Can. They. Suffer.

by Jeroen Bouterse

Human treatment of animals is a moral calamity at an outrageous scale, that I can get from zero to really quite worked up about in a matter of seconds. For fear of hurting the cause, I allow myself to take part in polite conversation about the dead bodies on the dinner table only if there is a more soft-spoken ally nearby. Two minutes into the conversation, when I find myself suppressing the urge to yell at a meat apologist how that kind of excuse might equally well be used to justify eating human babies, I am often grateful that there is somebody who can steer the conversation instead towards the socially acceptable topic of plant-based recipes.

It especially helps if they look fit (which they always do!), and are able to say with a straight face that “it’s perfectly simple to lead a healthy lifestyle and cook a tasty dinner without using meat”. Meanwhile, I don’t know how to cook a tasty dinner no matter the ingredients, and I have rarely given a moment’s thought to what it takes to lead a healthy lifestyle. It’s completely beside the point, is what I’m really thinking while nodding along. We were not talking about precisely how full of life everyone feels when their alarm clock rings, were we; we were talking about the food on your plate; about the moral issue, about the crime

Luckily, things do not depend on my ability to express myself eloquently and effectively without alienating everyone present. I can also simply try to nudge people towards reading Peter Singer, especially now that he published an updated version of his Animal Liberation. What follows are basically my notes from reading this 2023 edition, with very few thoughts of my own mixed in. If you have immediate access to the book itself, switch to that; if not, you might as well keep on reading and buy or borrow it afterwards.

Equality for animals

In the first chapter of Animal Liberation Now, Singer makes the case for a general principle of equality. He interprets the idea of human equality as the principle that everybody’s interests equally merit consideration, regardless of differences in abilities. “Equality is a moral ideal, not an assertion of fact”. Once we see that the condition of actual equality does not apply, there is no reason why equal consideration should not extend beyond humans to everybody and everything that has interests. The capacity to suffer or to be happy, which leads to you having interests at all, ought to be sufficient for your interests to count. “The question is”, Singer quotes Jeremy Bentham approvingly, “not, Can they reason? nor Can they talk? but, Can they suffer?”

Singer presents the extension of the moral idea of equality to animals as to some extent analogous to its extension to marginalized people. He believes that this interpretation of equality is not only more sound in principle, but also more robust in practice than the idea of equal capacities: it is not vulnerable to the anti-egalitarian objection that humans are not in fact all the same. “If the demand for equality were based on the actual equality of all human beings, we would have to stop demanding equality”, Singer says.

Actually, this is one place where Singer went a bit too fast for me. Few people want to be caught saying that there are creatures with genuine interests that count for nothing; often, the strategy will rather be to deny the interest at stake. Even anti-suffragists argued that women should be withheld the vote not because their interests should be discounted, but because it was not in their interest at all.

“We think that justice and fairness consist, not in ignoring actual differences, but in so adjusting necessary burdens with due regard to the lines of irremovable difference as to secure the most even distribution of pressure. We believe that the fact that Nature has irrevocably imposed certain burdens on our sex constitutes a claim, as a matter of justice, that we should be relieved from some part of those functions which men are competent to share with us”,

wrote one anti-suffragist in 1907.[1] This would be a valid argument, if indeed the right to vote were primarily a burden, and domestic burdens were both natural and irremovable. That this is the opposite of true is a matter of fact rather than of value. The demand for political equality, then, is based on actual equality, not in the sense that every individual exercises their political rights with equal gusto, but in the sense that there are no significant differences between men and women that imply that one group has no genuine interest in the vote. In fact, we take neither individual capacities nor individual preferences into account when it comes to the distribution of political rights; else, based on how much I personally enjoy voting and how well I do it, I should be allowed to vote many times over in every election.

Singer does not want to extend the vote to animals: the point is that their interests should be taken into account. He is, of course, completely right about this, and my pushing back against his interpretation of equality among people does nothing to suggest otherwise. Still, I think the disanalogies with human liberation, and the ways in which animals are different from humans, are significant in more ways than the mere fact that they have different interests. They also involve the fact that animals can’t express their subjective interests in speech and writing, and that we humans are the only ones who can put those interests into language and reason about them. This is difficult, although not so difficult that there can be any doubt about whether factory farming harms the interests of the animals it exploits. It also means that the waters will be muddied only by humans: unlike the anti-suffragist writer I quoted above, no pig will sign its name under an argument to the effect that its own oppression is actually an instance of “justice and fairness”.

Animal testing

Taking up the task of figuring out which animals have interests and to what extent, Singer ends the first chapter with a survey of current scientific opinion about the capacities of different groups of animals to feel pleasure and pain. His conclusion is that for mammals and birds, this evidence is overwhelming, as it is for fish with bony skeletons (called teleosts). The latter “cannot yelp or whimper, and they do not have facial expressions that we can recognize as indicating distress”, but they do clearly feel it. There are also many sentient and intelligent invertebrates, such as octopuses, and the evidence is strong for decapod crustaceans. With insects, it is doubtful that their nervous systems are complex enough for subjective experience, but there is a serious case that they are. A recurring motif in Singer’s survey is that where there is little evidence for sentience or intelligence, there has often been less scientific effort to gather evidence either way.

Next come chapters on our current treatment of animals. First, the animals – between 100 and 200 million worldwide (annually) – used for testing. Singer warns that descriptions of experiments on animals will be disturbing, and this warning is justified. We learn of half a century of attempts to study mental illness by causing it in monkeys: frightening them while blocking off any possibility to escape; subjecting them to social isolation; taking them away from their mothers and giving them artificial substitutes for mothers that then deliberately hurt them in several ways; and so on. The list is forceful because the experiments described are designed to mess with the monkeys’ minds; they only work if the subjects really suffer and break down in ways similar to humans. If their minds are not like ours, Singer points out, “the experiments are unlikely to benefit us and there is less justification for funding and carrying them out.” If they are like ours, then we should consider how we would respond to similar experiments being carried out on humans.

This will remain the general argument when we are told about methods to induce post-traumatic stress disorder in dogs, rats, and other animals: exposing them to electric shocks, to the scent of predators, and holding them underwater has given us the insight that some rats are statistically more vulnerable to PTSD than humans. The difference doesn’t mean the rats are now off the hook; instead, researchers start controlling for more variables, such as genetic predisposition (for which they need to subject larger groups to stress) or stresses in early childhood (which can be delivered to young animals at will). To test the importance of social bonds in protecting against anxiety and depression, scientists put monogamous rodents in stressful situations with or without their partners, then decapitate them to section their brains.

After describing these psychological experiments, Singer moves on to the testing of  substances on animals. In the EU and Britain, these experiments run in the millions yearly, with several hundred thousands of them causing their subjects ‘moderate’ or ‘severe’ pain. For the US, Singer calculates an estimate of about 24 million animals, mostly for medical products. Among else, this means poisoning them to find out the toxicity of a substance. Since animals tend to sniff out poisonous substances and avoid ingesting them, they often have to be force-fed in a procedure which, in one dedicated study, by itself killed 15 percent of the mice subjected to it by accidentally perforating their esophagus. Singer points out that the nature of experiments aiming to find out the dosage that kills them precludes dying animals being put out of their misery.

Toxicity testing has improved; alternatives have been developed that avoid immense amounts of suffering already, but there are no completely adequate alternatives to all toxicity tests on animals. Singer notes that there is often a simple solution, which is to make the relatively small sacrifice of not bringing a substance on the market whose testing would lead to a lot of suffering and whose availability doesn’t really improve our lives all that much. His argument is that most ends don’t justify these means; it is not that every and all tests on animals are absolutely off-bounds. He admits that there may have been a case where the suffering of a hundred monkeys was justified because it led to medical insights that helped improve the condition of tens of thousands of people with Parkinson’s disease.

In the context of medical experiments, conceding this may feel like walking into a longtermist trap: anything that might reduce suffering in the long term and will do harm only in the short term has a net expected utility, and a lot of cruel psychological experiments might be back on the table if a plausible case can be made that they could improve our understanding of mental illness after all. However, Singer would probably point out that humans are not honest utilitarians, let alone honest longtermists. Our calculus is always warped by speciesism: our tendency to undervalue the interests of non-humans. We are careless with animals in ways that we are not with humans, and this leads us to allow them to suffer at much larger scales and with much less cause. When deciding whether the benefits outweigh the costs, we should check our prejudice, and consider how we would feel if similar experiments were performed on humans.

Factory farms

If the trade-off between scientific knowledge and animal welfare seems like it could lead to genuine dilemmas in theory (if not in practice, where Singer believes animal testing can realistically be put to an end), no such excuse exists for the practices that are the topic of the third chapter. Factory-farmed animals suffer and die in unfathomable numbers not for any high-minded purpose, but because most humans prefer to consume animal products over their alternatives.

When things go as planned, these animals lead a life of suffering and frustration, then die. When things do not go as planned, they die as well and suffer even more, as happens in the opening scene of the chapter: in 2020, US slaughterhouses were closed because of the Covid-19 pandemic, and veterinarians improvised a way to kill pigs in an alternative way. They did this by putting them into sealed barns several thousands at a time, then shutting off the ventilation and increasing the temperature to anywhere between 54 and 76 degrees Celsius. From there on, the “time to silent” was about 65 minutes (although infant pigs died slightly faster).

The practices enumerated in this chapter – almost all based on sources generated by the farm industry itself and by scientific experts – should speak for themselves, although Singer helpfully points out every now and then that they are made possible not by the exceptional cruelty of the people working in the industry, but by common speciesist biases that lead us to omit the interests of animals from consideration. Thus, chickens in broiler houses live in air rendered so corrosive by the ammonia in their droppings that they develop sores and blisters and may even go blind. That several percent of them – adding up to more than half a billion in the US in 2021 – die before they make it to the market is of course wasteful from an economic perspective, but it is still more efficient than allowing them to grow at a less dangerous rate. Singer counts the chickens that succumb prematurely as the lucky ones; their peers are in chronic pain for the last 20 percent of their lives, as their legs cannot support their weight, and sitting down would expose them to ammonia-laden litter causing burns on their bodies. When the chickens are slaughtered, they are required to be stunned, but as a too strong electric current may lower the quality of the meat, the commercial incentive is to lower the strength of the current, risking the birds to remain conscious while slaughtered or while being submerged in scalding water.

As an illustration of the case that commercial interests tend to trump animal welfare, this would clearly be sufficient; and were the book just an abstract argument, it could have been that much shorter. However, there are more types of animal lives to consider, and so we also get an impression of the lives of hens raised for laying eggs. “The idea that the hen is just an efficient way to turn feed into eggs isn’t good for hens, who are, unlike any machines we have invented so far, capable of feeling pleasure and pain”, Singer says matter-of-factly. Most facts about the plight of egg-laying hens are well known, but what was new information to me, is how strong the natural instinct of hens is to lay their eggs in a nest, away from other chickens. “Their instinctive reluctance to lay eggs amidst the crowd of their cagemates”, Singer quotes ethologist Konrad Lorenz, “is certainly as great as the one of civilized people to defecate in an analogous situation.” Singer refers to studies that found that hens will go through similar trouble to lay in a nest as they will to get food when they have not eaten for twenty hours. Perhaps this can count as an example of an experiment involving some animal suffering that may hopefully prove to be justified, if it contributes something to avoiding billions of years of suffering in the nearby future.

The laws of gravity

This was an extremely brief rendition of Singer’s already concise overview of the ways in which we make chickens miserable. In the remainder of the chapter, we still have turkeys, pigs, cows, and fish to go. It does not get better. The chapter ends with the description of methods that are commonly used in all but a handful countries for killing fish. An example is the use of salt to kill eels and loaches, in a long process during which the animals are conscious and vigorously struggling. “It’s painful […] but to make a delicious [loach soup], you have to give it some pain”, we hear a cook say. Singer adds, again with heroic matter-of-fact-ness: “you could, though, avoid causing the pain by instead eating a delicious vegan version of sundubu jjigae”.

So you could. In the next chapter, Singer makes the case that it helps to stop eating animal products. It helps rather straightforwardly, because individual consumer choices affect the economic calculus of producers directly. A plant-based diet saves roughly a hundred (vertebrate) animals yearly from the lives and deaths described in the previous chapter. That is to say, it has this expected value: supply chains are not so finely tuned that every single decision definitely makes a difference, but their ‘lumpiness’ has no impact on the expected outcome of our individual choices. There is a counteracting mechanism, however, in that a decline in demand lowers prices, which in turn increases consumption (by others). This effect has been studied and is calculated to be relatively modest: it lowers the expected decrease in the number of animals kept by roughly 10 to 40 percent.

Singer uses the chapter to answer a few common questions. He points out that plant-based diets use resources more efficiently than animal products by a large margin, and that they are better for the environment and the climate as well as for the animals. He also considers the case for being a conscientious omnivore rather than a vegetarian. When it comes to the question whether there are problems in principle with killing animals that have led happy lives, he concedes that it is a live option: “somewhat to my chagrin, I admit, I am unable to provide any decisive refutation of the conscientious omnivore”. However, it is extremely difficult to avoid significant suffering even under the best possible circumstances, and we should not kid ourselves about the actual circumstances; avoiding factory farmed products  – “the absolute minimum that anyone with the capacity to look beyond considerations of narrow self-interest should be able to accept” – is not easy given that, for example, more than 98 percent of pigs and chickens are kept in factory farms.

In practice, then, omnivores who are aware of the plight of (factory-farmed) animals live with a contradiction. “Their values and their food choices are not in harmony, and this discord must get repeated on a daily basis. That can’t be a good way to live.” Singer is an expert on Hegel, and knows that contradictions are there to be resolved. “My aim is to make the transition to plant-based eating easier and more attractive, so that instead of seeing the change of diet as a regrettable moral necessity, you will look forward to a new and interesting cuisine […].” Animal liberation contains not just principled philosophical arguments and moving descriptions of suffering animals; it also contains vegan recipes, a synthesis of the pleasant and the good.

The internal contradiction in the lives of omnivores mirrors our historical circumstances. For the medieval philosopher Thomas Aquinas, the suffering of animals was justified by a Christian Aristotelianism according to which lower beings existed to serve higher beings. With Descartes, the distinction between creatures with and without a soul was radicalized to the point where animals were not even thought capable of suffering. Now, in the modern era, the intellectual foundations of our worldview are altogether different. We have Bentham’s philosophical insight that everybody’s suffering counts, and we have Darwin’s insight in our place in the natural world to confirm that we are not the only genuinely sentient beings. We have, however, not stopped eating meat collectively; we have entered the “era of excuses” – of looking away or providing feeble rationalizations for practices that we know fundamentally to be unjustifiable. (The final chapter answers some of the more common rationalizations directly.) The foundations under speciecism have been knocked out from under it, but it just hangs there, “defying the logical equivalent of the laws of gravity.”

In this image of stubbornness and defiance there is an implicit prediction, made explicit towards the end of the book, that it has to come to an end; that we will eventually liberate ourselves from these old ideologies. There is a resolution to the conflicting theses of speciecism on the one hand and of modern philosophy and science on the other. We can think ourselves out of our habits, and live an examined life in which our ethics and our actions are once again in harmony. How long it will take, Singer does not know, “nor how many trillions of animals will continue to suffer until that happens. The way in which you and other readers respond to this book can shorten that time, and reduce that number.”


[1] Cited eagerly by A.V. Dicey in his Letters to a friend on votes for women, p. 64-65.