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In: Journal of Moral Philosophy
Author: Gary David O’Brien
Online Publication Date: 19 Jan 2024
License: Creative Commons Attribution 4.0 International

Note: I'm sharing this paper because I think it's well articulated and explores the implications of a view that I hold (longtermism is probably true and non-human animals matter morally), even though I am not sure if I agree with its conclusions.


Longtermism is the view that positively influencing the long-term future is one of the key moral priorities of our time. Longtermists generally focus on humans, and neglect animals. This is a mistake. In this paper I will show that the basic argument for longtermism applies to animals at least as well as it does to humans, and that the reasons longtermists have given for ignoring animals do not withstand scrutiny. Because of their numbers, their capacity for suffering, and our ability to influence their futures, animals ought to be a central concern of longtermists. Furthermore, I will suggest that longtermism is a fruitful framework for thinking about the wellbeing of animals, as it helps us to identify actions we can take now that have a reasonable chance of improving the wellbeing of animals over the very long term.

Keywords: longtermism; animal ethics; wild animal suffering


Longtermism is the view that positively influencing the long-term future is one of the key moral priorities of our time.1 Since the future has the potential to be truly vast, both in duration and the number of individuals who will ever live, it is plausible that the long-term future might be extremely valuable, or extremely disvaluable. If we care about impartially doing good, then we should be especially concerned to ensure that the long-term future goes well, assuming that it is within our power to do so. Most longtermists focus on humans, and largely ignore animals. This is a mistake. In this paper I will show that the basic argument for longtermism applies to animals at least as well as it does to humans, and that the reasons longtermists have given for ignoring animals do not stand up to scrutiny. I will argue that, because of their numbers, their capacity for suffering, and our ability to influence their futures, animals ought to be a central concern of longtermists. Furthermore, I will suggest that longtermism is a fruitful framework for thinking about the wellbeing of animals, as it helps us to identify effective actions that we can take in the near future that have a reasonable chance of improving the wellbeing of animals over the very long term.

In Section 1 I will lay out the basic argument for longtermism and consider some of the reasons why longtermists have neglected animals. In Sections 2 and 3 I will show that the basic argument for longtermism applies to animals and that we can use the longtermist framework to identify interventions that have a reasonable chance of making the long-term future go better for animals. More specifically, I will argue that (1) now or in the near-term future humans can act in ways that will predictably increase or decrease the scale and duration of wild animal suffering in the long term and (2) we are in an especially influential time for locking in values that can be expected to be good or bad for domesticated animals in the long term. Finally in Section 4 I will suggest some longtermist interventions for animals that might be more effective than short-term alternatives and will suggest areas for further research.

For simplicity, I will assume a hedonistic theory of animal wellbeing, though nothing I say will be incompatible with the view that there are also important non-hedonic elements related to animal wellbeing. I will assume that all vertebrates have the capacity for sentience, and hence for positive and negative welfare. Although I will not have space to argue for this, I will assume the increasingly accepted view that the majority of animals in the wild live bad lives, that is, their lives contain more suffering than positive wellbeing.2 On the view I will assume, the typical wild animal’s life is short, contains little or no positive wellbeing, and ends in a painful death. This is because of the structural features of ecosystems, such as antagonism, scarcity, and reproductive strategies, which are consequences of evolution by natural selection. Since wild animals outnumber domesticated animals many times over, and since wild animal suffering seems to be much more persistent than the suffering of domesticated animals, I will focus more on wild animals than on domesticated ones. However, I will also consider the effects of human practices on the wellbeing of domesticated animals over the long term.

1 The Longtermist Framework

Arguments for longtermism have generally focused on the potential value of the long-term future, though some have also given arguments grounded in our duties to previous generations.3 Though the future-focused arguments differ in their precise forms, all accept some version of these three central premises: the axiological premise that the intrinsic value of good and bad things is unaffected by their location in time, the first empirical premise that the future has the potential to be astronomically large, and the second empirical premise that there are actions we can take in the present and near future that have a significant chance of making the long-term future go better or worse. Putting these premises together with a principle of beneficence we can construct:

1.1 The Basic Argument for Longtermism

(P1)Temporal Neutrality: the intrinsic value of good and bad things is unaffected by their temporal location. An hour of intense suffering is equally intrinsically bad whether it happens tomorrow or in a billion years, and the same is true of the value of good things. We cannot discount the intrinsic value of good and bad things solely because they are in the future.4

(P2)Big Future: the long-term future has the potential to be astronomically large, both in duration and the number of individuals who may ever live. Since individual lives can be very valuable or disvaluable, the long-term future has the potential to be very valuable or disvaluable.5

(P3)Beneficence Principle: in general, when we can do so without too high a cost to ourselves, we ought to help others and promote positive value in effective ways.

(P4)Causal Efficacy: there are actions we can take in the present and near future that have a significant chance of making the long-term future go better or worse.6

(C)The Longtermist Thesis: we ought to take actions which we can reasonably expect will make the long-term future go well when those actions are more effective than the short-term alternatives.

One might accept the first three premises but reject Causal Efficacy. One could either claim that there are no actions that can be expected to have a positive or negative effect on the long-term future, or that we simply cannot identify such actions. Tarsney (2020, 6–7) has called the latter the epistemic challenge to longtermism. It may be that given the difficulties in predicting the long-term outcomes of our actions the best we can do is try to make the near-term future go well. Longtermism might then be an interesting claim about what we ought to value, but it would tell us nothing important about what we ought to do.

Longtermists have developed several conceptual tools which in principle allow them to identify actions that can be expected to have a positive effect on the long-term future, thus securing Causal Efficacy. The first is the concept of a persistent state. A persistent state is a state of the universe which, if made actual, can be expected to last for a very long time, perhaps indefinitely.7 A clear example of a persistent state is a state in which humanity has become extinct. Once humans go extinct that state of the universe will persist indefinitely.8 Another example is the state in which humanity has come under the domination of a global totalitarian regime the primary goal of which is self-perpetuation.9 Greaves and MacAskill use the concept of a persistent state to identify possible actions we can take in the present which will have positive effects on the long-term future despite the general difficulty in predicting such distant outcomes of our actions. They argue that (i) if there are a number of persistent states which could be actualized in the future, (ii) they differ in value, and (iii) there is something we can do now which makes it more likely that the more valuable state will be actualized, then we have identified an action which can be expected to have a significant positive effect on the long-term future. And it appears that all three conditions are met in reality – there are persistent states which differ in value, and humanity can influence the chances of our ending up in these states. Human extinction for example would be persistent, much less valuable than most of the states in which humanity survives, and human beings today have some influence on the probability of our entering that state.

Related to the concept of a persistent state is the concept of value lock-in. A value lock-in is a situation in which the values of humanity (or some significant subset of our values) become so entrenched that they become difficult or impossible to change.10 This is important because our values are a key determinant of what the future will look like, and if we lock in a set of suboptimal values then the future may end up being much worse than it could have been. Ord (2020, 153–155) gives several examples of value lock-ins which could plausibly make the long-term future go worse. These include humanity as a whole renouncing all further technological development, permanently failing to recognize some form of harm or injustice and hence perpetuating it blindly, or permanently locking in a single fundamentalist religion. Another way in which value lock-in might give rise to a sub-optimal future would be if a super-intelligent ai took control of the world and enacted whatever values that its designers had programmed into it.11

Prominent longtermists have generally concentrated on humans and have had comparatively little to say about nonhuman animals. MacAskill (2022, 208–213) briefly discusses the welfare of present-day animals but says little about their future. Greaves and MacAskill (2021) do not mention animals as a possible locus of longtermist concern at all. Bostrom (2013, footnote 23) briefly mentions the possibility that human beings might have a responsibility to help suffering animals in natural environments, and Ord (2020, 212–213) argues that, if humanity survives long enough, we can prevent the natural extinction of animal species over evolutionary timescales, and even transport terrestrial animal species to other planets to prevent their inevitable extinction when Earth becomes uninhabitable. Beckstead (2013, 10–11) explicitly argues on longtermist grounds that it is relatively unimportant to reduce the suffering of animals on factory farms.

This neglect of animals could have serious consequences for their wellbeing over the long term. Beckstead’s argument is particularly concerning. He argues that reducing the suffering of animals on factory farms is relatively unimportant compared to helping human beings, because animals, unlike humans, cannot be expected to engage in activities that will improve the long-term future (2013, 22–23). The assumption here is that by benefiting currently existing people we both benefit them directly and make it more likely that they will engage in socially useful activities, thus generating indirect benefits for more people in the future. These indirect benefits may compound over time, thus outweighing the initial benefit to the original people. Benefiting animals does not provide such indirect benefits. Helping humans then is like investing in capital, with the expectation that the investment will pay off in the long run. Helping animals is like a moral cul de sac – whatever resources we invest into making animal lives go better will not be returned as animals are incapable of contributing meaningfully to the value of the long-term future. This argument ignores the fact that helping animals is not necessarily only of value in the short term. Effective ways of helping animals might have long-term positive effects too. Beckstead gives the example of giving pain relief to animals on factory farms. He may be right that this is of only short-term efficacy, helping only those animals we give the pain relief to, without any positive indirect effects. Abolishing factory farming altogether or replacing animal agriculture with synthetic meats is an entirely different matter. Stopping factory farming would not only help animals in the short term, but it would also prevent the suffering of many animals into the long-term future.

Beckstead (and perhaps other longtermists) may be assuming that animal agriculture is likely to be supplanted by synthetic animal products or plant-based agriculture in the near term, and so efforts by activists to abolish it can, at best, slightly speed up this inevitable transition. If this were true, then activism might not be an effective longtermist intervention. However, the abolition of animal agriculture is not inevitable. Though we may have the technology to do so soon, such a change depends not only on our technology, but on our values, and as MacAskill points out in his discussion of the abolition of slavery (2022, 62–70), we cannot assume that such moral progress is inevitable. It is possible that humanity might soon perfect the technology to create ‘animal’ products synthetically, yet due to suboptimal values they might continue to engage in animal agriculture indefinitely. For example, if humanity maintains speciesist values, and if consumers prefer ‘natural’ or ‘authentic’ animal products to synthetic ones, then we may continue factory farming animals indefinitely despite having the technology to do otherwise. It is also possible that we will invent new ways to exploit animals. For example, developments in the technology of xenotransplantation may make the breeding of genetically modified animals for organ transplants commonplace. It is also already possible to create genetically modified immunodeficient animals for use in medical research. These are animals in which the immune system has been deliberately impaired so that they are more susceptible to various diseases, infections, or tumor growth, and hence more useful for the scientists researching these diseases.12 As our gene-editing technologies become more powerful it may be possible to create many more kinds of suffering animals for use in research. Finally, it is also possible that our moral values regarding animals get worse rather than better. If that happens, then we might exploit animals in ways that are unthinkable today. We cannot simply assume that moral progress in our treatment of animals is inevitable; rather we must ensure that humanity makes this transition by promoting values that are more friendly to animals. Furthermore, as I will argue in Section 3, we may be in a particularly important time in which to try to shift human values regarding animals. If this is correct, then morally informed activism for animals may be an extremely important longtermist concern.

Ord recognizes that we may have some duties towards animals, but seems to think of these as duties to animal species rather than to individual animals, and consequently his suggestions for how to help them are potentially harmful. Ord thinks that it would be a good thing for humanity to relocate animal species to other planets to ensure their survival once Earth becomes uninhabitable. If wild animals generally lived good lives, then spreading them beyond Earth might be a good thing. However, in recent years the problem of wild animal suffering has been increasingly recognized in the animal ethics literature. It is possible that most wild animals live bad lives, and if this is the case, then spreading wildlife to other planets might cause a huge amount of suffering for a very long time. I will discuss the problem of wild animal suffering (WAS) from a longtermist perspective in Section 3.

In Sections 2 and 3 I will argue that the basic argument for longtermism applies to animals. In Section 2 I will argue that we ought to be concerned about how the long-term future goes for animals by showing that Temporal Neutrality and Big Future apply to them. In addition, I will suggest two further considerations which make it particularly important to think about the long term for animals, based on our future capacities to help wild animals and the higher stakes for animals than for humans. In Section 3 I will argue for Causal Efficacy. Using the longtermist concepts of persistent states and value lock-in, I will argue that there are actions that we can take in the near term which have a reasonable chance of making the long-term future go better for animals. If these arguments are successful, then the longtermist thesis applies to animals.13

2 Temporal Neutrality and Big Future

It is difficult to see how Temporal Neutrality could apply to the wellbeing of humans but fail to apply to that of animals. For this to be the case there would have to be some relevant difference between human and animal wellbeing that makes it rational to think that future human wellbeing is as valuable as present-day human wellbeing but the same does not hold for animal wellbeing. It is difficult to imagine a candidate difference. As we saw above, Beckstead argues that, from a longtermist perspective, it might be less important to confer benefits on currently existing animals than on currently existing people, as the latter, but not the former, can contribute to improving the long-term future. This is a difference between benefiting humans and animals, but it is not the right sort of difference to make Temporal Neutrality apply in one case and not the other. This is because Beckstead’s argument concerns the comparative instrumental benefits of conferring intrinsic benefits on people and on animals, but what we would need is an argument that allows us to discount the value of future intrinsic benefits for animals but not for humans. Since such a difference is not forthcoming, I will assume that Temporal Neutrality applies equally to animals, and that we ought to be as concerned about future animal wellbeing as present-day animal wellbeing. In fact, it might be the case that Temporal Neutrality applies even more strongly to animals than it does to people. One might think, for example, that some of the strength of our moral obligations towards other people alive today comes from the fact that we are enmeshed in special relations of various kinds. Some people alive today are our family and friends, some are fellow citizens, some are engaged in the same projects as we are. Some of these special relations can be expected to disappear over time, thus reducing the strength of our obligations towards future people to whom we are not so specially related. It is plausible however that our duties to animals are not based on any kind of special relationships, and so their strength does not diminish over time. If this is right, then while our obligations to future people might diminish somewhat as the relations between us weaken, the same is not true of animals.14

It also seems likely that the Big Future premise applies at least as well to animals as it does to humans. At present there are around 8 billion human beings on the planet, but we are outnumbered by other sentient vertebrate animals of whom there are at the very least 10 trillion (10^13) and perhaps more than a quadrillion (10^15) (Tomasik, 2019). On conservative estimates, then, animals outnumber human beings by between a thousand and a hundred thousand to one, but the true population of animals may be orders of magnitude higher. Bristlemouth fish alone may number in the quadrillions (Woods Hole Oceanographic Institution, 2019). This means that most sentient individuals are nonhuman animals. If we assume that animal and human populations will remain at the same ratio in the long term, then the long-term future has the potential to contain far more animal suffering and wellbeing than human suffering and wellbeing. If we are impartially concerned with maximizing wellbeing and minimizing suffering, then we ought to be very concerned about the long-term future of nonhuman animals on the assumption that they will continue to constitute the vast majority of welfare subjects. If Big Future inclines us to take longtermism for humans seriously, then it should also incline us to take longtermism for animals seriously.

It might be objected here that it is unlikely that animal populations will remain at their current levels. Animal populations might decline drastically and remain at low levels for the rest of our planet’s period of habitability. In fact, it seems that wild animal populations have decreased dramatically in the past 50 years, as human development has reduced the habitats for many species, and this process might continue until relatively few wild animals remain. A 2020 report by the wwf suggests that there has been a 68% decline in the average populations of monitored vertebrate species since 1970. It must be borne in mind, however, that this report is concerned specifically with biodiversity, not with animal populations generally, and the findings of the report are compatible with global animal populations staying the same or increasing. For example, the report mentions invasive species as a major cause of biodiversity loss (2020, 22, 54) but if invasive species are replacing native ones this need not cause a net decrease in animal populations. Similarly, reductions in the numbers of large animals can be more than compensated for by increases in the numbers of small animals. Other causes of biodiversity loss more clearly seem to indicate general population declines, however. Future humans might also eliminate domesticated animal populations, for example by switching from animal agriculture to plant-based or synthetic alternatives. If this happens then the Big Future premise is not true of animals, and so the longtermist thesis does not apply to them.

In response, we cannot simply assume that animal numbers will drop significantly and remain low indefinitely. This will depend in large part on the values and actions of human beings over the coming centuries, and these are yet to be determined. Even if one were somehow certain that humanity will eventually drive all the other animals to near extinction, in order to do so humanity itself must survive long enough. Ord (2020) puts the risk of human extinction within the next century at about 17%. Newberry (2021, 4) cites several experts on existential risk who also put the risk at around 20% in the next 100 years. If one accepts that there is a significant risk of human extinction in the next 100 years, then in order to maintain that there is a high probability that humans will drive animal populations to near extinction one would also have to believe that they will do so relatively soon, and that animal populations will never rebound after human extinction. Secondly, as we will see in Section 3, there are some ways in which humanity could ensure a long future for animals even if animals do eventually go extinct on Earth. Thirdly, if one believes that animals generally live good lives, or that they could live good lives with human assistance, then one ought to be concerned about animal extinction too, as this might reduce total wellbeing in the long term.15

A more fundamental point is that longtermists generally think about the size of the future in terms of expected population, rather than in terms of the most likely outcome or the median across various possible outcomes.16 In essence this means that they generate high and low estimates for possible future populations then weigh them according to their probabilities thereby establishing a figure for the expected population. They find that, since human populations have the potential to be truly vast, the resulting figure is also vast, even when they account for the possibility of very low populations or total extinction. As Greaves and MacAskill say:

Even a 50% credence that the number of future beings will be zero would decrease the expected number by only a factor of two. In contrast, a credence as small as 1% that the future will contain, for example, 1 trillion beings per century for 100 million years … increases the expected number by a factor of 100.

The same consideration applies to the animal population – since it has the potential to be very large, we would need to have an unreasonably high degree of confidence that their population would decline to zero or near-zero in order to endorse a low figure for their expected population. But, if a high expected human population is sufficient to ground longtermist concern for human beings, then a high expected population of animals ought to be sufficient to ground longtermist concern for them too.

There is one final consideration relevant to the application of the Big Future premise to animals. Longtermists often bolster their case by arguing that human beings might one day colonize other planets, or that we might one day create human minds on computers, all of which would multiply the possible future population enormously.17 If we consider such huge expansions to the human population likely, but think it very unlikely that future animal populations will be expanded in the same way, then we might be justified in thinking that the vast majority of future sentient beings will be humans (or digital human minds) and so it is much more important to ensure that the long-term future goes well for them than for animals.18 That is, though the absolute number of animals in the future remains large, it would be dwarfed by the human population, and thus rendered irrelevant to our longtermist decision-making.

This is of course highly speculative. There is no reason in principle however why these technologies could not also multiply animal populations. Tomasik (2018) speculates about the possibility that future human beings might choose to create digital worlds replete with sentient digital animals, perhaps in natural settings similar to those on Earth in which they might suffer greatly. Future humans might also choose to create digital minds in order to maximize hedonic wellbeing, and since animal minds are so much simpler than human minds they might do so by creating digital animal minds rather than digital human minds. A human brain contains around 86 billion neurons, while a mouse brain contains a mere 70 million. Assuming that the difficulty of creating a digital mind increases proportionally with the number of neurons required, then a utility-maximizing would-be digital mind creator might be advised to create digital mice rather than digital people. In Section 3 I will consider the possibility that humans might one day spread wild and/or domesticated animals to other worlds. Here I will only say that this possibility is not negligible, and in fact there are some ways in which it is much easier to spread animal life than human life, and so we cannot discount the possibility that animal populations will also be multiplied across physical and digital space. It is possible therefore that animal populations will be multiplied by these technologies just as human populations might be. Even if we think this unlikely, so long as we do not think it impossible, the huge numbers involved serve to increase the expected future animal population significantly.

Of course, it is extremely difficult to make accurate predictions about far future population sizes for humans or animals. There are so many known and unknown factors that could cause the population to increase dramatically, fall to zero, or anything in between. This uncertainty may count against the plausibility of longtermism generally but is not an argument against including animals in the longtermist framework. To show that Big Future is true of humans but not of animals it is not enough to point to the uncertainty about future population sizes. Rather, it must be shown that there is an asymmetry between humans and animals which means that, while the future human population is large in expectation, the expected future animal population is not. I have argued above that there is no such asymmetry – if we believe that the expected human population is large, we should think the same about the expected animal population. Furthermore, there are some factors which give us reason to expect a large animal population rather than a large human one. For example, humans are just one species among many. We are an exceptional species, and it is likely that we have the means to survive threats to our existence which other animals do not, and so perhaps we are less likely to go extinct than other species. However, there are millions of species on the planet. Though our likelihood of going extinct might be lower than that of any other species, it is unlikely that our chances of survival are greater than those of all other species on Earth combined. It may be the case then that humans go extinct while other animals live on indefinitely, thus ensuring Big Future for animals, but not for us. If it is unwarranted to be confident about the size of the future human population, it is doubly so to be confident that our population will increase and the population of animals will shrink or vanish.

Finally, there are two considerations that indicate that longtermism is particularly important for animals. The first concerns our current capacity to help wild animals, which is far more limited than it is likely to be in the future if we act today to ensure that we expand that capacity. It is presently possible to help wild animals in limited ways by vaccinating them against some diseases, leaving out food supplements in times of extreme scarcity, and rescuing and rehabilitating them when they are affected by natural catastrophes. The main causes of wild animal suffering, however, are systemic features of the natural world, primarily reproductive strategies, endemic scarcity, and various forms of antagonism, including predation, which we currently have little ability to influence. In order to seriously improve the lives of wild animals we need to develop our scientific knowledge of the causes of suffering and wellbeing in diverse species of wild animals, we need to understand how the various components of the biosphere interact so that we can better predict the results of our interventions, and we need to develop the technology to intervene safely and effectively. These developments may take decades or centuries to come to fruition. Those who are concerned with animal wellbeing might therefore think that it is important to begin the research work that will allow us to significantly help wild animals in the future.

The second consideration concerns the relative stakes for humans and animals in the future. The bad futures for humans considered by longtermists often involve premature extinction, or failure to reach full technological maturity. Futures like these are only ‘bad’ compared to the positive futures which we could have, but they are not intrinsically bad. Of course, there are possible futures in which human beings suffer significantly, for example if a sufficiently bad global totalitarian regime took over, or if a super-intelligent ai came to positively value human suffering, but these futures are relatively unlikely. The most likely futures open to animals on the other hand are intrinsically bad, in the sense that they involve large amounts of suffering for large numbers of animals over very long periods. Unlike humans, who have the intelligence and technological skill to solve the problems facing them, animals seem almost helpless against the natural forces that cause them to suffer. We might say that the default state of animals is to suffer. Since the most probable long-term futures are extremely bad for animals, we have additional reason to take measures today to try to change our trajectory to avoid those futures.

3 Causal Efficacy

In this section I will argue that Causal Efficacy applies to animals. By utilizing the longtermist concepts of persistent states and value lock-in, it is possible to identify some actions that we can take today that we can reasonably expect to make the long-term future go better or worse for animals. First, I describe WAS as a negative-value persistent state which, absent human intervention, we can expect to last for a very long time. I also describe some ways in which human agency could increase the scale and persistence of WAS. Second, I argue that there is a danger that humanity might lock in values which will make the long-term future much worse for animals by spreading and perpetuating animal exploitation, and by making future people less concerned about mitigating WAS. Furthermore, if it is the case that humanity will soon expand into space, then this is a very strategically important time at which to avoid locking in bad values.

3.1 WAS as a Negative-Value Persistent State

On Earth trillions of animals suffer and die painfully each year as a result of purely natural processes, while a much smaller number seem to live good lives. It is likely that the vast majority of lives lived by wild animals today are bad, and plausible that aggregate welfare across all lives on Earth is also negative.19 Furthermore, this does not seem to be an accidental feature of life on our planet; rather it is caused by structural features of evolution by natural selection, and so WAS is likely to continue to dominate animal wellbeing for as long as life on Earth continues to be governed by those processes. In fact, since these natural harms are the predictable result of natural selection, it is reasonable to think that similar outcomes will obtain on any planet on which sentient life evolves.20 It is difficult to quantify just how bad WAS on Earth is, but we can make some reasonable estimates. Extremely conservatively we can say that ten trillion animals die each year after enduring only 1 minute of net suffering. This would amount to approximately 18.2 million years of experienced suffering each year across all animals on Earth. If this does not sound that bad, remember that the degree of suffering that we are talking about is high – for example, being eaten alive or dying of starvation. This estimate is highly conservative in many ways. First, it takes the lowest estimate of wild animal populations. Second, it falsely assumes that the number of deaths per year is equal to the number of animals alive at any given time, but since the vast majority of animals are small short-lived ones who breed frequently and in vast numbers, the number of deaths per year must be much higher than this. Third, it assumes only one minute of net suffering. This may be true of animals such as small fish who are quickly eaten by predators immediately after hatching, but it must be remembered that many animals also starve, or die from disease, and even those who are killed by predators must sometimes endure more than a minute of suffering from being pursued and eaten more slowly. A reasonable higher estimate would be that there are a quadrillion deaths per year. If we assume again only one minute of net suffering each, that comes to 1.82 billion years of experienced suffering per year.

If we accept these arguments, it is clear that WAS is a negative-value state. It is also a highly persistent one. Sentient animal life has existed on our planet for around half a billion years, surviving numerous mass extinction events, and life itself has survived for around four billion years. While individual animal species come and go, sentient animal life is much more robust. Given that sentient animal life has already endured so long, it is highly likely that it will endure as long as Earth is habitable, another billion years or so. And since WAS is not an accidental feature of life on our planet, but emerges predictably from necessary structural features of natural selection, it is highly likely that as long as sentient life endures, suffering will dominate wellbeing, unless humans intervene.

There are actions human beings can take in the short term that alter both the scale of WAS and its persistence. If, for example, humanity goes extinct, this could both increase the scale of WAS by freeing up more land for animals thus increasing their population, and its persistence by removing the only technologically capable animal on Earth that might one day be capable of significantly reducing WAS.21 Somewhat surprisingly then, humanity’s continued existence might be a good thing for wild animals.22 It is also possible that humanity will increase the scale of WAS by spreading animal life beyond Earth.23 This could be done directly, by bringing wild animals with us to establish a biosphere when we colonize other planets. We could also do this indirectly, by launching ‘directed panspermia’ missions aiming to spread microbial life throughout the galaxy in the hope that some of the microbes will survive and evolve on the target planets, eventually giving rise to complex biospheres with sentient animals. Such missions are possible using current-day or near-future technology, and they would be a relatively cheap way of spreading life throughout the galaxy.24 It is also possible that we will spread life accidentally, for example by failing to decontaminate spacecraft originating from Earth, thus introducing terrestrial microbes to other planetary bodies where they might eventually evolve into more complex sentient life. It is very difficult to completely decontaminate spacecraft, and essentially impossible to eliminate the millions of microbes that live on, and in, human astronauts. Some scientists have already suggested that contamination of other planets is inevitable, and this should be seen not as regrettable but as a good thing, with microbes forming a first wave of colonization of other worlds.25

Such actions would not only increase the scale of WAS by multiplying it across other planets, but they would also make it more persistent. Though life has survived on Earth for four billion years it is still possible that some global cataclysm might eliminate life on the planet. By spreading life to other worlds we would be increasing the chances that sentient life, and hence WAS, will persist for a very long time. Furthermore, even if no extinction event occurs, our planet has a finite period of habitability. Other planets may have longer periods of habitability than our own. It is also possible that we could spread life to planets which orbit stars like our own, but at an earlier stage in their development. WAS on Earth is bad, but human action could result in WAS that is vastly greater in scale and much more persistent.

The fact that humanity can make the long-term future worse for animals is sufficient to secure Causal Efficacy. It is also possible, however, for us to take actions that we can reasonably expect to make the long-term future go better for animals. We know the causes of WAS, and in principle it is possible for us to systematically intervene in the natural world to mitigate the suffering endured by animals, or even to enhance animals so that they are more likely to live happy lives. We already intervene in nature on an ad hoc basis to help wild animals, albeit for anthropocentric reasons. The ultimate causes of WAS, though, are genetic – most animals have evolved to have huge numbers of offspring, the vast majority of whom will die soon after birth, and many other animals have evolved to prey upon or parasitize other animals. To eliminate WAS, then, would likely require genetic editing of wild animals. It would also require extensive understanding of the functioning of ecosystems so that our interventions do not have unintended bad consequences. The precise nature of the interventions required must be determined by scientists, and the technology and understanding required for successful interventions are likely to be decades away. We cannot know at this point whether this will be successful. It might be the case that the best we can hope to do is to mitigate WAS somewhat. On the other hand, it might be the case that future science and technology will enable us not only to greatly reduce WAS, but to ensure that most animals have good lives. When we remember just how bad WAS is, and just how long it could last, however, it should be clear that even a slim chance of success has tremendous expected value.

3.2 Value Lock-In

Animals, whether wild or domesticated, are almost entirely at the mercy of human beings – whatever values we have will in large part determine their futures. The values held by most human beings today are disastrous for animals. Most humans are speciesists – they think it is acceptable to sacrifice the most important interests of animals in order to satisfy the most trivial interests of humans. This is most obvious when we consider the animals we exploit for food. If humanity maintains these anti-animal values, this will likely have very bad consequences for animals, as we will continue to dominate and exploit them indefinitely. Anything we can do to undermine speciesism, and to shift humanity to more animal-friendly values can be expected to improve the long-term future for animals.

Furthermore, we may be in an especially critical period regarding the impact on the future that our attitudes to animals could have. It is not unreasonable to think that humanity might begin colonizing space within the next century.26 If we maintain those speciesist values which underlie our mass exploitation of animals, it is possible that we may take domesticated animals with us and multiply our exploitation of animals across other worlds. Scientists have already made proposals for establishing systems of animal agriculture off Earth, and as our spacefaring technology develops, more such proposals may be made.27 If there is no shift in our values regarding other animals, it seems likely that we will continue to exploit them in space if it is technologically and economically feasible to do so. On the other hand, if we change our values regarding animals before we begin colonizing other worlds, then it is unlikely that we would take animals with us to exploit, given the technical challenges and costs involved. The possibility of human expansion into space brings a greater sense of urgency to abolishing our practices of animal exploitation. If we expand into space and colonize other planets before eliminating industrial animal exploitation, then colonists are likely to bring some domesticated animals with them. Once colonies are established on other worlds, cultural differentiation may be inevitable, so that even if we subsequently renounce speciesism on Earth, colonists on other worlds may retain speciesist attitudes.28 If that happens, then further colonization originating from these worlds may spread animal exploitation throughout the galaxy, even if the population of Earth abandons animal exploitation.

There is an opportunity then to lock in anti-speciesist values here and now, thus significantly reducing the probability of spreading animal exploitation to other planets. If we abolish animal exploitation before we begin colonizing space, this will reduce the possibility of spreading animal exploitation beyond Earth in two ways. First, all colonists leaving Earth would start out with anti-speciesist values, and all our colonies would have to revert to speciesist values independently. Secondly, colonies would have no stocks of domesticated animals as we would not bring any with us from Earth, and so obtaining animals to exploit on colony worlds would be much more difficult. It is possible that humans will begin colonizing other worlds later this century. Given this possibility, and the strategic advantage of locking in anti-speciesist values before expansion begins, this may be the most important time to promote anti-speciesist values. After colonization it may be too late to prevent the spread of animal exploitation throughout the galaxy. The expected value of efforts to shift human values away from speciesism may be much higher now than they will be after space colonization has begun. We are at a crucial point in the history of humanity, and the values that we settle on may determine the fates of countless animals.

4 Longtermist Interventions for Animals

In this section I will suggest some interventions that present-day or near-future humans can take in order to increase the likelihood of the long-term future going well for animals. These suggestions are tentative, however – much more empirical research is required to determine how effective they would be. Nevertheless, they are sufficient to demonstrate that longtermism may be a fruitful framework for thinking about animal wellbeing. Some of these interventions have the potential to be highly effective, perhaps more so than the best short-term interventions, and people concerned with reducing the harms suffered by animals should consider them. Furthermore, some of these interventions are scarcely even conceivable on a more short-term focused framework. Though these suggestions for improving the long-term future for animals are highly speculative, the same is true of most longtermist suggestions for improving the human future.

4.1 Reducing the Likelihood of Spreading WAS

One of the easiest ways in which humanity could make the future worse for animals is by spreading wild animal life to other planets, where natural selection will almost inevitably result in mass suffering. As we saw in section three, this could be done deliberately by direct colonization or by launching directed panspermia missions, or accidentally, by contaminating other planets with microbial life. To see how bad this could be, let us imagine that we spread life to just one other planet, and that sentient life will survive there for a billion years. Taking my most conservative estimate for the amount of WAS on Earth each year and multiplying that by a billion years we get 18.2 quadrillion years of animal suffering for one planet. If there is some action we can take that reduces the chances of spreading wild animal life to one other planet by just 0.1% that action has an expected value equivalent to preventing 18.2 trillion years of suffering. I have calculated elsewhere that the annual suffering of animals we exploit for food comes to about 16 billion years every year.29 Reducing the probability of spreading WAS to one other planet by 0.1% has an expected value equivalent to stopping all suffering caused by exploiting animals for food on Earth for over a thousand years. One could of course question my calculations here. However, it should be borne in mind that I have been extremely conservative in my estimates of the amount of WAS experienced annually on Earth, and in my presumption that whatever action that we take to prevent the spread of WAS would only prevent its spread to one planet.

Taking the figures I have given at face value, it is at least plausible that such interventions might be more effective than most short-term ones. Of course, we will not know how effective they might be until we know exactly what form they will take, how much they will cost, and how the cost/benefit ratio compares to short-term interventions on behalf of animals, all of which must be the subject of empirical work. Tentatively I suggest the following:

(1) strict legal controls over space technology, enforced by a suitable international body which prohibits spreading nonhuman life to other worlds, whether directly or via indirect methods such as directed panspermia, and which enforces

(2) strict decontamination procedures for spacecraft originating from Earth, whether they are scientific, exploratory, or industrial, thus lowering the risk of accidental contamination


4.2 Reducing WAS on Earth

It may be possible for humanity to develop the science and technology required to safely intervene in nature to remove the causes of WAS and thereby reduce the suffering of wild animals, perhaps to the point at which most animals live net positive lives. If such interventions were successful and long lasting, they could make the long-term future far better for animals. It is difficult to say exactly how good such a future might be, but I will attempt a very rough estimate. Again, taking my conservative estimate of the amount of net WAS on Earth (18.2 million years per year) we can imagine that a successful intervention program would eliminate this suffering, and replace it with the same amount of mild positive wellbeing, giving us a net of 18.2 million years of mild wellbeing distributed across all wild animals on Earth each year. If we imagine this state enduring for the remainder of Earth’s period of habitability, this comes to 18.2 quadrillion years of wild animal wellbeing. Even a tiny chance of success would have a very high expected value in terms of reducing suffering and promoting positive wellbeing for vast numbers of animals.

Reducing WAS on Earth is likely to be much more difficult and costly than preventing the spread of WAS to other planets, and at this point it is not possible to say how cost-effective such interventions would be compared to other long- or short-term interventions on behalf of animals. There are some considerations which do favor an interventionist program, however. First, though likely to be expensive, most of the costs will be at the research and development stage – the interventions themselves are likely to be automated processes rather than a continual hands-on process of ‘policing’ nature. For example, gene drives can be used to spread desirable traits through the animal population, and once developed and released into the target population, the rest of the process is automatic.30 If we consider the costs of research and development to be fixed costs which will continue to benefit wild animals indefinitely, then such research may in fact prove highly cost-effective. Secondly, at least some interventions in nature are highly persistent in the face of natural changes, so they would remain effective for a very long time even if human beings were no longer around to maintain them.31 Finally, if humanity ever does manage to intervene in nature so effectively that most animals in fact have good lives, there is no reason in principle why we could not then utilize this knowledge and technology to spread happy animal life to other planets, thus multiplying the positive welfare effects across many worlds. I suggest:

(3) investing in the research and development of the technology required to safely help wild animals on a large scale

(4) supporting efforts to reduce existential risk to humanity, since without human beings there is little prospect of WAS being eliminated


4.3 Shifting to More Animal-Friendly Values

It is plausible that speciesism underlies our willingness to exploit nonhuman animals. It is unclear to what extent speciesism can be combated, and what the best methods of doing so are. The rise of veganism gives grounds for optimism though. Furthermore, research has shown that speciesism is related to other prejudices like racism and sexism; if the latter have declined over time then it might be possible to reduce the former too.32 Finally, several studies have shown that speciesist attitudes emerge between the ages of 11 and 18, and that they are socially acquired, and thus it seems that it ought to be possible to educate children differently so that they adopt more animal-friendly values instead.33 Therefore I suggest:

(5) promoting anti-speciesism and/or moral circle expansion34


Finally, it is plausible that speciesism also underlies humanity’s general lack of concern for WAS and resistance to the idea of intervening in nature on a large scale to reduce it, though I am not aware of any research on this question. In any case, I suspect that speciesism is only part of the explanation for our indifference to WAS. It is also likely that most people are simply ignorant of the scale and severity of WAS. I suggest:

(6) education on WAS, and attempting to move the general public away from valuing nature in a purely holistic fashion and towards an appreciation of the value of individual sentient animals

I do not pretend to have shown that these interventions would be effective – much more research is required to determine their feasibility and cost-effectiveness. However, they may be a promising place to begin research into longtermist interventions on behalf of animals. Furthermore, I hope that these suggestions are plausible enough that animal advocates who are not longtermists may at least consider the utility of adopting a longtermist framework when thinking about how to promote animal welfare, both because they have the potential to be effective, and because some of the proposed interventions are scarcely even conceivable within a short-termist framework.


I have argued that the longtermists’ neglect of animals is a serious mistake. It may also be a mistake for animal ethicists to ignore the long-term future. The basic argument for longtermism applies at least as well to animals as it does to humans, and the longtermist framework may be a useful way of identifying highly effective interventions to improve the wellbeing of animals into the long-term future. Much more research is required to determine which interventions would be most effective, and how they compare with short-term or human-focused ones. Finally, there are many important questions relating to the long-term future of animals that I have not addressed here. For example, there may be important non-hedonic values relating to animals that we might want to promote in the long term, such as the esthetic value of biodiversity or of having a wide variety of forms of sentient happy animal life. We may also have some duties to make the long-term future better for animals which are grounded in the past. As Ord suggested, we might want to try to ‘make amends’ for our past mistreatment of animals, though by considering individual animals rather than species, and with an awareness of the scale of WAS. Or, given the hundreds of millions of years of animal suffering which were necessary for the evolution of our species, we might think that we have reason to make the future better for animals, so that, in Parfit’s words, “the existence of the Universe will have been on the whole good.”35 The history of sentient life may be only just beginning, and we ought to use our influence to ensure that it goes as well as possible.


For very valuable feedback on multiple drafts of this paper I would like to thank Guy Kahane, Jeff McMahan, and Oscar Horta. I would also like to thank Rhys Borchert, Adam Gibbons, Josh Milburn, Rhys Southan, and Yip Fai Tse.

Funding for this paper was provided by the organization Animal Ethics. The views expressed in it are my own.

Biographical Note

Gary David O’Brien is a Research Assistant Professor at the Department of Philosophy in Lingnan University.





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While I only had time to quickly read this piece, I agree with much of what I read and think it is a great contribution to the literature. 

To clarify my own view, I think animals matter a great deal — now and over the longterm future. The focus on humanity in my work is primarily because we are the only moral agents we know of. In philosophical terms, this means that humanity has immense instrumental value. If we die, then as far as we know, there is nothing at all striving to shape the future of Earth (or our whole galaxy) towards what is good or just. It is with humanity in this role as moral agent, rather than moral patient, that I think the case for avoiding existential risk to humanity is at its most powerful. I don't know whether the lion's share of intrinsic value we create over the longterm future will be in the form of human flourishing, animal flourishing, or something else, and welcome much more discussion on that, with your paper being a good example.

As well as avoiding existential risk, I think that work to avoid locking in bad values or practices could also be very important on longtermist grounds, and that values connected to animals are good candidates.

I focused on what could happen to animal species rather than individual animals in those particular passages, but much of my thinking on animal ethics is in terms of individuals. 

Like most people, I'm not sold on the idea that wild animal suffering makes the biosphere have negative overall value, such that ecosystem destruction would be good instead of bad (and so forth). But nor am I claiming that we should introduce animals to other planets. My point in those passages was to sketch the magnitude of the kinds of things humanity could achieve in terms of the environment and animal life. What to do with that power raises very big and very uncertain questions. My main claims were that we should protect our potential, and then think very long and hard about how best to fulfil it.

I didn't write the paper, but thank you for the comment, Prof. Ord! I appreciate your perspective.

I also personally am not sold on the biosphere having negative overall value. I think the immense number of sentient beings that spend large portions of their lives suffering makes it a real possibility, but I am not 100% sure that utilitarianism is true when it comes to balancing wild animal welfare and broader ecological health. I think that humanity needs to spend more effort figuring out what is ultimately of value, and because the ecological view has been dominant in environmental ethics to date, I believe the WAW view deserves more consideration and to be integrated into humanity's thought process even if it is not ultimately accepted.

Yes, I completely agree. When I was exploring questions about wild animal welfare almost 20 years ago, I was very surprised to see how the idea of thinking about individual animals' lives was so foreign to the field.

Thank you so much for this article! (BTW: Are Gary David O’Brien and BrownHairedEevee the same person? If not, also thanks to the latter for sharing it.)

I was wondering myself for years why longtermists seemingly didn´t really account for (non-human) animals, since it seems quite obvious that in a lot (if not most) of the possible futures, humanity will be nothing but an insignificant minority of all the sentient beings. In fact, my personal motivation for caring about X-risks is mostly due to the instrumental value humanity might have in regards to non-human wellbeing.

Well, I still am wondering, since besides of Beckstead´s argument (which is not really about intrinsic values) you also didn´t mention any particuar arguments human-focused longtermists actually made in regards to this. So I´m still curious why this topic gets so little attention, aside of speciesist reasons (which I am hoping are less common among longtermists compared to the rest of society). Maybe part of this is because the argument for longtermism gets even harder if you also want to convince your audience to abolish speciesism at the same time?

In any case, I completely agree it is a mistake to neglect animals in longtermism.

Im less convinced that WAS is actually a net-negative state. (My guess, though I wouldn´t really call it an informed one, would be that in average an animal in the wild lives a moderate-positive life, despite all the horrors. This average probably depends mostly on insects and small animals in the ocean, however, and I´m really not an expert, so I cannot exculde the possibility that my guess is only wishful thinking.) While this discussion in general is probably better lead elsewhere, I would at least note that your "reasonable estimate" about 1-minute-suffering before any death seems like a good estimate about some of the suffering, but is not really a reason to believe it is also a good estimate about the net-value, since it focuses on one particularly bad minute in a far longer life and does not really tell us anything about the expected value of given life as a whole. (Which would probably be highly dependent on the species.)

If WAS were actually net-positive, it would change a lot in your conclusion about preventing the spread of animals outside of earth. (And sadly also about the current influence of humanity on the overall wellbeing.)

However, most of the arguments (and especially the conclusion that it is a mistake to ignore animas in longtermism) are valid regardless, since it is true in any case that humanity might heavily influence the duration, spread and quality of wildlife as well as the exploitation of farmed or engineered animals.

Best regards,


Hi, no, I'm not the author of the paper. I edited the top of the linkpost to indicate that.

Thanks for sharing, Eevee!

I'm excited to see where animal inclusive longtermism can go and what interventions begin to develop in this space.

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