where I compared the effects of ITNs on humans and mosquitoes.

Relatedly, saving human lives also affects soil invertebrates due to resulting in more agricultural land to feed the people who are saved, and I think the effects on soil invertebrates may be much larger or smaller than the benefits to humans. I calculate that GiveWell's top charities change the living time of soil invertebrates by 539 M animal-years per $, and that of soil arthropods by 10.8 M animal-years per $. As illustrated in the graph below, I estimate such charities may change the welfare of soil invertebrates much more or less than they they benefit humans. The title of graph says "Increase in the welfare", not "Change in the welfare", because I assumed expanding agricultural land increases the welfare of soil invertebrates, but I am very uncertain about this. The estimates below suppose welfare per fully-healthy-animal-year is proportional to "individual number of neurons"^"exponent". An exponent between 0 and 2 covers the best guesses that I consider reasonable.