Mention the philosopher and bioethics professor Peter Singer, and people tend to polarize into two groups: those who admire him for his position on animal rights, and those who despise him for his position on the rights of infants and the disabled. Reading Singer’s book The Ethics of What We Eat: Why Our Food Choices Matter (coauthored with Jim Mason) made me change to a vegetarian diet, which led to some arguments with friends who wanted to eat ethically but also ate meat. Our discussions, like Singer’s thinking, moved on to the larger question of humanity’s purpose on earth. What are our rights and responsibilities?

Singer is a world leader in the field of applied ethics. His ideas have shaped debate on animal welfare, medical ethics, economics, and philanthropy. He has a degree from Oxford and is the author or coauthor of more than twenty-five books. Time included him on a list of the top one hundred most influential people, and the International Academy of Humanism named him a humanist laureate. He’s a founder of the Monash University Centre for Human Bioethics and vice-president of the United Kingdom’s Royal Society for the Prevention of Cruelty to Animals.

Despite his acclaim and accomplishments, Singer has also attracted severe criticism. A New Yorker profile said, “Singer has never been afraid to take pure reason and drive it over a cliff.” At least two disability activists have called him “the most dangerous man in the world.” Protestors have disrupted conferences where he has spoken, and his speaking engagements have occasionally been canceled due to public outcry. He’s even received death threats.

What makes Singer controversial is his willingness to confront the most difficult questions about how to live an ethical life. In his 1975 book Animal Liberation: A New Ethics for Our Treatment of Animals, Singer argues against what he calls “speciesism” — the tendency to give more consideration to the interests of members of our own species than we give to the similar interests of beings of other species. Suffering is suffering, he says, no matter whose pain it might be, and so the decision to kill a being should be based on its level of self-awareness and its capacity to enjoy its life, not on its species. A healthy chimpanzee, in his opinion, might have more right to live than a severely disabled human infant. His views have led him to oppose the use of animal products, animal testing, and animal enslavement, and to support, in some instances, voluntary euthanasia, late-term abortion, and killing disabled infants. Singer’s detractors accuse him of promoting “eugenics.”

Singer arrived at his controversial beliefs through a school of thought called “utilitarianism,” which traces its roots to nineteenth-century philosophers Jeremy Bentham and John Stuart Mill. A utilitarian bases his or her actions not on a code that says whether the action itself is moral or immoral but on the prediction of the consequences — specifically whether the action will maximize the surplus of happiness for all those affected by it. Singer has modified the philosophy in two ways: he also takes into account the desires or “preferences” of the affected parties; and he includes nonhumans, who he says feel pain as much as humans do.

Currently a professor of bioethics at Princeton University and laureate professor at the University of Melbourne, Australia, Singer lives simply on both continents. Though his commitments to ethical living and to animal welfare resemble the Buddhist vow to end the suffering of all living beings, he holds no religious beliefs. He and his wife have been vegetarians since 1970 and contribute a significant portion of their income to charity. In his most recent book, The Life You Can Save: Acting Now to End World Poverty (, Singer urges everyone living above the poverty level to pledge a percentage of their income to organizations working against poverty. If you have bought a bottled beverage in the last week, he says, when drinkable tap water was available, then you can afford to help end human suffering.

I met Singer for this interview in his cell-like office in the oldest part of the University of Melbourne — a room so tucked away that it took me an hour to locate it. I was a little worried that he would say something about my leather shoes, but he didn’t comment. A tall man with an avuncular face, Singer was dressed in what looked like (but was not) a wool sweater, and his shoes were definitely not leather. As we spoke, he focused fully on our conversation, smiled very little, and didn’t joke at all. I never doubted that he treated seriously the ethical matters we discussed.


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Kendall: In philosophy circles you are often described as a “preference utilitarian.” What is that?

Singer: Let’s start with what it is to be utilitarian. A utilitarian judges actions as right or wrong in accordance with their consequences, so that an action that has the best consequences overall — for every being affected by it now and in the future — is the right thing to do. The utilitarian tradition says that when we are looking at consequences, we want to maximize happiness or pleasure and minimize pain or suffering. I think that is a little too narrow. I say we should understand good and bad consequences in terms of whether they thwart or fulfill the preferences of any beings affected. Of course since most sentient beings have a strong preference not to suffer pain and to enjoy their lives, there is a substantial degree of overlap between classical utilitarianism and preference utilitarianism.

Kendall: Is it sometimes hard to know what someone’s true preferences are?

Singer: Yes, just as it is hard to know what will make someone happy. Utilitarianism is a fairly rough-and-ready method. It will work where the differences are evident, but it will not tell you what to do when there are not enough facts to enable you to make a clear-cut decision.

Kendall: Even if a person states a preference, do you always trust that a person knows what he or she really wants?

Singer: Not really, no. People have to be fully informed and calm to make a choice. You have to make sure people aren’t uninformed or swayed by emotions.

Kendall: It’s difficult for a parent to rank his or her child’s preferences below the preferences of other beings. Do you have any advice for addressing this?

Singer: A parent should rank a child’s preference below that of others only if the preference is less important. For example, you should rank your child’s preference for the latest video game below the desire of another child to eat. To do that, you just have to put yourself in the shoes of the hungry child’s parents. But I am not asking parents to put their own child’s desire to eat beneath another child’s desire to eat.

Kendall: It might be difficult to convince some Americans that their teenager should go without a car so that a child in Africa might have healthcare.

Singer: The problem is that parents see other teens with cars, and they say, “Why shouldn’t my child have that too?” There are some decisions that are easier to make if we can make them collectively. Otherwise it is hard to break that reinforcing spiral of “These people do it; why shouldn’t I?”

Kendall: Is it a privileged position to be able to make choices based on how much suffering we might cause?

Singer: Yes, of course. We are in a privileged position in the West because we have resources to spare.

Kendall: What about a single mother with three kids and two jobs: do you think it’s feasible for her to, say, make her purchasing choices based on how much suffering might result from a particular product?

Singer: I think it depends on how well she can care for her children. If she is struggling to feed her children, I would expect her to give priority to that — although it is amazing how some poor people can find room to give to others. I don’t necessarily expect it, but it’s wonderful when it happens.

Kendall: You have said, “Food is an ethical issue — but you don’t have to be fanatical about it.” Please explain.

Singer: I was trying to draw a distinction between being ethical and being a purist. We should look at what we eat in terms of its consequences — that is, we should ask, “By eating this food, am I supporting practices that are cruel to animals, or damage the earth, or contribute unnecessarily to climate change, or hurt people in developing countries?” I think we should all ask those questions. But it is not like being an Orthodox Jew and keeping kosher. If I understand rightly, if you keep kosher, you do not eat certain foods under any circumstances. Eating ethically is not like that.

I judge things by their consequences. I don’t think you have to be pure. Most people are not doing absolutely everything right. And even if they are right in how they eat, what are they doing to help the world’s poor? I don’t know anyone who can claim to be a saint. We should not be too hard on others or on ourselves, as long as we’re doing what we can to reduce our harmful impact.

Kendall: So is it more important to produce social change than to be personally pure yourself?

Singer: Yes. You could make sure that no animal product ever crosses your lips or touches your body but be doing less than someone who might occasionally buy some humane animal products but is putting a lot of time and effort into helping animal-rights groups, or preventing climate change, or helping the world’s poor. The second person is having a bigger impact on the world, even though he or she may not be quite as pure.

Kendall: Many people look to you for guidance on how to eat ethically. How do you manage that role?

Singer: I can only talk about general principles and draw attention to particular issues. I cannot make a decision for anyone. People have individual needs and circumstances. I have to respect the choices that they make, as long as I believe they have conscientiously reflected on their actions and are trying to minimize the harm that they are causing through what they eat.

Kendall: I became a vegetarian by eliminating one kind of meat at a time. As I was doing that, I asked a Buddhist monk whether it was preferable to eat beef, where the death of one animal provides many meals, or fish, in which case it might take many deaths to create one meal. He answered that all animal lives are equal, and the death of even one tiny fish was no more or less regrettable than that of a cow. Do you agree?

Singer: No, I don’t agree that all animals are equal. I think that the seriousness of the harm you do when you kill a being depends on the kind of being it is. The more aware of its life the being is, the greater capacity it has for suffering, and the greater the possibility of its having desires for the future. I would certainly think it is worse to kill a chimpanzee than a shrimp, because of the greater awareness of the chimpanzee.

We must also take into account how an animal was raised. It is better to eat pasture-raised beef, because the animal has had a better life, than it is to eat chicken that has been factory reared. And we have to be aware of our impact on the environment — particularly our contribution to climate change. Unfortunately beef cattle produce methane through their digestive process, and grass-fed cows produce slightly more methane. So it goes beyond the question “How much suffering am I inflicting on animals?”

Kendall: Have you heard about the “animal-welfare rating standards” that Whole Foods is devising?

Singer: I don’t know the details, but I understand it is an effort to encourage producers to have more-humane, animal-friendly standards of production and to inform shoppers what standard the producer has reached. There will be very few products that actually reach the top standard at first, but hopefully some will move toward it, and consumers will be better informed. If people tend to buy the higher-rated products, it will provide incentives for producers to treat their animals more humanely.

Kendall: You don’t automatically see local food as better. In fact, you’ve said, “There’s a certain amount of double talk about local food that’s just too rosy.”

Singer: I think simply setting some arbitrary distance as the limit one’s food can travel, such as within a hundred-mile radius of where one lives, doesn’t make a lot of sense, because so much will depend on the climate and conditions where you live, and some of those local products may have more adverse environmental impact than products you could have bought from farther away. An example I give in The Ethics of What We Eat is that if you live in Boston and buy locally grown tomatoes in June, those tomatoes were grown in a heated greenhouse, but if the tomatoes had been grown in Florida without any heat other than the sun and trucked to Boston, the carbon emissions of the Floridian tomatoes would probably have been the same as or less than those grown locally. Or, for example, if you live in California, it’s probably better to buy rice grown in Bangladesh than local rice, because the imported rice is produced in a way that is more sustainable. Sometimes we buy fairly traded goods from foreign countries as a way to help the world’s poor. If the product is flown over to the U.S., the creation of greenhouse gases might outweigh the benefit to the poor, but if it’s brought by ship, which is more efficient, the fair-trade goods could be a better choice.

Kendall: If a person, after honest deliberation and reflection, felt that it was OK to catch, kill, and eat fish, would you attempt to change that person’s mind?

Singer: If that was the only kind of animal they were eating, and if they killed the fish humanely, as quickly as possible, and so on, then they would be way ahead of most people. Their choice might not be my choice, but I could understand how they could make it.

Kendall: Is it possible to have a “good farm,” where animals are well treated and are slaughtered without suffering?

Singer: It is possible, but it is harder than people think, and many of the farms that get praised for being humane are not. A big problem is that there are regulations about the slaughtering of animals when you are selling the meat, which means that on-site slaughter is often not possible if you want the animal to go to market; you are going to have to truck the animals to a slaughterhouse and have them killed. Maybe it’s possible for producers to go with the animals and see how they are treated and keep control of it, but I suspect few people actually do that. So my answer would be yes, it may be possible, but unless you are just raising the meat for yourself, it is pretty hard to do. When you talk about producing meat in the quantities that Westerners consume it, I think the answer is clearly no, we cannot do it ethically on that scale.

If you add sustainability as a criterion, it becomes even more difficult. All ruminants, such as sheep and cattle, are methane producers, and that is a pretty serious greenhouse gas. Chickens do not produce methane and are reasonably efficient converters of grain, but you are always losing some of the food value of the grain when you process it through a chicken and turn it into meat.

People have individual needs and circumstances. I have to respect the choices that they make, as long as I believe they have conscientiously reflected on their actions and are trying to minimize the harm that they are causing through what they eat.

Kendall: When it comes to eating meat, do you take into account the pleasure the steak gives to the diner, or is enjoying a steak secondary to the ethical issues involved in killing a cow?

Singer: Pleasure is part of the overall equation when deciding whether something is right or wrong, but I cannot see that the pleasure the steak eater gets is going to outweigh the loss to the animal. If it were a question of survival for a tribal people living in arid grasslands, where the only way they could get enough to eat would be to raise cattle, then that would be a different matter. But if we are talking about people who have choices about what to eat, then I would say you cannot compare the rather minor interest of human pleasure to the major interest of the animal’s life.

Kendall: Is there any ethical way to consume meat?

Singer: I have met a couple of people who eat roadkill. That is perfectly ethical. If a deer has been hit by a car and is lying dead by the side of the road, and you want to eat it, I have no objection to that.

Some “freegans” argue that any food, even meat, that you take from a supermarket dumpster is ethical, because it has been thrown away, so eating it does not support the meat industry. I find it hard to criticize that, if that is the only kind of animal products that they eat. But it’s not a terribly appealing option for most people.

Kendall: If “test-tube” meat — meat cells grown in vitro — were to become commercially available, would you eat it?

Singer: I would not have any problem with that if it were grown in an environmentally sustainable way. But the fact is that I don’t really miss meat. I have not eaten it in thirty-five years.

Kendall: Some people, like me, wear leather shoes on the grounds that leather is only a byproduct of the meat industry. How do you feel about that?

Singer: I don’t agree with it. I think the economic viability of the meat industry depends on the dollar return that producers get from the animals. I have no idea what percentage of the return comes from selling the leather, but it all contributes to profits, if only in a trivial way, so I do not go along with the “byproduct” distinction.

Kendall: What about insects? Do they feel pain? If not, is it OK to eat them?

Singer: There are gradations of certainty about animal suffering. It’s very clear that chimps feel pain, and equally clear that plants don’t. We can say with reasonable confidence that all vertebrates suffer, because they respond to stimuli in the same way that humans do when we are in pain. With invertebrates, it’s harder to know, although certainly they can be intelligent. Octopuses, for example, have shown remarkable abilities to solve novel problems. So I assume they are conscious and therefore can suffer.

I don’t know whether insects can suffer. In some ways their behavior is more rigid and mechanical, and perhaps can be explained without invoking consciousness. Insects do exhibit behavior that would appear to indicate a certain degree of social awareness. For instance, some ants will remove from their nests the decomposing bodies of dead ants, as if acting for the welfare of the group. But it turns out that a dead ant’s body emits a certain chemical that the living ants can smell, and they are responding only to that. If you dab a bit of the chemical onto the back of a living ant, the others will pick it up and carry it out of the nest, regardless of the fact that it is clearly still alive and wriggling. So they seem to be responding mechanically in that case. I would give insects the benefit of the doubt wherever possible, but I would not assert that they can feel pain.

Kendall: If they don’t feel pain, does that make insects an ethical choice as food?

Singer: Not if we have alternatives. But when we have to defend our own food supplies from them, we can justifiably kill them, if we have no better option.

Kendall: There seems to be evidence that plants are at least somewhat responsive to stimuli. Do you think it’s possible that plants suffer or feel pain?

Singer: No. Pain is an evolutionary development that is useful in enabling animals to escape harm. It is difficult to see why plants would have evolved a capacity to feel pain, since they are unable to move away from a source of pain.

Kendall: What do you think about groups such as PETA, Earth First!, and Sea Shepherd that destroy property and possibly endanger human life in their attempts to protect animals?

Singer: So far as I know, PETA has not been involved in any such activities, though I think they might have supported some people who were. And I think Captain Paul Watson of Sea Shepherd makes sure that he doesn’t endanger human life, although his organization might destroy property in its mission to stop illegal whaling. If the only way to save whales is to destroy or damage property, and if it is done with no threat to animal or human life, I might be willing to support it.

In the case of practices like tree spiking, which has been done by groups like Earth First!, I think they usually give loggers fair warning that some trees have been spiked. Of course there is still a danger that the trees will end up in a sawmill and will cause damage to machinery and injury to humans. I don’t support that.

Kendall: I recently was sent an online petition that contained a video about the skinning of live animals in China for fur. I was, I’m ashamed to admit, so upset that I neglected even to act on the petition. Similarly I was too distressed to read some sections of Animal Liberation, and I have friends who refuse to read the book because they know it will upset them. Is there a danger that potential activists and supporters will become paralyzed or even alienated by grief, shock, or guilt?

Singer: I can certainly understand people hating to see that kind of suffering, but we have to be able to spread the message. Now, maybe you do not want to see the most gruesome footage, such as that Chinese video, but how are we going to stop these practices if we can’t let people know about them? Normally people would ask why they should be concerned about animal suffering in China; there is enough suffering here. But if we can show them how extreme the suffering is in China, maybe we can convince them it is worth trying to stop it.

I do not, however, present shocking images to my students. They are a captive audience, and I think that would be wrong. I might tell them where a video is, but I do not tell them that they have to watch it.

We can say with reasonable confidence that all vertebrates suffer, because they respond to stimuli in the same way that humans do when we are in pain.

Kendall: What was your reaction to the video?

Singer: I agree it was very disturbing — and I am not an emotional person. I think that is why I was able to do the research for the book: I am reasonably in control of my emotions most of the time. But that was totally horrible, and it did make me want to do something about it. I have been in touch with some Chinese activists. There is a tiny animal-rights movement in China, and they need our support.

Kendall: Do you think signing an online petition does any good at all?

Singer: Probably not. We need people to boycott the fur industry or at least get fur stores to stop selling Chinese fur. China has become a huge fur producer, though it never was before. If the Chinese realize that their exports are imperiled by revelations about how their fur industry operates, they might clean up their act.

Kendall: Do you see progress in the area of animal rights?

Singer: Yes, there has been more regulation of animal experimentation in Europe and North America, and some in Australia as well. The European Union is also phasing out a lot of terrible factory-farming practices. So that is encouraging.

The danger is that the growth of meat production in countries like China, as they become more prosperous, will offset the progress we have achieved. That is why it is so important that we tell the Chinese, “Look, we went down this wrong road; it was wrong in environmental terms, wrong in terms of feeding the world, wrong in health terms, and terribly wrong in terms of animal suffering. You should not follow our lead.”

Kendall: Do you feel it is justifiable for us to tell other countries what they ought to do?

Singer: Yes, I am not a cultural relativist. Where we can see that what they are doing is causing unnecessary suffering, we are justified in pointing it out and trying to get them to change.

Kendall: What is the hardest part of getting people to listen to your ideas?

Singer: I suppose the hardest part is that some people really just don’t care enough to listen. They enjoy eating chicken or whatever, and they do not want to know any more about it — not so much because it is going to emotionally tear them up as because they do not care about chickens.

Kendall: On what topic do you encounter the most resistance to your ideas?

Singer: That would undoubtedly be on the issues of abortion and euthanasia. The opposition is sometimes based on a highly distorted reading of my views, or maybe no reading at all. Some people have heard that I think it is OK to kill disabled babies at birth, and that is all they need to know about it; they do not want to discuss in any detail why that might be the best thing to do in certain tragic circumstances.

Kendall: For the record, could you briefly state your views on abortion?

Singer: I do not think that abortion is wrong — at least, up to the point at which the fetus is capable of feeling pain, which I don’t think could be earlier than twenty weeks of gestation. The overwhelming majority of abortions are performed much earlier than that, so I see nothing wrong with them. It should be entirely up to the woman whether she wishes to complete the pregnancy or not.

Once the fetus is capable of feeling pain, it does not mean that abortion is necessarily wrong, but it does mean the suffering of the fetus must be considered, and there would need to be a good reason for the abortion, and steps should be taken to ensure that the fetus does not feel pain, such as providing anesthetic and choosing a method of killing that is as painless as possible.

Kendall: How about euthanasia? When is it ethical?

Singer: You have to distinguish between voluntary euthanasia, where the patient has given consent, and nonvoluntary, where there is no possibility of consent: for example, with an infant. I think voluntary euthanasia is relatively easy to justify when you have an informed, competent patient who is terminally or incurably ill and wants to die. It is now legal in the Netherlands, Belgium, and Luxembourg, and so is physician-assisted suicide in some U.S. states.

Nonvoluntary euthanasia is more difficult. It depends on a range of issues, including the person’s quality of life and the burden that caring for the person places on others. If we’re talking about an infant, for example, it’s important to know whether there might be another couple who would like to adopt the child.

Because infants are not fully self-aware immediately after birth, I do not think they have the same right to life as a creature that is fully aware. Awareness is something that develops over time. If, in the infant’s first month or so, the prospects for quality of life are poor, and the child is going to be too difficult to care for, it may be better that it does not live. That could be a defensible position. Obviously if you believe in the sanctity of human life from birth, you have a different view. My views about euthanasia for infants probably go against the grain, but I think there is wider support for them than people are prepared to admit. Many disabled infants are simply allowed to die, when lifesaving technologies are available. I see no difference between this and euthanizing them, except that euthanasia is probably less painful for the infant. And of course fetuses are often aborted if Down syndrome or spina bifida is detected.

Kendall: In cases of voluntary euthanasia, do you distinguish between someone who wants to die to avoid pain and a person who is depressed or doesn’t want to burden his or her family?

Singer: If you are talking about someone who is clinically depressed, you certainly want to try to treat the depression. If you have tried for several years to treat the depression with all available resources, to no avail, and the person continues to want to die, maybe the person should be allowed to die. But it has to be proven that the condition is incurable.

If a person is worried about being a burden on the family, I think that is really his or her decision. Let’s say you are elderly, and your quality of life is rather poor and is not going to get any better. I think there is nothing unreasonable about your not wanting to be a burden on your family. Parents tend to make a lot of sacrifices for their children. They may work in unhealthy conditions for long hours to send a child to college. Imagine if you did that, and now your child has been through college and is on the verge of having a successful career, and then you fall ill, and your child quits working to look after you. You might decide you don’t want to stand in the way of your son or daughter having a career. I don’t see why we should not respect that decision.

Kendall: Should a person in a vegetative coma be accorded fewer rights than a fully aware chimpanzee?

Singer: I tend not to talk about “rights,” so I do not think it is accurate to say anyone should be accorded fewer or more of them. There are complications with humans in a persistent vegetative state: Do they have relatives? What do the relatives want for them? Have we made sure that the person has no prospect of recovering? If you are quite sure the patient will never recover consciousness, and there are no loved ones who think it is important that the person be kept alive, then yes, I would say that there is less value in the rest of that person’s life than there is in the life of a healthy, aware chimpanzee.

Kendall: When I told a friend of mine, who uses a wheelchair, that I was going to interview you, she wrote, “Ask him why he thinks the lives of disabled people have no value.”

Singer: The answer is: “He doesn’t think that.” Some people think that because I support euthanasia for severely disabled newborns, I believe people with disabilities do not have lives worth living or should not be protected. But I would never suggest that people in wheelchairs aren’t capable of choosing whether to go on living or not. Disabled newborns, on the other hand, are completely incapable of considering what sort of life might be in store for them and whether they would choose to live it.

Kendall: What do you think about the death penalty?

Singer: If it is true that the death penalty is not an effective deterrent — and studies seem to suggest it isn’t — then we probably should not have the death penalty. If the death penalty were a uniquely effective deterrent, so that for every person executed we could predict that two people would not be murdered, then it would be a different situation.

It also depends on how good your criminal-justice system is, and whether innocent people are being executed, as clearly does happen in the United States. So there are a lot of considerations there. I don’t think it is an absolutist issue where you can say, “The death penalty is wrong,” independent of the facts.

Some people think that because I support euthanasia for severely disabled newborns, I believe people with disabilities do not have lives worth living or should not be protected. But I would never suggest that people in wheelchairs aren’t capable of choosing whether to go on living or not.

Kendall: Could you make an argument for the death penalty being beneficial if it relieved the suffering of the murder victim’s family?

Singer: Yes, though I think that is a cultural matter. In the United States I often hear that the death penalty brings “closure” to the relatives, who feel better when the murderer is executed. In Australia, where there is no death penalty, you don’t hear people say that. My sense is that Americans would stop saying this if they did not have the death penalty.

Kendall: Is there a place for punishment in a philosophy designed to avoid suffering?

Singer: Sure, but the utilitarian theory of punishment is not that anyone is intrinsically deserving of punishment, but rather that punishment may prevent further crimes. A person who is incarcerated can’t rob houses, for example.

Kendall: You’ve been attacked for statements you made more than thirty years ago. Are there some things you regret having said?

Singer: I don’t regret what I have written. I made some changes in the second edition of Animal Liberation, and now I am working on the third edition of Practical Ethics and making some changes there too. But I have not rejected the core arguments.

Kendall: What parts of the books are you changing?

Singer: There are some things I’ve written about euthanasia for infants with disabilities that I could have put differently. And the language has changed over the years. In the 1970s people talked about “defective” infants, and now that tends to be quoted against me, as if I were using it today, when I have not used that term since the 1970s. Some of my facts about the abilities of children with Down syndrome were not entirely accurate, because new studies have disproved them. In some instances what I wrote has been widely misunderstood and needed to be put differently.

One change that is philosophically significant is the question of whether, when you kill an animal that is having a good life, you can justify it by the fact that other animals will come into existence because we kill this one. In other words, because the farmer can get money for the bacon, he will raise more pigs. And if he does it in a way that the pigs have a good life, then there is an argument that you are not really harming the pigs as a group, and, anyway, the pigs would not have existed if people did not eat them. In the first edition of Animal Liberation I rejected that in a fairly dismissive way, but I now think that rejection was not justified, and the question isn’t so easy to dismiss.

Kendall: Of all the ethical choices you’ve made for yourself, which have been the most difficult for you?

Singer: Probably the most difficult was when my wife and I made the decision to become vegetarians in the 1970s. It was a peculiar thing to do back then. You were putting yourself into a fringe group. I didn’t know any other vegetarians except for the ones who had led me to my decision to stop eating meat. But I’d been quite appalled when I’d learned how animals are treated on factory farms, and I just could not go on supporting that.

Kendall: Are there parts of your life that you feel in conflict about?

Singer: Yes, there is still constant conflict about buying things that I do not really need when I could be giving the money away. We go on vacations with the kids, and I suppose we could send that money to a charitable organization instead, but those vacations are fairly important to me, and I already give a lot.

Kendall: When you are working out how much money to give away, do you take into consideration the hardship it will impose on you?

Singer: Hardship is too strong a word, but we do take into account how much we need to do the things that are really important to us.

Kendall: You have set the bar pretty high for giving to charity: around 25 percent of your income. Do you recommend that others donate that much?

Singer: I suggest a lower percentage for everyone except the very wealthy. I could still sacrifice some comforts and give more, and I am sure the money would do someone else lots more good. My rate of giving is high compared to most, but it is not high compared to where I could imagine it being, and where maybe it should be.

When you give money, you should start gradually and work your way up. Don’t cause yourself great hardship straight off, but give a modest percentage, so that you are still able to do most of what you want to do. Then you can work up gradually from there.

People who give tend to be happier and more content than people who don’t. Generosity makes life more meaningful and satisfying. For some people it just brings joy. There is evidence that it activates the pleasure centers of the brain, the same parts that are activated during sex.

Kendall: Do you ever find it difficult to give as much as you do to charity?

Singer: No, I can’t say that I do. I still have quite a lot. It might be harder for someone who is really giving to the point that it hurts. It helps that I have a tendency not to accumulate possessions. There’s a part of us that says, “I need this or that.” Another part of me answers, “Well, do you really? How much of a difference does it make?”

Kendall: Do you feel that all of us living in the West are inherently doing harm just by being consumers?

Singer: Yes. Obviously we have to live, but virtually every Westerner is contributing more than his or her fair share to climate change, which means we are inflicting harm on people in developing countries who are less able to defend themselves against it — people whose crops will fail because the rains won’t come or whose land will get flooded because the sea levels will rise. So, with the exception of a small number of us, we are contributing vastly more than we should to the carbon dioxide in the atmosphere.

Kendall: Is overpopulation the primary cause of hunger, or is it the unequal distribution of food?

Singer: At the moment the problem is distribution. We use, I think, 700 or 800 million tons of grain each year just to feed animals. So there is plenty of food to feed the world now, but there will not be if the population continues to rise. In the long term, overpopulation is a problem we need to tackle.

Kendall: Do we have an obligation to feed starving people in other countries if, as a consequence, there will be a population increase and thus more starving people?

Singer: No, if that is the consequence, we don’t have the obligation to feed them. But I am not advocating just feeding people. I am advocating educating people and helping them become self-sustaining. If you do that — particularly if you educate girls — you reduce birthrates. So we should focus our aid efforts on methods that are likely to reduce the world’s population in the long run, if not immediately.

Kendall: Are you an atheist?

Singer: Yes, because I cannot believe that an all-powerful benevolent being could allow the sort of world that we live in to exist. There is too much unnecessary suffering. Christians talk about people deserving to suffer or say we are descended from Adam and are suffering because of Eve’s sin. I think that is nonsense, but even if it were true, why would animals suffer? And then they say, “Humans have free will,” but humans and animals both suffer from disasters that have nothing to do with free will, like droughts and floods. It does not make sense that the kind of God Christians believe in would have created or allowed such a world to exist. Now, there could be some other supreme being who is all good but not all powerful, or vice versa, but I don’t see any reason to believe that either.

Kendall: The concept of karma says it benefits us spiritually to refrain from harming other beings. Do you believe that a utilitarian approach is in our own self-interest?

Singer: I do not believe in karma, but I do believe it is often in our own interest to act altruistically. Many people say that giving is the most rewarding and fulfilling thing they have done, and there is evidence that people who give tend to be happier and more content than people who don’t. Generosity makes life more meaningful and satisfying. For some people it just brings joy. There is evidence that it activates the pleasure centers of the brain, the same parts that are activated during sex.

Kendall: Your grandparents were in Nazi concentration camps, and your mother had Alzheimer’s. Is there some correlation between the amount of suffering in your family and your work as an ethicist?

Singer: Certainly it has nothing to do with my mother, because the basic outlines of my work were written long before she became ill.

Some people have said that my sensitivity to suffering may be a result of growing up knowing that three of my four grandparents died in the Holocaust. I do not know how to evaluate that claim. I am what I am, and I am sure that my circumstances played a part in it. But I never consciously thought, My family suffered greatly; I must try to prevent further suffering.

Kendall: What did lead you to work to end suffering?

Singer: I never really committed myself to ending suffering. I became aware of the issue of animal suffering because I had lunch with someone who was a vegetarian, and I started asking him questions. No one was writing about animal rights at the time. I thought the subject clearly needed more attention.

Kendall: You say you base your positions on the consequences of our actions, but our actions sometimes have unforeseen consequences and cause ripples too complicated to fathom. Is there no place for intuition or spiritual guidance when making decisions?

Singer: When it comes to a guide for our actions, I don’t think we can do better than our knowledge and intellect. If you can give me evidence that acting on intuition has better results than acting on reasoning and knowledge, I would evaluate the evidence using reason and knowledge. And if the evidence were good, then I would recommend that we act on our intuition. But I would, of course, then be acting on reason and knowledge.