Debate: organisations using Rethink Priorities’ mainline welfare ranges should consider effects on soil nematodes, mites, and springtails, or at least be transparent about their reasons for neglecting them?
Effects on soil nematodes should not be neglected just because they may be beneficial or harmful. Mathematically speaking, “number which is certain to be barely positive” + “number which can be very negative, barely negative, barely positive, or very positive” = “number which can be very negative, barely negative, barely positive, or very positive”, which does not have to be barely positive in expectation. I would only disregard the effects on soil animals if I considered them much smaller in expectation than those being considered.
Estimates of the expected effects on soil nematodes, mites, and springtails cannot be taken literally, but should still be considered. One should update less on uncertain evidence, but more given an uncertain prior.
Many argue effects on soil nematodes, mites, and springtails should only be considered once society cares much more about animals than now. I suspect this results from implicitly supposing that helping animals more inside society’s moral circle, like farmed vertebrates, is more cost-effective. In contrast, I recommend supporting the interventions which at the margin increase welfare the most per $, even if to increase the welfare of animals which are highly neglected in society.
I think organisations using RP’s mainline welfare ranges should consider effects on soil nematodes, mites, and springtails
I think organisations using RP’s mainline welfare ranges, at least AIM, ACE, AWF, and RP, should consider effects on soil nematodes, mites, and springtails. If they are not planning to consider these effects, I think they should explain why not for reasoning transparency. I believe these are the driver of the overall effects of the vast majority of interventions. I estimate the following based on welfare ranges for those soil animals derived from RP’s mainline welfare ranges:
Cage-free corporate campaigns benefit those soil animals 28.2 times as much as they benefit chickens.
Broiler welfare corporate campaigns benefit those soil animals 444 times as much as they benefit chickens.
Veganuary in 2024 harmed those soil nematodes 3.58 k times as much as they benefited farmed animals.
School Plates in 2023 harmed those soil nematodes 5.42 k times as much as they benefited farmed animals.
GiveWell’s top charities benefit those soil animals 87.6 k times as much as they benefit humans.
Buying beef benefits those soil animals 1.82 M times as much as it benefits cows.
I also estimate feed crops replacing temperate grasslands, savannas, and shrublands increases the welfare of soil nematodes, mites, and springtails 9.39 (shrimp) to 11.7 M (dairy milk) times as much as it changes the welfare of directly affected animals.
I believe any organisation aiming to increase animal welfare should consider the effects on soil animals. I am focussing on the ones using RP’s mainline welfare ranges given the apparent contradiction between this, and neglecting effects on soil animals. In addition, neglecting effects on soil animals increases the probability of causing harm, so organisations which intrinsically value decreasing this, instead of just maximising expected impact, have an additional reason to consider them.
AIM may be the most open to considering these. Joey Savoie, AIM’s CEO, said on 15 May 2023 they “consider cross-cause effects in all the interventions we consider/recommend, including possible animal effects and WAS [wild animal suffering] effects”. However, none of AIM’s public reports covers effects on wild animal welfare of interventions targeting humans, or farmed animals.
ACE commented on 25 June 2025 they “intend to publish a blog post on the consequences of farmed animal welfare interventions for wild animals, after the busy work of charity evaluations is wrapped up for the season”.
Effects on soil nematodes should not be neglected just because they are unlikely to be sentient
I suspect many are only willing to account for effects on beings which are sufficiently likely to be sentient, even if the effects on them are very large in expectation due to them being very numerous. It is as if probabilities of sentience below a minimum arbitrary threshold are rounded to 0. Even Peter Singer seems to have too much binary thinking about which animals are considered. Peter seemingly advocates much more for vertebrates than invertebrates, and said in 2023 that “a reasonable place to draw the line is to say that there are some invertebrates that can feel pain”. I do not think one should be drawing lines defining a moral circle. Sentience, and welfare per animal-year are probabilistic, and this has to be multiplied by the number of individuals to get their total welfare. Invertebrates are less likely to be sentient, and have a welfare per animal-year closer to 0 than vertebrates, but there are many more of them. Rounding to 0 a probability of sentience, or welfare per animal-year close to 0 introduces an infinite amount of scope insensitivity. Regardless of the number of beings affected, the change in their welfare will be estimated to be exactly 0.
Furthermore, the probability of sentience of soil nematodes, mites, and springtails is not anything close to Pascalianly low. RP got a probability of sentience for nematodes, which have the least neurons among those soil animals, of 6.8 % under their preferred “#1 High-Value Proxies Model”, and it only ranged from 6.8 % to 6.9 % across the 5 models they considered, although I assume these are far from independent given the proximity of the estimates. I suspect the actual probability of sentience of nematodes is higher. In RP’s words, “Assigning proxies labeled “Unknown” zero probability of being present is certainly leading to underestimates of the welfare ranges and probabilities of sentience [all else equal]”. The probability of dying in a car crash is around 2.70*10^-9 per km (= 10^-6/370), and many people still consider it reasonable to fasten seat belts for increased safety on short trips, even if they would prefer it to be optional.
Effects on soil nematodes should not be neglected just because they may be beneficial or harmful
I expect the interventions I mentioned above to benefit soil nematodes for my best guess that they decrease their population, and that soil nematodes have negative lives. Nevertheless, I got a probability for this of 58.7 %, so I am uncertain about whether the effects on soil nematodes are beneficial or harmful. However, they should not be neglected just because of this. Consider an intervention aiming to decrease the consumption of animal-based foods which:
Increases the welfare of farmed animals, the target beneficiaries, by 1 QALY with 100 % probability.
Decreases the welfare of soil nematodes by 1 kQALY with 30 % probability, and by 0.001 QALY with 30 % probability.
Increases the welfare of soil nematodes by 0.001 QALY with 20 % probability, and by 1 kQALY with 20 % probability.
There is lots of uncertainty about whether the effects on soil nematodes are very negative, barely negative, barely positive, or very positive, but I would not neglect them. They decrease welfare by 100 QALY (= 0.3*(1*10^3 + 0.001) − 0.2*(1*10^3 + 0.001)) in expectation, and therefore the intervention decreases welfare by 99.0 QALY (= 100 − 1*1) in expectation, thus being harmful.
You may well disagree with my numbers above. However, mathematically speaking, “number which is certain to be barely positive” + “number which can be very negative, barely negative, barely positive, or very positive” = “number which can be very negative, barely negative, barely positive, or very positive”, which does not have to be barely positive in expectation. I would only disregard the effects on soil animals if I considered them much smaller in expectation than those being considered.
Estimates of the expected effects on soil nematodes, mites, and springtails cannot be taken literally, but should still be considered
Joey said the following about my estimates of the effects on soil nematodes, mites, and springtails.
I also think about evidence as described in that post from Holden Karnofsky. Here is the summary of it I published in April 2022. I agree on not updating all the way from one’s prior estimate of the expected value to the new one, and on updating less on more uncertain evidence. Yet, as implied by inverse-variance weightingused in meta-analyses, one should also update more given a more uncertain prior. I believe any reasonable prior estimate of the effects on soil nematodes, mites, and springtails will be highly uncertain. So I maintain estimates of the expected effects like mine should still be considered.
I suspect many are misinterpreting Holden’s post due to conflating the prior about the effects on humans with the prior about the effects on all potentially sentient beings. Holden rejects impartiality, which means 1 unit of welfare is always worth the same, even in principle, so he can consider a more certain prior which neglects some effects. I would say one should fully endorse impartiality at least in principle, and therefore consider the prior about the effects on all potentially sentient beings. This prior is much more uncertain than the one about the effects on humans, thus enabling much larger updates towards new estimates of the expected effects on soil nematodes, mites, and springtails.
Effects on soil nematodes, mites, and springtails should be considered even if they are very neglected in society
Many argue effects on soil nematodes, mites, and springtails should only be considered once society cares much more about animals than now. I suspect this results from implicitly supposing that helping animals more inside society’s moral circle, like farmed vertebrates, is more cost-effective. In contrast, I recommend supporting the interventions which at the margin increase welfare the most per $, even if to increase the welfare of animals which are highly neglected in society.
Moreover, some of the most cost-effective ways of increasing human welfare, like GiveWell’s top charities, target people in low income countries, and I estimate they are also among the most cost-effective interventions accounting for effects on soil nematodes, mites, and springtails. My best guess is that these have negative lives, and decreasing human mortality without decreasing food consumption increases cropland, thus decreasing the population of those animals. Humans in low income countries are more inside society’s moral circle than animals, but are still widely neglected. So I wonder what would be the case for prioritising less neglected animals over humans in low income countries. Likewise, I would like to know why the same arguments do not imply prioritising farmed vertebrates over farmed invertebrates, or pets over farmed vertebrates. I suspect many bring up cost-effective moral circle expansion as a justification for why helping their target animals is very cost-effective even accounting for all animals although this did not factor into their initial reasons.
Acknowledgements
Thanks to Vicky Cox for feedback on the draft, and to Zuzana Sperlova for confirming the cost-effectiveness analyses ACE will do this year will rely on RP’s mainline welfare ranges. I listed the names alphabetically. The views expressed in the post are mine.
Debate: organisations using Rethink Priorities’ mainline welfare ranges should consider effects on soil nematodes, mites, and springtails, or at least be transparent about their reasons for neglecting them?
Summary
I think organisations using Rethink Priorities’s (RP’s) mainline welfare ranges, at least Ambitious Impact (AIM), Animal Charity Evaluators (ACE), the Animal Welfare Fund (AWF), and RP, should consider effects on soil nematodes, mites, and springtails. I believe these are the driver of the overall effects of the vast majority of interventions.
Effects on soil nematodes should not be neglected just because they may be beneficial or harmful. Mathematically speaking, “number which is certain to be barely positive” + “number which can be very negative, barely negative, barely positive, or very positive” = “number which can be very negative, barely negative, barely positive, or very positive”, which does not have to be barely positive in expectation. I would only disregard the effects on soil animals if I considered them much smaller in expectation than those being considered.
Estimates of the expected effects on soil nematodes, mites, and springtails cannot be taken literally, but should still be considered. One should update less on uncertain evidence, but more given an uncertain prior.
Many argue effects on soil nematodes, mites, and springtails should only be considered once society cares much more about animals than now. I suspect this results from implicitly supposing that helping animals more inside society’s moral circle, like farmed vertebrates, is more cost-effective. In contrast, I recommend supporting the interventions which at the margin increase welfare the most per $, even if to increase the welfare of animals which are highly neglected in society.
I think organisations using RP’s mainline welfare ranges should consider effects on soil nematodes, mites, and springtails
I think organisations using RP’s mainline welfare ranges, at least AIM, ACE, AWF, and RP, should consider effects on soil nematodes, mites, and springtails. If they are not planning to consider these effects, I think they should explain why not for reasoning transparency. I believe these are the driver of the overall effects of the vast majority of interventions. I estimate the following based on welfare ranges for those soil animals derived from RP’s mainline welfare ranges:
Cage-free corporate campaigns benefit those soil animals 28.2 times as much as they benefit chickens.
Broiler welfare corporate campaigns benefit those soil animals 444 times as much as they benefit chickens.
Veganuary in 2024 harmed those soil nematodes 3.58 k times as much as they benefited farmed animals.
School Plates in 2023 harmed those soil nematodes 5.42 k times as much as they benefited farmed animals.
GiveWell’s top charities benefit those soil animals 87.6 k times as much as they benefit humans.
Buying beef benefits those soil animals 1.82 M times as much as it benefits cows.
I also estimate feed crops replacing temperate grasslands, savannas, and shrublands increases the welfare of soil nematodes, mites, and springtails 9.39 (shrimp) to 11.7 M (dairy milk) times as much as it changes the welfare of directly affected animals.
I believe any organisation aiming to increase animal welfare should consider the effects on soil animals. I am focussing on the ones using RP’s mainline welfare ranges given the apparent contradiction between this, and neglecting effects on soil animals. In addition, neglecting effects on soil animals increases the probability of causing harm, so organisations which intrinsically value decreasing this, instead of just maximising expected impact, have an additional reason to consider them.
AIM may be the most open to considering these. Joey Savoie, AIM’s CEO, said on 15 May 2023 they “consider cross-cause effects in all the interventions we consider/recommend, including possible animal effects and WAS [wild animal suffering] effects”. However, none of AIM’s public reports covers effects on wild animal welfare of interventions targeting humans, or farmed animals.
ACE commented on 25 June 2025 they “intend to publish a blog post on the consequences of farmed animal welfare interventions for wild animals, after the busy work of charity evaluations is wrapped up for the season”.
Effects on soil nematodes should not be neglected just because they are unlikely to be sentient
I suspect many are only willing to account for effects on beings which are sufficiently likely to be sentient, even if the effects on them are very large in expectation due to them being very numerous. It is as if probabilities of sentience below a minimum arbitrary threshold are rounded to 0. Even Peter Singer seems to have too much binary thinking about which animals are considered. Peter seemingly advocates much more for vertebrates than invertebrates, and said in 2023 that “a reasonable place to draw the line is to say that there are some invertebrates that can feel pain”. I do not think one should be drawing lines defining a moral circle. Sentience, and welfare per animal-year are probabilistic, and this has to be multiplied by the number of individuals to get their total welfare. Invertebrates are less likely to be sentient, and have a welfare per animal-year closer to 0 than vertebrates, but there are many more of them. Rounding to 0 a probability of sentience, or welfare per animal-year close to 0 introduces an infinite amount of scope insensitivity. Regardless of the number of beings affected, the change in their welfare will be estimated to be exactly 0.
Furthermore, the probability of sentience of soil nematodes, mites, and springtails is not anything close to Pascalianly low. RP got a probability of sentience for nematodes, which have the least neurons among those soil animals, of 6.8 % under their preferred “#1 High-Value Proxies Model”, and it only ranged from 6.8 % to 6.9 % across the 5 models they considered, although I assume these are far from independent given the proximity of the estimates. I suspect the actual probability of sentience of nematodes is higher. In RP’s words, “Assigning proxies labeled “Unknown” zero probability of being present is certainly leading to underestimates of the welfare ranges and probabilities of sentience [all else equal]”. The probability of dying in a car crash is around 2.70*10^-9 per km (= 10^-6/370), and many people still consider it reasonable to fasten seat belts for increased safety on short trips, even if they would prefer it to be optional.
Effects on soil nematodes should not be neglected just because they may be beneficial or harmful
I expect the interventions I mentioned above to benefit soil nematodes for my best guess that they decrease their population, and that soil nematodes have negative lives. Nevertheless, I got a probability for this of 58.7 %, so I am uncertain about whether the effects on soil nematodes are beneficial or harmful. However, they should not be neglected just because of this. Consider an intervention aiming to decrease the consumption of animal-based foods which:
Increases the welfare of farmed animals, the target beneficiaries, by 1 QALY with 100 % probability.
Decreases the welfare of soil nematodes by 1 kQALY with 30 % probability, and by 0.001 QALY with 30 % probability.
Increases the welfare of soil nematodes by 0.001 QALY with 20 % probability, and by 1 kQALY with 20 % probability.
There is lots of uncertainty about whether the effects on soil nematodes are very negative, barely negative, barely positive, or very positive, but I would not neglect them. They decrease welfare by 100 QALY (= 0.3*(1*10^3 + 0.001) − 0.2*(1*10^3 + 0.001)) in expectation, and therefore the intervention decreases welfare by 99.0 QALY (= 100 − 1*1) in expectation, thus being harmful.
You may well disagree with my numbers above. However, mathematically speaking, “number which is certain to be barely positive” + “number which can be very negative, barely negative, barely positive, or very positive” = “number which can be very negative, barely negative, barely positive, or very positive”, which does not have to be barely positive in expectation. I would only disregard the effects on soil animals if I considered them much smaller in expectation than those being considered.
Estimates of the expected effects on soil nematodes, mites, and springtails cannot be taken literally, but should still be considered
Joey said the following about my estimates of the effects on soil nematodes, mites, and springtails.
I also think about evidence as described in that post from Holden Karnofsky. Here is the summary of it I published in April 2022. I agree on not updating all the way from one’s prior estimate of the expected value to the new one, and on updating less on more uncertain evidence. Yet, as implied by inverse-variance weighting used in meta-analyses, one should also update more given a more uncertain prior. I believe any reasonable prior estimate of the effects on soil nematodes, mites, and springtails will be highly uncertain. So I maintain estimates of the expected effects like mine should still be considered.
I suspect many are misinterpreting Holden’s post due to conflating the prior about the effects on humans with the prior about the effects on all potentially sentient beings. Holden rejects impartiality, which means 1 unit of welfare is always worth the same, even in principle, so he can consider a more certain prior which neglects some effects. I would say one should fully endorse impartiality at least in principle, and therefore consider the prior about the effects on all potentially sentient beings. This prior is much more uncertain than the one about the effects on humans, thus enabling much larger updates towards new estimates of the expected effects on soil nematodes, mites, and springtails.
Effects on soil nematodes, mites, and springtails should be considered even if they are very neglected in society
Many argue effects on soil nematodes, mites, and springtails should only be considered once society cares much more about animals than now. I suspect this results from implicitly supposing that helping animals more inside society’s moral circle, like farmed vertebrates, is more cost-effective. In contrast, I recommend supporting the interventions which at the margin increase welfare the most per $, even if to increase the welfare of animals which are highly neglected in society.
Moreover, some of the most cost-effective ways of increasing human welfare, like GiveWell’s top charities, target people in low income countries, and I estimate they are also among the most cost-effective interventions accounting for effects on soil nematodes, mites, and springtails. My best guess is that these have negative lives, and decreasing human mortality without decreasing food consumption increases cropland, thus decreasing the population of those animals. Humans in low income countries are more inside society’s moral circle than animals, but are still widely neglected. So I wonder what would be the case for prioritising less neglected animals over humans in low income countries. Likewise, I would like to know why the same arguments do not imply prioritising farmed vertebrates over farmed invertebrates, or pets over farmed vertebrates. I suspect many bring up cost-effective moral circle expansion as a justification for why helping their target animals is very cost-effective even accounting for all animals although this did not factor into their initial reasons.
Acknowledgements
Thanks to Vicky Cox for feedback on the draft, and to Zuzana Sperlova for confirming the cost-effectiveness analyses ACE will do this year will rely on RP’s mainline welfare ranges. I listed the names alphabetically. The views expressed in the post are mine.