We reproduce below the first two (short) chapters of an essay written by Peter Singer in 19851, which summarizes the ideas of animal equality and speciesism.


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“The question is not, can they reason?
nor, can they talk?
but, can they suffer?”

Jeremy Bentham


Let us start with some history, so that we can get some perspective on the animal liberation movement. Concern for animal suffering can be found in Hindu thought, and the Buddhist idea of compassion is a universal one, extending to animals as well as humans; but nothing similar is to be found in our Western traditions. There are a few laws indicating some awareness of animal welfare in the Old Testament, but nothing at all in the New, nor in mainstream Christianity for its first eighteen hundred years.

Paul scornfully rejected the thought that God might care about the welfare of oxen, and the incident of the Gadarene swine, in which Jesus is described as sending devils into a herd of pigs and making them drown themselves in the sea, is explained by Augustine as intended to teach us that we have no duties toward animals. This interpretation was accepted by Thomas Aquinas, who stated that the only possible objection to cruelty to animals was that it might lead to cruelty to humans – according to Aquinas there was nothing wrong in itself with making animals suffer. This became the official view of the Roman Catholic Church to such good – or bad – effect that as late as the middle of the nineteenth century, Pope Pius IX refused permission for the founding of a Society for the Prevention of Cruelty to Animals in Rome, on the ground that to grant permission would imply that human beings have duties to the lower creatures.

Even in England, which has a reputation for being dotty about animals, the first efforts to obtain legal protection for members of other species were made only 180 years ago. They were greeted with derision. The Times was so lacking in appreciation of the idea that the suffering of animals ought to he prevented, that it attacked proposed legislation that would stop the “sport” of bull-baiting. Said that august newspaper: “Whatever meddles with the private personal disposition of man’s time or property is tyranny.” Animals, clearly, were just property.

That was in 1800, and that bill was defeated. It took another twenty years to get the first anti-cruelty law onto the British statute-books. To give any consideration at all to the interest of animals was a significant step beyond the idea that the boundary of our species is also the boundary of morality. Yet the step was a restricted one, because it did not challenge our right to make whatever use we choose of other species. Only cruelty – causing pain when there was no reason for doing so, merely sheer sadism or callous indifference – was prohibited. The farmers who deprive their pigs of room to move does not offend against this concept of cruelty, for they are only doing what they think necessary to producing bacon. Similarly the scientists who poison a hundred rats in order to find the lethal dose of some new flavouring agent for toothpaste are not cruel – only concerned to follow the accepted procedures for testing for the safety of new products.

The nineteenth century anti-cruelty movement was built on the assumption that the interests of nonhuman animals deserve protection only when serious human interests are not at stake. Animals remained very clearly “lower creatures”; human beings were quite distinct from, and infinitely far above, all forms of animal life. Should our interests conflict with theirs, there could be no doubt about whose interests must be sacrificed: in all cases, it would be the interests of the animals that had to yield.

The significance of the new animal liberation movement is its challenge to this assumption. Animal liberationists have dared to question the right of our species to assume that human interests must always prevail. They have sought – absurd as it must sound as first – to extend such notions as equality and rights to nonhuman animals.


The case for animal equality

How plausible is this extension? Is it really possible to take seriously the slogan of Orwell’s Animal Farm: “All Animals are Equal”? The animal liberationists contend that it is; but in order to avoid hopelessly misunderstanding what they mean by this, we need to digress for a moment, to discuss the general ideal of equality.

It will be helpful to begin with the more familiar claim that all human beings are equal. When we say that all human beings, whatever their race, creed or sex are equal, what is it that we are asserting? Those who wish to defend a hierarchical, inegalitarian society have often pointed out that by whatever test we choose, it simply is not true that all humans are equal. Like it or not, we must face the fact that humans come in different shapes and sizes; they come with differing moral capacities, differing intellectual abilities, differing amounts of benevolent feeling and sensitivity to the needs of others, differing abilities to communicate effectively, and different capacities to experience pleasure and pain. In short, if the demand for equality were based on the actual equality of all human beings, we would have to stop demanding equality. It would be an unjustifiable demand.

Fortunately the case for upholding the equality of human beings does not depend on equality of intelligence, moral capacity, physical strength, or any other matters of fact of this kind. Equality is a moral ideal, not a simple assertion of fact. There is no logically compelling reason for assuming that a factual difference in ability between two people justifies any difference in the amount of consideration we give to satisfying their needs and interests. The principle of equality of human beings is not a description of an alleged actual equality: it is a prescription of how we should treat human beings.

Jeremy Bentham incorporated the essential basis or moral equality into his utilitarian system of ethics in the formula: “Each to count for one and none for more than one”. In other words, the interests of every being affected by an action are to be taken into account and given the same weight as the like interests of any other being.

It is an implication of this principle of equality that our concern for others ought not to depend on what they are like, or what abilities they possess – although precisely what this concern requires us to do may vary according to the characteristics of those affected by what we do. It is on this basis that the case against racism and the case against sexism must both ultimately rest; and it is in accordance with this principle that speciesism is also to be condemned. If possessing a higher degree of intelligence does not entitle one human being to use another for its own ends, how can it entitle human beings to exploit nonhuman beings?

Many philosophers have proposed the principle of equal consideration of interests in some form or other, as a basic moral principle; but not many of them have recognised that this principle applies to members of other species as well as to our own. Bentham was one of the few who did realise this. In a forward-looking passage, written at a time when black slaves in the British dominions were still being treated much as we now treat nonhuman animals, Bentham wrote:

“The day may come when the rest of the animal creation may acquire those rights which never could have been withholden from them but by the hand of tyranny. The French have already discovered that the blackness of the skin is no reason why a human being should be abandoned without redress to the caprice of a tormentor. It may one day come to be recognised that the number of the legs, the villosity of the skin, or the termination of the os sacrum, are reasons equally insufficient for abandoning a sensitive being to the same fate. What else is it that should trace the insuperable line? It is the faculty of reason, or perhaps the faculty of discourse? But a full-grown horse or dog is beyond comparison a more rational, as well as a more conversable animal, than an infant of a day, or a week, or even a month, old. But suppose they were otherwise, what would it avail? the question is not, Can they reason? nor Can they talk but, Can they suffer?”

In this passage Bentham points to the capacity for suffering as the vital characteristic that gives a being the right to equal consideration. The capacity for suffering – or more strictly, for suffering and/or enjoyment of happiness – is not just another characteristic like the capacity for language, or for higher mathematics. Bentham is not saying that those who try to mark “the insuperable line” that determines whether the interests of a being should be considered happen to have selected the wrong characteristic. The capacity for suffering and enjoying things is a pre-requisite for having interests at all, a condition that must be satisfied before we can speak of interests in any meaningful way. It would he nonsense to say that it was not in the interests of a stone to be kicked along the road by a child. A stone does not have interests because it cannot suffer. Nothing that we can do to it could possibly make any difference to its welfare. A mouse, on the other hand, does have an interest in not being tormented, because it will suffer if it is.

If a being suffers, there can be no moral justification for refusing to take that suffering into consideration. No matter what the nature of the being, the principle of equality requires that its suffering be counted equally with the like suffering – in so far as rough comparisons can be made – of any other being. If a being is not capable of suffering, or of experiencing enjoyment or happiness, there is nothing to be taken into account. This is why the limit of sentience (using the term as a convenient, if not strictly accurate, shorthand for the capacity to suffer or experience enjoyment or happiness) is the only defensible boundary of concern for the interests of others. To mark this boundary by some characteristic like intelligence or rationality would be to mark it in an arbitrary way. Why not choose some other characteristic, like skin colour?

Racists violate the principle of equality by giving greater weight to the interests of members of their own race, when there is a clash between their interests and the interests of those of another race. Similarly speciesists allow the interests of their own species to override the greater interests of members of other species.


Equal consideration of interests

If the case for animal equality is sound, what follows from it? It does not follow, of course, that animals ought to have all of the rights that we think humans ought to have – including, for instance, the right to vote. It is equality of consideration of interests, not equality of rights, that the case for animal equality seeks to establish. But what exactly does this mean, in practical terms? It needs to be spelled out a little.

If I give a horse a hard slap across its rump with my open hand, the horse may start, but presumably feels little pain. Its skin is thick enough to protect it against a mere slap. If I slap a baby in the same way, however, the baby will cry and presumably does feel pain, for its skin is more sensitive. So it is worse to slap a baby than a horse, if both slaps are administered with equal force. But there must be some kind of blow – I don’t know exactly what it would be, but perhaps a blow with a heavy stick – that would cause the horse as much pain as we cause a baby by slapping it with our hand. That is what I mean by the same amount of pain; and if we consider it wrong to inflict that much pain on a baby for no good reason then we must, unless we are speciesists, consider it equally wrong to inflict the same amount of pain on a horse for no good reason.

There are other differences between humans and animals that cause other complications. Normal adult human beings have mental capacities which will, in certain circumstances, lead them to suffer more than animals would in the same circumstances. If, for instance, we decided to perform extremely painful or lethal scientific experiments on normal adult humans, kidnapped at random from public parks for this purpose, every adult who entered a park would become fearful that he or she would be kidnapped. The resultant terror would be a form of suffering additional to the pain of the experiment.

The same experiments performed on nonhuman animals would cause less suffering since the animals would not have the anticipatory dread of being kidnapped and experimented upon. This does not mean, of course, that it would be right to perform the experiment on animals, but only that there is a reason, which is not speciesist, for preferring to use animals rather than normal adult humans, if the experiment is to be done at all. It should be noted, however that this same argument gives us a reason for preferring to use human infants – orphans perhaps – or retarded human beings for experiments, rather than adults, since infants and retarded human beings would also have no idea of what was going to happen to them.

So far as this argument is concerned nonhuman animals and infants and retarded human beings are in the same category; and if we use this argument to justify experiments on non human animals we have to ask ourselves whether we are also prepared to allow experiments on human infants and retarded adults; and if we make a distinction between animals and these humans, on what basis can we do it, other than a bare-faced – and morally indefensible – preference for members of our own species?

There are many areas in which the superior mental powers of normal adult human beings make a difference: anticipation, more detailed memory, greater knowledge of what is happening, and so on. Yet these differences do not all point to greater suffering on the part of the normal human being. Sometimes animals may suffer more because of their more limited understanding. If, for instance, we are taking prisoners in wartime we can explain to them that while they must submit to capture, search and confinement they will not otherwise be harmed and will be set free at the conclusion of hostilities. If we capture a wild animal, however, we cannot explain that we are not threatening its life. A wild animal cannot distinguish an attempt to overpower and confine from an attempt to kill; the one causes as much terror as the other.

It may be objected that comparisons of sufferings of different species are impossible to make, and that for this reason when the interests of animals and human beings clash the principle of equality gives no guidance. It is probably true that comparisons of suffering between members of different species cannot be made precisely, but precision is not essential. Even if we were to prevent the infliction of suffering on animals only when it is quite certain that the interests of human beings will not be affected, we would be forced to make radical changes in our treatment of animals that would involve our diet, the farming methods we use, experimental procedures in many fields of science, our approach to wildlife and to hunting, trapping and the wearing of furs, and areas of entertainment like circuses, rodeos, and zoos. As a result a vast amount of suffering would be avoided.


Peter Singer was Professor of Philosophy at Monash University, Melbourne, Australia, and is the author of Animal Liberation, first published in 1975. His other books relevant to this essay are Democracy and Disobedience (1973); Animal Factories (with Jim Mason, 1980) and In Defence of Animals, a collection of essays by philosophers, scientists and activists in the movement, which was published in 1985.



  1. The Animal Liberation Movement: its Philosophy, its Achievements, and its Future” by Peter Singer, originally published in 1985 by Old Hammond Press, England (text copyright: Peter Singer). We have not included the chapter on killing, as the author has changed his approach (from preference utilitarianism to hedonistic utilitarianism). The chapters following these first two seemed outdated to us and not very useful to include in the context of this site. The title “Animal Equality and Speciesism” is ours. A French translation was published in 2000 by éd. tahin party under the title “L’Égalité animale expliquée aux humain-es”.