Thou shalt not kill - not even animals?

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Animals are different from humans, but there is no one difference and only some differences are morally relevant. Too many moral theories say "only one thing is relevant to how we treat others" and affirm that animals meet, or fail to meet, the relevant requiriement.

But life is more complicated, because there are scores of relevant considerations and the treatment of animals needs to be considered carefully case by case.

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Thou shalt not kill - not even animals?


Professor Richard Sorabji


How did the West get the idea that it is perfectly alright to kill animals? According to Genesis, the first book of the Bible, dominion over animals was granted to the first human couple, Adam and Eve, but that dominion did not extend to killing animals. Food was vegetarian. After Adam and Eve were expelled from the Garden of Eden, they were provided with animal skins, but it is not said that the animals were killed. In a later generation we hear that the animal sacrifice by Abel was preferred to the vegetarian sacrifice of his brother Cain. But it was later still, after the Flood, that God made a second covenant with Noah, who had rescued many animals, allowing humans not only to sacrifice, but also to eat animals.

An important influence came from the pagan side. The pagan Greek philosophers had an evenly matched debate on whether it was alright to kill animals. The most influential of the anti-animal views was that of the ancient Stoics, who started around 300 BC. They had a striking and in many ways a very humane view. All rational beings are bound together by bonds of attachment and owe each other justice. Since all humans are rational, justice is owed to foreigners and slaves. They criticised Aristotle's view of slavery and said there is no such thing as a natural slave. The view, which places a great stress on rationality, had a huge influence on European culture. In 1550-1, Charles V of Spain halted the conquest of the American Indians for a year, while his philosophers debated whether the Indians were in Aristotle's sense natural slaves, who could therefore be enslaved. I believe the debate turned not only on Aristotle, but also on Stoic views about the brotherhood of rational beings. In 1539, Francisco de Vitoria had described the American Indians in Stoic terms as citizens of 'the whole world which in a certain way constitutes a single republic'. And in the debate of 1550-1, Las Casas cited on the American Indian side Cicero On Laws Book 1, saying that 'All the peoples of the world are men, and there is only one definition of each and every man, and that is that he is rational'.

The downside of the Stoic view was that, in their opinion, no animals were rational, so none belonged to the community to which justice was owed and nothing you did to an animal could be an injustice. There are at least two things wrong with this premise that no animals are rational. First, in my view, it is untrue. To take the simple case of Wolfgang Kohler's chimpanzee, which put two sticks together to reach a banana, when it couldn't reach the banana with one stick, this was already an exercise of reason. There has been a long history of retreat from the criterion of rationality, and a rather desperate search for some human characteristic shared by no animals. Both the Stoics and modern writers have suggested that perhaps animals do not have syntax. The conclusion is meant to be, 'So we can eat them'. Actually, studies of chimpanzees and of the grey parrot suggest that even the syntax premise may still be untrue. But what is more striking is that it is irrelevant. For if it is true, nothing would follow about whether or not it would be alright to eat them.

As regards relevance, it is more appropriate to consider whether animals suffer. Their rationality would be relevant to this only insofar as rational beings may be capable of a wider range of suffering. It is surprising how late the question of suffering was deployed in the debate on whether it was alright to kill animals. That debate had been going on among the Greek philosophers for 800 years, when the Neoplatonist Porphyry finally pointed out the difference between eating vegetables and eating animals, that animals feel pain and terror. He may have been drawing on a lost work of Plutarch from 250 yers earlier. But even then the debate would already have been going on for 550 years.

St Augustine, a little after 400 AD, considers the Commandment, 'Thou shalt not kill' in the first Book of the City of God. He wants to deny exceptions. In the recent fall of Rome to the barbarian invaders, women had committed suicide to avoid rape. But 'Thou shalt not kill' mentions no exception for suicide, and Augustine will not allow it. Suddenly, however, in Book 1, Chapter 20, he makes an exception for killing animals. After all, Christ had been born into a community that ate meat and fish, and his disciples were fishermen, so it would be difficult to condemn. But how can it be shown that the commandment, 'Thou shalt not kill', allows this one exception? Augustine has nothing better to offer than the Stoic reason. Animals, he says are not rational and so do not belong in our community. This is the philosophical basis on which the Western tradition has reassured itself that killing animals was alright.

Yet Augustine was picking only one side from a much more evenly balanced Greek philosophical debate. He had read some works by the Neoplatonist Porphyry written a hundred years earlier, whether or not he had read Porphyry's On Abstinence from Killing Animals, recently re-translated by Gillian Clark. This short work, written just before the Empire became Christian, summarises the arguments that defended the killing of animals, and then makes the case against drawing once again on centuries of earlier argument. Among pagans, animal sacrifice and meat-eating had gone hand in hand. Porphyry argues in turn that a proper understanding of gods, of animals and of other human races which are vegetarian, would show that this policy was wrong. Particularly relevant is Book 3, which tackles head-on the injustice to animals, arguing convincingly that they are rational, and recognising that it is also relevant that they feel pain and terror.

A decisive shift away from the focus on animal rationality was made by two British philosophers in the 18th century, Hume and Bentham. Hume downgraded reason, saying that what is ordinarily called reasoning is merely an exercise of memory, which has set up in us a habit which makes us from something perceived expect its usual attendant, and animals have this habit, just like humans. More famously, he said that reason is and ought only to be the slave of the passions, which is usually taken to mean that morality depends on sympathy (shared by animals), not on reason. Bentham maintained that a dog or horse was rational, but shifted the ethical question by saying of animals, 'The question is not, can they reason? Nor, can they talk? But can they suffer? This was an expression of his Utilitarian ethics, according to which action should aim at the greatest happiness of the greatest number, and, since animals are capable of suffering, their happiness should be considered too.

n the 19th century, the German philosopher Schopenhauer, though conceding that animals lacked reason, still insisted that they had rights and applauded the English for having a unique sympathy for animals, in spite, as he said, of their religious beliefs. He particularly praises the establishment in England in 1839 of a Society for the Prevention of Cruelty to Animals. Later in 19th century England, Darwin, defending his evolutionary theory in The Descent of Man, further challenged the focus on reason by saying that there is no human psychological characteristic not shared to some degree by animals, although elsewhere in the book, he excepts language and the use of fire.

In recent times, a book of 1975 had an exceptional impact, Peter Singer's Animal Liberation, which in no way condones the violence of the English branch of the Animal Liberation Movement. This is a case of a modern Philosophy book having an impact on the economics of the meat industry and on practices in scientific and medical research. It would be hard for any reader not to be moved by the empirical chapters describing the treatment of animals in scientific research and in factory farming. Some of the factory farming practices have recently rebounded in this country to harm us ourselves. Yet while the book convinces that we must change our treatment of animals, the moral basis proposed for a new outlook is not to me persuasive. The moral basis, if I can say this without disrespect, has a one-dimensional character, in that only one thing is thought to matter: the satisfaction of preferences. Since animals have preferences, and preferences are the only consideration, their preferences should be considered on an equal footing with those of humans. Or if animals like molluscs do not really have preferences, then the quantity of pleasure and pain should be considered. This is a modern version of Bentham's Utilitarian theory.
Singer poses himself a test case. If we are really obliged to conduct medical or scientific experiments on living beings, we should be ready to do so on an orphaned imbecile with few preferences, rather than on a vivacious animal with many. For that will maximise preference-satisfaction. If animals are still chosen rather than imbeciles, he says, then we are guilty of speciesism, a term coined earlier by Richard Ryder in 1970, to draw a parallel with racism and sexism. Unfortunately, Singer pressed his case about human imbeciles, not merely as something so obviously wrong as to make us think again about animals. Extending his case to haemophiliacs and victims of Down's Syndrome, he advocated their killing at birth, if the parents intended to replace them with a happier child and there was no possibility of adoption. He thus became the centre of international controversy.
Another leading book, The Case for Animal Rights, published by Tom Regan in 1984, offers a different basis. Mammals, and probably many other animals, have rights as individuals not to be harmed, because of their inherent value, and their value is due to their rich mental life. Inherent value is said to admit of no degrees, and it in effect replaces preference-satisfaction as the one thing that matters. Regan seeks to exclude other considerations, so far as he can. He is concerned with individuals, even if it be at the expense of species. It is not a consideration that someone might be proposing to kill the last member of another species, in order to save an animal with inherent value. Saving species is not what matters, but protecting those individuals which have value.
Regan, like Singer, sets himself a test case, parallel to one which had also been used in antiquity against the Stoics. It is the case of a life raft. On this life raft we are to imagine that there are three humans and a dog, but there is not room for all four. Does Regan's principle of equal inherent value mean that lots should be drawn, and one of the humans possibly jettisoned instead of the dog? At this Regan demurs. Death, he says is a greater loss to a human than to a dog. This has the merit of letting in a second consideration. But is it always true? What if one of the humans is senile and the dog is bounding with life? Or what if one of the passengers is a Martian with a far richer life than our own? Singer adds that the consideration of greater loss would open the floodgates to medical experimentation on animals, since human death would, on this principle, be a greater loss than animal death.

I applaud the conclusion of these books that we must pay far more attention than we do to the welfare of animals. But I can now state my chief doubt about the moral basis offered for the conclusion. It is that the theories take only one main consideration into account, preference-satisfaction or inherent value, just as the ancient Stoics took into account only one factor, rationality. But life is more complex. Unfortunately, there is an indefinitely large number of considerations that may need to be taken into account, and there is no limit to how far we may need to expand our imaginations in order to recognise them.

As one consideration, one may want to say of Singer's orphaned imbecile that it has suffered a tragedy. But is there room for the idea of a tragedy in his theory? The idea of tragedy might also help to explain why we value human imbeciles who lack Regan's value-giving characteristics, a question he excludes as beyond the scope of his book. As regards Regan's life-raft, one wants to ask, 'Are some of the passengers members of one's family?' If there is a Martian on board, did he come as an intruder or a friend? Regan does in fact let in considerations of family ties and friendship after all. But there are many other considerations yet.

Mary Midgley, in her admirable book, Animals and Why They Matter, draws attention to special need and special responsibility: the fledgling fallen from its nest, the injured animal one has oneself run over. Suppose on my way home to celebrate my wife's birthday, I accidentally run into a pheasant and injure it. Shall I stop and see if I can help it? If we are to consider only preference satisfaction, my wife may have far stronger preferences about my not being late than any preferences of the pheasant. If we are to consider whether the mental life of the pheasant reaches the threshold for inherent value, the question may be unanswerable. But these are the wrong considerations. The point is that it was I who injured the bird, although that needs to be weighed against my wife's legitimate expectations, and we do not have the convenience of a single relevant dimension for assessment. Suppose the bird is not a pheasant, but a member of an endangered species, whose disappearance would remove some of the beauty from the world. That is a separate consideration.

The charge of speciesism has been mentioned, but here again Mary Midgley is helpful. She points out that race and gender do not provide a natural barrier in the way that species does. Witness the fact that some of the deepest human relationships cut right across race and gender. By contrast, we cannot cross the barrier of species so as to intermarry with animals, or have children, or farm children out for adoption. I think it is one legitimate consideration among others to prefer members of one's own species in cases where a choice has to be made. And in saying this, I am not necessarily favouring humans. For if we could interrelate in this intimate way to Martians, this would alter our duties towards them, and conversely if we could not, Martians would be entitled to eat us rather than each other, if that was necessary for their survival. Although I would do my utmost to avoid being eaten, I would not consider them unjust.

I will mention two outstanding issues before I leave the modern theories. First, Singer addresses the issue that without factory farming, many domestic species would die out. My own comment is that exactly the same defence might have been made of some forms of slavery, although in that case its unsoundness would nowadays be obvious. If we don't breed these slaves, it might have been said, their race will die out. Our thoughts about animals may be in much the same state as the ancient debate on slavery in Aristotle's time. Aristotle said that if shuttles could weave of their own accord, we wouldn't need slaves, but that possibility was then too remote for anyone to take seriously. Accordingly, Aristotle provided the theory that some people are wrongly enslaved, but others are natural slaves, better off with a master, because they are not able to plan their own lives. I am sure that Aristotle's premise was absolutely right that some people are not able to plan their own lives. But if his conclusion was right too, then I fear that many distinguished philosophers would be natural slaves.

Finally, I have a particular anxiety about Regan's theory, that, as he recognises, it does not afford protection to all animals. Moreover, the boundary separating off the species not protected by inherent value is made very sharp, by the view that inherent value does not admit of degrees. Since the mental capacities which provide inherent value surely do admit of degrees, it is a harsh result for those animals which fall just short of the threshold for inherent value that they are not protected.

But if I agree with the conclusion about the need for more concern for animals, but disagree with the theories mentioned, I can fairly be asked what I would put in their place. First, I would say what I offer need not be a theory. I am not talking to moral sceptics, but to moral people who have no wish to hurt their fellow human beings. So I can speak as follows: whatever protects our fellow humans (and I have no theory about what does protect them), the same should protect animals, to the extent that they do not differ in morally relevant ways. One task will then be to consider how various animal species do differ from us, and I would expect different answers for different species. But there will be the constraint that the differences we react to will need to be morally relevant. This rules out the possession or lack of syntax as a relevant difference, unless the lack of syntax could be shown to have morally relevant effects, such as exempting animals from experiencing depression from crowding in darkened sheds. It would be hard to show, however that lack of syntax freed them from depression. I deliberately mention differences rather than similarities, because no number of similarities between animals and humans would remove the suspicion that there is nonetheless some huge morally relevant difference. But it may be objected that I need to formulate a moral theory, in order to decide, for example, what differences are morally relevant. I do not think so. Any theory would be less certain and more disputable than the fact that syntax in itself is not morally relevant, whereas depression, the distress of long distance truck haulage, or fear induced by slaughterhouse procedures, is relevant.

Where we do not agree with each other about the moral relevance of something, one resort is to discuss our disagreement. It may seem wrong to us to leave domestic animals to die on the street, as we did with horses in the 19th century, and some other nations do now. But how do we avoid it? By euthanasia? Insofar as this is the answer, we may need to re-examine our grounds for denying euthanasia to humans who want it, while imposing it on domestic animals. Our own moral assessments are not immune from reflection. But of course disagreements may remain. And another resort, if there is no agreement on the moral relevance of one point, is to look for another point. Even then, disagreement may remain, especially if we are discussing with a society which, like Porphyry's, believes in animal sacrifice. But where disagreement persists, moral theory is not likely to resolve it. Believers in animal sacrifice are not going to agree with the theory that preference satisfaction, for example, is the only thing that matters. Philosophical argument proceeds by exploiting areas of agreement in other branches of Philosophy too. In ethics, the difference may only be that the issues are morally important.

The search for morally relevant differences is not all that is needed. Where morally relevant differences are agreed, there is still the question how great the differences are, and how important the purpose for which we propose to exploit or kill animals. Unfortunately, where the purpose is most serious, as for medical research, the animals that would forward that research may be those with the smallest differences from humans. And where the differences are large, the purpose, be it food or even cosmetics, may be less pressing. We must further ask whether the use of animals is necessary, or whether substitutes can be used. We must consider what is to count as harm, only suffering, as Bentham maintained, or also loss of life, as Aristotle's successor Theophrastus said, and as many people would say for the case of human lives. The list of considerations is indefinitely large.

I have been arguing for multiple considerations, rather than a unifying theory. But it may be objected that the belief in multiple considerations is itself a theory, and so it needs to be established first, before we consider how to treat animals. I disagree. I think the present order of discussion is the right one. The concrete case of animals makes clearer than an abstract discussion could why multiple considerations are needed.

What consequences would multiple considerations have for recent dilemmas about animals? I should confess at once that I am no saint. I have modified my diet, but when visiting, I eat whatever I am served. When choosing in private, I go no higher than fish. That is my weak compromise. I would not recommend vegetarianism to anyone who would go short of food or suffer ill health.

The country has recently had to consider foxhunting, foot and mouth disease, and medical research. A violent version of the animal support movement harmed the one thing which has considerable justification, in my view, when they recently attacked members of a medical research unit. Of course, medical researchers need to be under constraint not to be cruel, or needlessly wasteful of life, but medical research is a far more serious purpose than cuisine or styles of clothing. Fox hunting, in my view, should eventually be replaced by something else. I remember the hounds following scent trails on the Westmoreland fells, with no tearing apart of any quarry. But people certainly need to be given time to adapt their ways of life and I think that there has been a lack of proportion here. We have just killed over a million healthy farm animals for commercial reasons, in case they became infected with foot and mouth disease, having rejected the route of vaccination. This was hardest on the farmers, and I have explained why I think it is reasonable for humans to give special consideration to fellow humans. But in this case it does not look as if any consideration at all was given to animals, and they should surely count for something. It cannot have been better for them that over a million should be slaughtered and others caused to die by restrictions on pasture movements. If there is that little concern for animals, one cannot in the same breath express concern for foxes. Foxes are a pest to keepers of other animals, and so it is likely, in my view, that there would be justification for human culling, even if a less cruel method needs to be found. But all of us who eat animals and animal products are responsible for how farm animals are treated, so first we should consider more carefully how we as a country treat farm animals on a massive scale, before we direct a small group of people on how they should treat foxes. When we have put our own house in order, that will be the time to attend to cruelty to foxes.


© Richard Sorabji

This event was on Wed, 23 May 2001

professor richard sorabji fba

Professor Richard Sorabji FBA

Professor of Rhetoric

Professor Richard Sorabji was Professor of Philosophy at King's College London between 1970 and 2000. Before that he was an Associate Professor at Cornell University...

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