Peter Singer is now a Professor at Princeton University, USA. He was formerly Professor of Philosophy and Director of the Centre for Human Bioethics at Monash University, Melbourne, Australia. He is the author of Animal Liberation, which can be considered the Bible of the animal rights movement. Recently, he has been instrumental in the formation of the The Great Ape Project, which seeks to extend personhood and legal rights to the Geat Apes.
extracts from 'In Defence of Animals':
Why do we lock up chimpanzees in appalling primate research centres and use them in experiments that range from the uncomfortable to the agonising and lethal, yet would never think of doing the same to a retarded human being at a much lower mental level? The only possible answer is that the chimpanzee, no matter how bright, is not human, while the retarded human, no matter how dull, is.
This is speciesism, pure and simple, and it is as indefensible as the most blatant racism. There is no ethical basis for elevating membership of one particular species into a morally crucial characteristic. From an ethical point of view, we all stand on an equal footing -- whether we stand on two feet, or four, or none at all.
The animal liberation movement . . . is not saying that all lives are of equal worth or that all interests of humans and other animals are to be given equal weight, no matter what those interests may be. It is saying that where animals and humans have similar interests - we might take the interest in avoiding physical pain as an example, for it is an interest that humans clearly share with other animals - those interests are to be counted equally, with no automatic discount just because one of the beings is not human. A simple point, no doubt, hut nevertheless part of a far-reaching ethical revolution.
from The Expanding Circle:
The sphere of altruism has broadened from the family and tribe to the nation, race, and now to all human beings. The process should be extended ... to include all beings with interests, of whatever species. But we cannot simply propose this as the ultimate ethical standard and then expect everyone to act accordingly. We must begin to design our culture so that it encourages broader concerns without frustratiug important and relatively permanent human desires.

various extracts from 'Animal Liberation':
This book is about the tyranny of human over nonhuman animals. This tyranny has caused and today is still causing an amount of pain and suffering that can only be compared with that which resulted from the centuries of tyranny by white humans over black humans. The struggle against this tyranny is a struggle as important as any of the moral and social issues that have been fought over in recent years.
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. So the limit of sentience (using the term as a convenient if not strictly accurate shorthand for the capacity to suffer and/or experience enjoyment) is the only defensible boundary of concern for the interests of others. To mark this boundary by some other characteristic like intelligence or rationality would be to mark it in an arbitrary manner. Why not choose some other characteristic, like skin color?
The racist violates the principle of equality by giving greater weight to the interests of members of his own race when there is a clash between their interests and the interests of those of another race The sexist violates the principle of equality by favoring the interests of his own sex. Similarly the speciesist allows the interests of his own species to over ride the greater interests of members of other species. The pattern is identical in each case.
The practices discussed . . . involve . . . in one ease tens of millions of animals, and in the other case, literally billions of animals every year . . . we cannot pretend that we have nothing to do with these practices. One of them - experimentation on animals - is promoted by the government we elect, and largely paid for out of the taxes we pay. The other - rearing animals for food - is possible only because most people buy and eat the products of this practice. That is why I have chosen to discuss these particular forms of speciesism. They are the central ones. They cause more suffering to a greater number of animals than anything else that humans do. To stop them we must change the policies of our government, and we must change our own lives, to the extent of changing our diet. If these officially promoted and almost umversally accepted forms of speciesism can he abolished, abolition of the other speciesist practices cannot be far behind.
How can a man who is not a sadist spend his working day heating an unanesthetized dog to death, or driving a monkey into a lifelong depression, and then remove his white coat, wash his hands, and go home to dinner with his wife and children? How can taxpayers allow their money to be used to support experiments of this kind? And how can students go through a turbulent era of protest against injustice, discrimination, and oppression of all kinds, no matter how far from home, while ignoring the cruelties that are being carried out on their own campuses?
The answers to these questions stem from the unquestioned acceptance of speciesism. We tolerate cruelties inflicted on members of other species that would outrage us if performed on members of our own species. Speciesism allows researchers to regard the animals they experiment on as items of equipment, laboratory tools rather than living, suffering creatures. -Sometimes they even refer to the animals in this way. Robert White of the Cleveland Metropolitan General Hospital, who has performed numerous experiments involving the transplanting of heads of monkeys, and the keeping alive of monkey brains in fluid, outside the body, has said in an interview that:
Our main purpose here is to offer a laboratory tool: a monkey "model" in which and by which we can design new operative techniques for the brain.
And the reporter who conducted the interview and observed White's experiments found his experience
a rare and chilling glimpse into the cold, clinical world of the scientist, where the life of an animal has no meaning beyond the immediate purpose of experimentation. (Scope, Durban, S.A., 30.3.1973)
This "scientific" attitude to animals was exhibited to a large audience in December 1974 when the American public television network brought together Harvard philosopher Robert Nozick and three scientists whose work involves animals. The program was a follow-up to Fred Wiseman 's controversial film Primate, which had taken viewers inside the Yerkes Primate Center, a research center in Atlanta, Georgia. Nozick asked the scientists whether the fact that an experiment will kill hundreds of animals is ever regarded, by scientists, as a reason for not performing it. One of the scientists answered: "Not that 1 know of." Nozick pressed his question: "Don't the animals count at all?" Dr A. Perachio, of the Yerkes Center, replied: "Why should they?" While Dr D. Baltimore, of the Massachusetts Institute of Technology, added that he did not think that experimenting on animals raised a moral issue at all. ("The Price of Knowledge" broadcast in New York 12.12.1974.)
When are experiments on animals justified? Upon learning of the nature of many contemporary experiments, many people react by saying that all experiments on animals should be prohibited immediately. But if we make our demands as absolute as this, the experimenters have a ready reply: Would we be prepared to let thousands of humans die if they could be saved by a single experiment on a single animal?
This question is, of course, purely hypothetical. There never has been and there never could be a single experiment that saves thousands of lives. The way to reply to this hypothetical question is to pose another: Would the experimenter be prepared to carry out his experiment on a human orphan under six months old if that were the only way to save thousands of lives?
If the experimenter would not be prepared to use a human infant, then his readiness to use nonhurnan animals reveals an unjustifiable form of discrimination on the basis of species, since adult apes, monkeys, dogs, eats, rats, and other mammals are more aware of what is happening to them, more self-directing, and, so far as we can tell, at least as sensitive to pain as a human infant. Ibid.
At present scientists do not look for alternatives simply because they do not care enough about the animals they are using.
For most humans, especially those in modern urban and suburban communities, the most direct form of contact with nonhuman animals is at meal time: we eat them. This simple fact is the key to our attitudes to other animals, and also the key to what each one of us can do about changing these attitudes. The use and abuse of animals raised for food far exceeds, in sheer numbers of animals affected, any other kind of mistreatment. Hundreds of millions of cattle, pigs, and sheep are raised and slaughtered in the United States alone each year; and for poultry the figure is a staggering three billion. (That means that about 5,000 birds - mostly chickens - will have been slaughtered in the time it takes you to read this page.) It is here, on our dinner table and in our neighborhood supermarket or butcher's shop, that we are brought into direct touch with the most extensive exploitation of other species that has ever existed.
As a matter of strict logic, perhaps, there is no contradiction in taking an interest in animals on both compassionate and gastronomic grounds. If a person is opposed to the infliction of suffering on animals, but not to the painless killing of animals, he could consistently eat animals that had lived free of all suffering and been instantly, painlessly slaughtered. Yet practically and psychologically it is impossible to be consistent in one's concern for nonhuman animals while continuing to dine on them. If we are prepared to take the life of another being merely in order to satisfy our taste for a particular type of food, then that being is no more than a means to our end. In time we will come to regard pigs, cattle, and chickens as things for us to use, no matter how strong our compassion may be; and when we find that to continue to obtain supplies of the bodies of these animals at a price we are able to pay it is necessary to change their living conditions a little, we will be unlikely to regard these changes too critically. The factory farm is nothing more than the application of technology to the idea that animals are means to our ends. Our eating habits are dear to us and not easily altered. We have a strong interest in convincing ourselves that our concern for other animals does not require us to stop eating them. No one in the habit of eating an animal can be completely without bias in judging whether the conditions in which that animal is reared caused suffering.
The people who profit by exploiting large numbers of animals do not need our approval. They need our money. The purchase of the corpses of the animals they rear is the only support the factory farmers ask from the public. They will use intensive methods as long as they continue to receive this support; they will have the resources needed to fight reform politically; and they will be able to defend thcmselvcs against criticism with the reply that they are only providing the public with what it wants
Hence the need for each one of us to stop buying the produce of modern animal farming - even if we are not convinced that it would be wrong to eat animals that have lived pleasantly and died painlessly. Vegetarianism is a form of boycott. For most vegetarians the boycott is a permanent one, since once they have broken away from flesh-eating habits they can no longer approve of slaughtering animals in order to satisfy the trivial desires of their palates. But the moral obligation to boycott the meat available in butcher shops and supermarkets is just as inescapable for those who disapprove only of inflicting suffering, and not of killing. In recent years Americans have boycotted lettuce and grapes because the system under which those particular lettuces and grapes had been produced exploited farm laborers, not because lettuce and grapes can never be produced without exploitation. The same line of reasoning leads to boycotting meat. Until we boycott meat we are, each one of us, contributing to the continued existence, prosperity, and growth of factory farming and all the other cruel practices used in rearing animals for food.
It is at this point that the consequences of speciesism intrude directly into our lives, and we are forced to attest personally to the sincerity of our concern for nonhuman animals. Here we have an opportunity to do something, instead of merely talking and wishing the politicians would do something. It is easy to take a stand about a remote issue, but the speciesist, like the racist, reveals his true nature when the issue comes nearer home. To protest about bull-fighting in Spain or the slaughter of hahy seals in Canada while continuing to eat chickens that have spent their lives crammed into cages, or veal from calves that have been deprived of their mothers, their proper diet, and the freedom to lie do with their legs extended, is like denouncing apartheid South Africa while asking your neighbors not to sell the houses to blacks.
Vegetarianism brings with it a new relationship to food, plants, and nature. Flesh taints our meals. Disguise it as we may, the fact remains that the centerpiece of our dinner has come to us from the slaughterhouse, dripping blood Untreated and unrefrigerated, it soon begins to putrefy and stink. When we eat it, it sits heavily in our stomachs blocking our digestive processes until, days later, we struggle to excrete it. When we eat plants, food takes on a different quality We take from the earth food that is ready for us and does not fight against us as we take it. Without meat to deaden the palate there is an extra delight in fresh vegetables taken straight from the ground. Personally, I found the idea of picking my own dinner so satisfying that shortly after becoiming a vegetarian I began digging up part of our backyard and growing some of my own vegetables - something that I had never thought of doing previously, but which several of my vegetarian friends were also doing. In this way dropping: flesh-meat from my diet brought me into closer contact with plants, the soil, and the seasons.
All the arguments to prove man's superiority cannot shatter this hard fact: in suffering the animals are our equals.
Animal Liberation will require greater altruism on the part of human beings than any other liberation movement. The animals themselves are incapable of demanding their own liberation, or of protesting against their condition with votes, demonstrations, or bombs. Human beings have the power to continue to oppress other species forever, or until we make this planet unsuitable for living beings. Will our tyranny continue, proving that we really are the selfish tyrants that the most cynical of poets and philosophers have always said we are? Or will we rise to the challenge and prove our capacity for genuine altruism by ending our ruthless exploitation of the species in our power, not because we are forced to do so by rebels or terrorists, but because we recognize that our position is morally indefensible?
The way in which we answer this question depends on the way in which each one of us, individually, answers it.