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My guest today, Peter Singer, is arguably the most influential living philosopher. His thinking has had a profound impact on how the world views morality, animal rights, and philanthropy.

SINGER: I enjoy arguing and so I could have been a lawyer, but I think I found a field in which I can argue much more broadly about a wide range of topics. And I do think that I’ve had an impact on people.

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Welcome to People I (Mostly) Admire, with Steve Levitt.

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Peter Singer knows how to get people to take action. I, personally, know at least a dozen people who became vegetarian after they read his book Animal Liberation. And the effective altruism movement is in large part the consequence of his early writings on the topic. I’ve read a lot of what he’s written, and what I find most striking is that everything he argues is based on just a few simple assumptions about the world. So, my first goal today is to get him to lay out those assumptions. Maybe I can offer a few challenges to those assumptions, although I doubt he’ll find my arguments very persuasive. And then have him talk through how he gets from these simple premises to often counterintuitive, strikingly original conclusions.

LEVITT: s always interesting for me to meet people for the first time when I’ve been hearing about them and reading their work for 20 something years, because how they talk and how they write is not always so similar. In 2009, you laid out the three moral premises that underlie your thinking and they were remarkably simple I’d love to get you to explain each of them and to hear whether your thinking has changed at all. Are you up for that endeavor?

SINGER: Absolutely.

LEVITT: So, the first one is: “Pain is bad and similar amounts of pain are equally bad, no matter whose pain it might be.”

SINGER: Right. I certainly continue to hold that view. I think it’s pretty hard to deny that pain is intrinsically bad. Of course, that is compatible with the idea that sometimes we might think that pain is a good thing, that it helps to warn us of some danger, of the fact that we’ve put our hand in a flame. We might deliberately go and get some pain if we go to the dentist and we know that injection will be a little bit painful, but it’s better than the pain of a severe toothache. So, there are various circumstances in which we will accept pain, but intrinsically, if it wasn’t for the other good consequences, we would rather not have it.

LEVITT: Yeah, the pain is bad. Few people would argue with that. I think the more controversial part would be the contention that similar amounts of pain are equally bad, no matter whose pain it might be. Let me give you an example. So, in my own moral code, I tend to be very sympathetic to innocence. And I weigh pain suffered by innocence more than pain suffered by bullies. I put more weight on the pain of Ukrainian citizens than I do on the pain of Putin or Ceausescu or other tyrants.

SINGER: Yes, I think I would say that, you know, if Putin suffers pain as a result of what he has inflicted on the people of Ukraine, it would be hard not to feel some pleasure at that, or some sense that this is a good thing. That’s a retributive instinct that I think we have. And it is understandable because in a social setting, if people get away with hurting others, they’re more likely to do it again. And so, we think it’s good if they suffer from it, because then they’re less likely to do it again, or others will see what happened to them and they won’t be tempted to do the same. But if we were to isolate the pain that people feel from any other consequences, we should still feel that it’s a bad thing that anyone suffers, even if they’re somebody who has caused others to suffer much more. That’s perhaps hard for people to try to perform that thought experiment, and to think about, well, suppose that somebody was the last person on Earth, and there would be no consequences of any sort, whether they suffered pain or not. And suppose that they had done really bad things during their lifetime. Would it still be better that they would suffer for their last hours, that they would feel agony for their last hours? Some people might say that, “Yes, it would be.” But I think if we think about that, we’d say, “No.” The reason that we’re pleased when bad people suffer pain, is that it’s going to be a deterrent to them or others, and put that aside, and it’s still a bad thing that they’re suffering pain.

LEVITT: O.K. So, what about again, in my own world code, I put more weight on pain that’s around me, that’s happening right now in my own family, in my own neighborhood to myself than I do to pain that’s inflicted on strangers, that’s far away, that’s in the past or the future. Are you suggesting that I’m making a mistake in all of these regards?

SINGER: I’m suggesting that you’re making a mistake, if you really mean this as a moral evaluation. If you are reporting your psychological states when you see this pain, then I think that’s very natural. And again, it’s very understandable because we are more able to have an impact on the pain of those close to us. And also, we are evolved to have close ties, particularly with our kin, and with whom we’re in relationships, which can often be mutually beneficial. So, we have developed a sense of empathy with those close to us that just isn’t there when you’re talking about strangers far away. But if you really stop and think, you know, they’re people just like you and I, and why should we think that their pain doesn’t matter? So, this is the difference between taking an ethical point of view on it, and simply following on with the feelings that you may naturally have. 

LEVITT: So, yeah, it’s interesting because if I were given the opportunity to transfer pain from my children to a child in Bangladesh, maybe I’m a horrible person, but I think I would do that — I honestly think I would. Which is just saying I don’t adhere to it, even though I suppose if we took a vote among people who the better person is, you would probably win that vote. Just realistically, reporting my own view of the world, I think I carry a different one.

SINGER: But to say what you would do is a different thing from saying what, when you think about it, you think you ought to do — unless you’re a saint. I think there’s very few people where everything that you ought to do is what you do. And I’m not claiming that for myself either. What I would be interested to ask you is, suppose that when you transfer that pain that it would increase slightly so that the child of the stranger in Bangladesh would feel more pain than your child — nevertheless, let’s say you love your child, and so you press the button that transfers the pain and accordingly, the child in Bangladesh now feels more pain than your child would’ve, but your child doesn’t feel pain — how good do you feel about that? Do you think, oh, that’s fine? I’m really content in every respect, not just that I don’t have to see my child suffer now, but I really think that’s fine — I’ve done the right thing. Or would you feel maybe that wasn’t the right thing to do?

LEVITT: Yeah, that’s a good question. It really crashes headlong into this view in economics, which I have been so indoctrinated into with so many years in the field. In Adam Smith’s book The Wealth of Nations, he laid out what’s called the “invisible hand” theory, which is the idea that in a market setting, if every individual pursues their own self-interest, the market equilibrium is one that has many amazing characteristics. The right people are making the goods in the cheapest possible way, and the right people are purchasing those goods. And, obviously, this is a case where there’s an externality being imposed on someone else. But I think it’s not obvious. I guess you’re saying that the world would be a better place if everyone operated under the premise that they shouldn’t export pain from people close to them, to people far away. But still in the back of my mind, there’s this thought of some kind of Adam Smith idea that maybe it’s not the worst for everyone to pursue their own best interests and things might work out in the end although, obviously, I certainly haven’t worked out the math of it and you’ve thought a lot harder than me.

SINGER: You’re referring to the Adam Smith of The Wealth of Nations, but there’s also the Adam Smith of The Theory of Moral Sentiments. And I think that the distinction between the two is that in The Theory of Moral Sentiments, Smith is laying out a moral theory, perhaps in a sense, relatively ideal moral theory. And in The Wealth of Nations, he’s talking about the way we are, right? He’s not endorsing it. He’s just saying the way we are, things will be better off if we have an economic system where people are rewarded for pursuing their own interests. You know, the butcher has an interest in bringing you your meal, and then you’re likely to get the food produced efficiently. I think Smith is talking about different things there, and I think he’s not talking really ethics. In fact, there’s some remarks there where he acknowledges that’s not necessarily the ideal ethical view, but that’s just the way human nature is, and that’s how we’re going to produce the best economic system. I’m not necessarily disagreeing with that. I’m just saying, that’s not asking the same questions that I’m asking what is the right thing to do?

LEVITT: The second pillar of your moral philosophy is that the seriousness of taking a life depends not on the race, sex, or species of the being being killed, but on its own individual characteristics, such as its own desire about continuing to live or the kind of life it is capable of living. Riff on that a bit.

SINGER: Right. So, I think most people would accept this when it comes to race and sex that we don’t want to say that someone’s life is more valuable just because they’re a member of our race or because in the case of you and me, because they’re males, as we are. But having pushed that boundary out to include all human beings, which is a good thing, we tend to think that’s as far as it should go, because the differences between humans and other species are larger than the differences between different races or sexes. And that’s true. But what I say there is that it’s the individual characteristics, not the species that makes the difference. So, I’m not denying that there are differences between typical humans beyond infancy and typical members of other species. For example, we can have this conversation and there’s no member of any other species, as far as we know, that could carry on a conversation about abstract ideas as we are doing now. But what I say is that it’s the individual characteristics that make a difference. Suppose you have a human being with such severe brain damage that in terms of their abilities to think about their life, to reflect on the future, to be aware of themselves as a being who has existed in the past and will exist in the future, they’re actually inferior to, let’s say a chimpanzee or maybe even a dog or a pig. Now, is the life of that human being more precious merely because they’re a member of the species Homo sapiens? That’s what I’m denying. I’m acknowledging that the concerns of the parents might have some weight. But take a case actually that happened in Florida couple of decades ago where a woman gave birth to an anencephalic infant — that is an infant with only a brain stem, all other parts of the brain were lacking. So, anencephalic infants are not going to be conscious beings. They’re alive, because they have brain stem. They’re not brain dead. But they’re not ever going to smile when their mother walks in the room or anything like that. And because of this tragic birth, she wanted the organs to be donated to another child who could benefit from them. Maybe an infant with a fatal heart defect, who would’ve otherwise died. But the doctor said, “No, I can’t remove the heart from this infant because it’s a living human being.” And the mother went to court and the judge said the same. Said, “No matter how short or unsatisfactory the life of your child may be, it’s a human being and I can’t allow a doctor to cut out its heart.” So, the baby died, and the organs were wasted. That’s the kind of case where I would say, “Look, yes, this is a member of the species Homo sapiens. But if you are prepared to kill a pig or a baboon, or maybe even a chimpanzee in order to give that animal’s heart to a human who will otherwise die, you should also be prepared to remove the heart of an anencephalic human.” It doesn’t make any difference that they’re a member of the species Homo sapiens.

LEVITT: I want to come back to that, but I also want to get your third point out on the table first, which is, “We should consider ourselves responsible both for what we do and for what we refrain from doing.”

SINGER: Yes, I certainly still hold that. And my illustration of this comes from an early article that I published in 1972 called “Famine, Affluence, and Morality”, in which I asked my readers to imagine that they were walking past a shallow pond. And they noticed that there’s a small child who’s fallen in the pond. They could jump into the pond and rescue the child. There’s no danger to them because it’s shallow for an adult, but for this small child, it’s too deep and the child is going to drown. Suppose that you were wearing expensive clothes that day. And so, you thought, I’m not going to jump the pond because I don’t want to ruin my clothes. And after all, I’m not responsible for that child. It’s not my child. Nobody asked me to look after the child. So, I’m just going to walk on by the pond. Now, almost everybody that you put that example to will say, “That would be an awful thing to do. You’d have to be a monster.” You’re agreeing with me on that one, are you?

LEVITT: Yeah, I do agree with you on that.

SINGER: Yeah, good. So, you know, you have to be a monster to put the cost of your clothes ahead of the life of a child. But if you agree with that, then you are saying that we’re responsible for what we fail to do. That you’ve failed to rescue the child, and you’re responsible for the fact that the child drowns when you could easily have rescued the child. And of course, as the title of the article suggests, I use that to make the argument that if we don’t help people in extreme poverty who are dying from poverty related causes when we could relatively easily and relatively cheaply save their lives, we also have responsibility for that.

LEVITT: So, again, relating my own moral failings, I can see this number three really gets me in trouble because I spent a lot of time and effort trying not to do too many bad things. But there are so many things that I could do that I don’t do. And I feel almost no guilt about any of those. I live in deep denial of point number three, although acknowledging intellectually that I do agree with it, although I live a morally inconsistent life with it.

SINGER: Well, I’m glad that you agree with it intellectually anyway. And I’m not asking for, a hundred percent consistency here, because again, I don’t claim that for myself. But I do think once you recognize this, it should lead you to think about doing something for organizations that are effectively helping people in extreme poverty. And so, I founded this organization called The Life You Can Save, which recommends some of the most effective, independently assessed organizations that do this. And I hope that perhaps after our conversation, you’ll go and have a look and you’ll think, look, I could get a little bit closer to my intellectual agreement, and have my values a bit more in harmony with my actions by doing something for some of these organizations.

We’ll be right back with more of my conversation with Peter Singer.

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Now is normally the time when Morgan would come on and we’d discuss a listener question. But today we’re experimenting — we’re trying something new. We’ve moved that segment to the end of the show. So, instead, let’s go back to my conversation with Peter Singer.

LEVITT: I’d love to talk about some of the positions that those three moral pillars lead you to. And right now in the United States, abortion is certainly an issue that’s top of mind, where do you land on the abortion issue?

SINGER: Well, there’s a couple of things that I like to say about that. Firstly, I think that the wrongness of killing a being depends on the characteristics that the being has, not on the species. So, the fact that the embryo or fetus from conception is a member of the species Homo sapiens — and that seems completely undeniable. And that’s a point that opponents of abortion emphasize, they say you’re killing an innocent living human being, I think that if by human being, you mean member of the species Homo sapiens, that’s obviously true. You are. But the mistake that opponents of abortion make is to assume that ends the discussion of whether the killing is wrong. And I don’t believe it does. I think the fact that you’re killing an innocent living human being, who has no awareness whatsoever that they are alive, no capacity to have formed desires of the future, or to think about the past. And not even — if we’re talking about abortions up to about 24 weeks — not even a capacity to feel pain. Those are very relevant to whether it’s wrong to end the life of such a being. And I think for that reason, it’s not wrong to end the life of an embryo or fetus, certainly before there’s a capacity to feel pain. So, I don’t think that abortion raises a huge moral issue. I think the fact that a woman does not want to continue to be pregnant, does not want to bear this child, that’s sufficient to say that she is entirely justified to end that pregnancy. She may choose to have another pregnancy later at a more convenient time. That’s her choice. And that’s why I think that, in law, every woman should be able to have an abortion, at least up to the point where the fetus is capable of feeling pain. And even after that point, if the reason is a serious one, and if the method by which the abortion is carried out is one that would not cause the fetus to suffer significantly.

LEVITT: So, I’m trying to read between the lines of that answer, and almost everyone who argues around the issue of abortion argues from a liberty perspective. It’s either a woman’s right to choose, based on some view of her control over her own body, or it’s the unrepresented rights of the fetus, who isn’t able yet to choose. But it sounds to me like you’re making a whole different kind of argument — a utilitarian or consequentialist argument about abortion. Is that right?

SINGER: I am arguing it in a different way. Some people who are opposed to abortion think that the embryo or fetus has a right to life. And I don’t think that’s true for the reasons that I’ve just given, just being a member of the species Homo sapiens is not enough to give you a right to life. And then people on the other side sometimes say, “Look, the woman has an absolute right to control her own body. So, we don’t even need to discuss the question of the moral status of the fetus, because the woman has that right. I think you can’t really get around the claim of, does the fetus have the same right to life as any other human being? But on the other hand, when you confront that question, I think the answer is the fetus does not have the same right to life as any other human being. And it’s not a question of the woman’s right to control her own body overriding the right to life of someone else. It’s a question of the woman’s interests in not having a child overriding the lack of interest that the fetus has since the fetus is not the kind of being who has a right to life or because the fetus’ desires to continue to live are thwarted. Nothing like that is the case with abortion. So, that’s why I think it’s relatively easy for the woman’s desire not to carry that pregnancy to override any claim that the fetus has to continue to live.

LEVITT: So, one of your most controversial opinions, which I think follows fairly directly from the logic you just used to justify abortion, is that parents should be able to choose whether their profoundly disabled newborns should live or die. You alluded to that before, but am I right to think that that view, which is I think far more controversial than your view of abortion, that they’re actually really closely tied together?

SINGER: You’re correct, my views about the possibility of parents choosing to end the life of a severely disabled newborn does tie in closely with my views about abortion. And it ties in closely with something that I have to agree with about those who are opposed to abortion. And that is that neither the viability of the fetus, nor even the birth of the fetus, makes a sharp line where you could say, “Well, there’s no right to life before that, but there is a right to life immediately after that.” Because the characteristics that I’ve referred to — that is, the self-awareness of the fetus, the capacity to feel pain — those things, either they don’t exist immediately at birth. So, I don’t think a newborn infant is a self-aware being. And then at the same time, the capacity to feel pain, actually, I think does develop before birth, although quite late in the pregnancy, not as early as some opponents of abortion have claimed. Birth isn’t going to mark this sharp moral distinction between a being who has no right to life and a being who has a full right to life. Rather there’s a more gradual process of development as opponents of abortion have correctly said. So, that’s why I think that if you have a newborn infant who has severe problems, the parents should be able to decide whether their child will continue to live and whether that will be a good thing for the child, whether it’ll be a good thing for them and their family. In fact, it’s not as radical as you might think at first glance. For two reasons. One is those who are not completely opposed to abortion in almost all circumstances will accept that it’s O.K. for a pregnant woman to get prenatal diagnosis. And if the prenatal diagnosis shows that her child has a major disability, it’s all right for her to terminate the pregnancy. For example, earlier I discussed a case of an anencephalic infant, an infant with only a brain stem and no capacity for consciousness. There are very few such infants born nowadays because they are detected during pregnancy and invariably terminated. And I think studies show that something like 80 percent of women who are told that their unborn child will have Down Syndrome will terminate the pregnancy. And that’s by no means one of the more severe disabilities that I’m thinking of. The second is that if a baby is born with severe disabilities, let’s say, very premature baby is born with a massive brain hemorrhage or bleeding in the brain, which sometimes goes along with extreme prematurity. And the doctors perform a scan showing that the brain is very badly damaged and the prognosis for the child is pretty grim. They will ask the parents whether they would like to withdraw life support, knowing that if you withdraw the respirator, it’s almost certain that the child will die. And that will happen in every major neonatal intensive care unit around the United States or any other developed country that has such units. So, if that’s O.K., then let’s go back to that premise that I talked about before that you’re responsible for what you don’t do as well as for what you do, if you’re making a deliberate choice and are aware of the consequences. So, I think the doctors and the parents who make that choice are responsible for the death of their infant. I think that’s, nevertheless, the right decision for them if that’s how they judge the outlook for the child and for themselves and the family caring for that severely disabled child. If you think that my views are wrong, because they’re hostile to people with disabilities, you should think that you should never withdraw a respirator from a child because of a prognosis that there’s going to be a very severe disability if the child survives. In a sense, what I’m saying is simply, “O.K., since we’re responsible for what we cause by withdrawing treatment and since sometimes withdrawing treatment isn’t an option, let’s say, because the baby can breathe. We should be able to make the same choice by giving the child a lethal injection just as we now can make it by withdrawing the respirator from the child.”

LEVITT: Certainly everyone has not seen eye to eye with you on that. In your life of making often controversial statements, is that the one which has led to the greatest chaos, protests — things of that nature?

SINGER: Chaos is a little strong, but it has certainly led to the greatest number of protests, and the most opposition to my views. And, also to some significant misunderstandings of my views, which is why I just now went out of my way to indicate that, my views are not based on a hostility to people with disabilities. and that they certainly don’t show anything negative about people with disabilities in general.

LEVITT: So, when you came to Princeton, there were a lot of protests, a lot of attention. I think The New York Times said there was more commotion around your appointment to Princeton than any academic appointment since — was it Bertran Russell or someone from the 1940s?

SINGER: It was Bertran Russell. And when Bertran Russell was appointed to the City University of New York, people objected to his appointment because of what he’d written in an essay called “Marriage and Morals,” in which he suggested that you could have sex without being married. So, if I’m in the same situation as Bertran Russell, I hope that my views will be regarded as normal in another 40 years as his are now.

LEVITT: What was that like for you personally? Are you the kind of person who’s deeply affected by protest and threat or did you more or less go on doing your business?

SINGER: I would say that I more or less go on doing my business. Protest against my views started in 1989. So, I’d had a decade of some protests, not actually in the United States, but more in German-speaking countries where the Nazis’ so-called euthanasia program, I think made people particularly concerned to distance themselves from anything that looked like it might be something similar to what the Nazis were doing. Of course, what I was suggesting was completely different. It was offering parents opportunities rather than the state telling people that their children were not worthy of living because they were somehow a blot on the Aryan race. So, I’d had a decade to get used to protests, and by the time I came to Princeton I was able to go on with my business without being too disturbed by it.

LEVITT: I’ve only generated real controversy once and that was around my research with John Donahue about abortion and crime. But what was so stunning about the controversy to that argument early on was that both the right and the left were both furious with us. We had no one on our side. I almost watched with amusement because my life as an academic had been one in which no one ever paid attention to anything I did. And I actually was heartened by the fact that people were actually paying attention. My colleague, Gary Becker, at the time said to me that the one thing he absolutely hated was being ignored. And if people liked what he did or they hated it, he didn’t mind, but being ignored — he just couldn’t take that.

SINGER: Well, there’s some point to that. And in fact, the protest in Germany had exactly the effect of making my views better known in Germany. And I can trace that because my book Practical Ethics in which one chapter talks about these issues had been translated into German several years before the first protest in 1989. And it had hardly sold any copies. It sold copies in the low hundreds, I think, each year. And then in 1989, there were these protests. There was a lot of media publicity. It was in the magazine, the Spiegel, which was equivalent to say Time or Newsweek. It was in Die Zeit, which is one of the more intellectual Sunday newspapers. I was on various T.V. programs. And from that year on, Practical Ethics sold in the thousands. And was started to be widely taught in classrooms. In a totalitarian society, of course, this would not have happened. If somebody like Putin had been in charge and didn’t like my views, there’s no way that, the book would’ve sold at all after that. But at least in a free society, protests can be reported, and people can look at what’s being said and say, “Oh, this sounds interesting. Maybe it’s not quite as bad as the protestors thinking. I’ll have a look at it.”

LEVITT: You’ve been pushing for animal rights for 50 years fighting against what you call “speciesism”. Can you define that concept for the uninitiated?

SINGER: Speciesism is an attitude of bias or prejudice against a being on the grounds of that being’s species. Just as racism and sexism or attitudes of bias or prejudice against beings on the grounds of their race or sex. So, it’s intended to make that parallel. I didn’t make up the term, by the way, I took it from a man called Richard Ryder, who was opposing animal experiments. And I saw a leaflet which had the heading “Speciesism” on it, pointing out that experiments were being done on animals. There was a photo of a chimpanzee, who’d been deliberately infected with syphilis. You would never do such experiments on humans without their consent. Actually, we do know now that there were some experiments done on African Americans, of course, at Tuskegee, where the syphilis was not treated. But that was racism. So, again, makes the parallel that racism and speciesism can lead to somewhat similar consequences in some respects for and, of course, very different beings. So, this attitude of bias or prejudice, I think, leads us to not take seriously the interests of non-human animals when it’s convenient for us not to do. And one of the ways in which we don’t do that is by using them in research that is not lifesaving for humans, but has a whole variety of other purposes. Might be to test food colorings or cosmetic products that we don’t really need. And yet, we cause large numbers of animals to suffer and die slowly from poisoning in order to test those substances.

LEVITT: There’s a whole class of researchers who need to get tenure and animal research is a path to those folks getting tenure. I’m not defending that. I’m using that as a perfect example of the kind of research that happens, not because it’s truly important, but just because academics have to be busy.

SINGER: Absolutely, and they’ve been trained to work in a certain way, and they don’t know anything else except by experimenting on animals. And this goes on despite the fact that leading scientists — I think a former director of the National Institute of Health — said at one point, “We’ve become very good at curing cancer in mice. But it doesn’t translate to curing cancer in humans and we really need to change the way we’re going about finding cures.” And that’s one area, but the much, much larger area, of course, is the use of animals for food. And particularly in modern intensive farming, which, violates all of the needs that animals have, except the need to survive and grow and put on weight or lay eggs, whatever it might be. And gives them a miserable life in order to make the price of these foods a little cheaper. We’re talking about tens of billions of animals every year. In fact, more than a hundred billion, if we’re including fish farming. This is an enormous problem. We’re starting to realize that it’s not good for the planet or the climate or our health either, but it’s one that continues. And it’s one of the major things that I’m concerned about is trying to turn that around, if it’s possible.

LEVITT: Now, I would say that this belief in the preeminence of humans, our specialness, this categorical divide between us and all the creatures. It’s one of the most deeply held beliefs in Western society. Do you think that’s because it was so central to the Judeo-Christian tradition of God making man in his image?

SINGER: It’s interesting because certainly if you look at that Judeo-Christian tradition and you compare it with say, Buddhism or Hinduism, it seems like the separation between us and animals is sharper in the Judeo-Christian tradition, and less so in those Eastern traditions. And in fact, it’s true that in India, you find a lot more vegetarians. But it’s curious that when you’re traveling in Buddhist countries, most people are not vegetarian. Even some of the Buddhist monks or priests themselves are not vegetarian. And I think it’s not just the influence of religious traditions. I think it’s a kind of self-interest or a failure to really take seriously the idea of compassion for all sentient beings that is regarded as one of the first principles of Buddhism. So, it’s more complicated than just saying, “We have this speciesist Western tradition.” It’s something to do with the fact that maybe humans evolved with a taste for meat, because that’s a very concentrated food source. And in the time when we needed to use all the food sources we could in order to survive, developing a taste for that helped our ancestors to get enough to eat and survive.

LEVITT: That I am certain of. Nonetheless, it seems to me that pre-Darwin, before the theory of evolution, the elevated beliefs about humans make a lot of sense to me, but I’m really surprised these views haven’t fallen away in the ensuing 150 years. It seems a series of pretty easy steps to go from the theory of evolution to accepting that human preeminence is both temporary and the product of chance, not divine design. And from there incorporating animal welfare into our moral codes into fundamental ways. It all seems so scientifically logical to me. Are you surprised like me that somehow science hasn’t pushed in this direction?

SINGER: So, some scientists do push in this direction. I’ve had conversations with Richard Dawkins, for example, who’s a scientist who understands evolution very well. And he agrees that there isn’t this sharp gulf between humans and animals, and that should be reflected in our views about animal welfare. I think, finally, he became a vegetarian as a result of initially a conversation that we had. But you’re right. It’s surprising that we still think there’s this vast gulf, this discontinuity between humans and animals. Although, Darwin showed indisputably that we are animals. And really, when we have these conversations, we shouldn’t say humans and animals. We should say human-animals and non-human animals. It’s a little bit more of a mouthful, but that would be more accurate.

LEVITT: So, I recognize that I live my own life in a way that’s completely inconsistent, morally, because I do believe deeply like you, that animals matter, but I also do eat meat, although less and less over time. But I have to say somehow, because animal suffering is so effectively decoupled from my own experiences sitting at the dinner table, the factory farms and the slaughterhouses feel so distant, that the discomfort caused by my moral inconsistency — it’s more like background noise as opposed to a really intense pain. It’s interesting that I’m even aware of my inconsistency, and yet I still live with it.

SINGER: O.K. You do have some consistency problems as we were earlier. And especially as an economist, you’re aware of the fact that markets play a role in determining what is produced. So, as long as there’s a market for factory farmed animal products, it’s very likely that there will be factory farms. At least it will take a huge effort from democratic political systems to stop or control those factory farms. It’s relevant that you’re part of that demand that is creating the supply.

LEVITT: No, of course. Yeah. I fully recognize that. So, look, I’m fully aware that I’m complicit in this and I think I’m on a slow march to being vegetarian as the reality of that sinks in more deeply. My general impression is that there are a growing number of people like me, who are in larger, small ways altering their diets to reduce or eliminate meat. And I was recently rereading the latest edition of your book Animal Liberation, which was from 2015. And in the preface, you note the fact that meat consumption in the U.S., which had been rising for decades, suddenly fell every year from 2008 to 2015. So, in anticipation of our conversation today, I gathered the most recent data on meat consumption in the U.S. expecting that we’d be able to celebrate together the continuation of this downward trend. And I was honestly shocked to discover that U.S. per capita meat consumption has been trending sharply back upwards since 2015 and is now as high as it’s ever been — 265 pounds of meat per person, per year, in the United States. This must be so discouraging to you, having worked so hard for so long to try to bring light to this topic.

SINGER: It is discouraging and you’re right, that preface was written at a time when there was a dip, but the dip proved a temporary one. I’m not sure what the reasons for that are, but it’s certainly disappointing. And from a global point of view, the bigger problem is the sharp rise in meat consumption in China. And other parts of Asia as well, but particularly China, cause it’s such a large population. There are now significantly more animals in factory farms than there were when Animal Liberation was first published in 1975. And despite the fact that there’s been some progress in some countries and certainly much greater awareness of the issues of factory farming and of speciesism, the suffering we inflict on animals, from the point of view of how much suffering humans do inflict on animals, the world is a lot worse than it was in 1975.

You’re listening to People I (Mostly) Admire with Steve Levitt and his conversation with philosopher Peter Singer. After this short break, they’ll return to talk more about animal rights.

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If you happened to listen to my conversation with Will McAskill a few months back, he described a fascinating conundrum that’s arisen in modern philosophy called the repugnant conclusion. Now, the most obvious possible real-world application of the repugnant conclusion that I can see is to factory farming. I’m really curious to get Peter Singer’s take on this.

LEVITT: So, I recently had William McAskill on the show, who you know. And one of the things we talked about was the paradox of what philosophers call the repugnant conclusion. And I won’t do justice to Derek Parfit, the man who came up with it, in my restating of it. But the basic idea is that starting from extremely innocuous assumptions, one has led to the repugnant conclusion that a world with very many individuals living pretty terrible lives — lives barely better than never having been born — seems to be better than a world with a much smaller number of individuals living fantastic lives. And as Will McAskill described this repugnant paradox to me, my mind immediately went to the animals we eat — cows, pigs, chickens, because there are huge numbers of them, and they have miserable lives. So, I have two questions for you: Do we know enough to make informed judgments on the question of whether the awful lives of factory farmed animals are worse than not living at all from the perspective of the animal?

SINGER: That’s a very good question. That is my view, that typically factory farmed animals have lives that are worse than not living at all. Of course, it varies with each species. Perhaps that’s not true of, let’s say, cows raised for beef, who are relatively freer. They’re free for the first part of their lives, generally. They’re with their mothers on grass and then they’re brought into a feedlot. And I think the feedlot conditions are much worse for them. But you could argue that their lives are better than nothing. But if you take factory farm chickens, each individual chicken is almost worthless. And they’ve been bred to grow so fast that their immature leg bones don’t support the weight of their bodies properly. Chickens raised for meat are killed between six and seven weeks. So, they’re very young birds, but their body size is that which used to be only possible with a bird that was at least twice as old. So, experts now believe that they’re in pain for the last couple of weeks of their lives. It’s been compared with somebody with arthritis being forced to stand up all day. And if you ask “Why don’t they just sit down?” The answer is because they’re on litter that is full of their droppings. And, because of the ammonia in their litter and moisture in the air, if they sit down for long periods of time, they actually get alkaline burns on their legs and thighs. So, they can’t really sit comfortably. And sometimes their legs just collapse under them. And if they’re not within reach of food or water, they’re just going to starve to death or die of dehydration because there’s nobody looking after the wellbeing of individual birds. Nobody would ever think of getting treatment for them. And probably not even walking through the shed and picking them up and wringing their neck. So, with chickens, by far the species that there’s most of, I think their lives are negative and miserable. And that’s probably true of fish farming as well, which is, you know, very intensive and confining and huge numbers, again. So, I would say for the majority of animals who are factory farmed, their lives are negative. But I couldn’t say that with confidence for all of the species.

LEVITT: So, let’s just say, hypothetically, that we could improve the lives of factory farmed animals enough that they would view their lives as better than not being born. Would the repugnant conclusion lessen your ethical concerns about animal welfare at all?

SINGER: So, the question is whether we ought to accept the repugnant conclusion either about animals or about humans. The very fact that Parfit gave it that name suggested that he was reluctant to do so. And throughout his life, after having put forward that conclusion and incidentally, when I went to Oxford and attended classes as a graduate student, I attended a seminar that Parfit gave, and that was when I first heard of the repugnant conclusion. And that was in 1970. So, Parfit did continue to think about it for the next 45 years or more. And he continued to try to find what he called “theory X”, which would be the theory that somehow explained why the repugnant conclusion was not something that we needed to accept and why there was an alternative plausible view, but he never found it. So, the first question is, do we think that it’s O.K. for beings to have barely positive lives? And that it’s actually a good thing if more of them exist, even though their lives are just barely on the positive side? Uh, I’m not sure about that. I can’t claim to have done any better than Parfit in trying to find a plausible explanation of how we should think about increasing populations. But if you do accept the total view and, it be a good thing if there were these vast numbers of animals living barely positive lives? I suppose you might think that, but the other thing I would say is, to make the judgment about whether the lives of these animals are positive, you would need to know more than we do about their mental states during the normal periods when they’re just existing in the factory farm and eating, occasionally, and what kind of stresses they’re under from the crowding. And you would also need to think how you weigh particular moments of great suffering. So, let’s say, when they’re taken out of the factory farm and packed into the trucks and then taken to slaughter, and how you think about the fact that a percentage of the chickens are not humanely killed, but go into what’s called a scalding tank, a tank of boiling water that is intended to make it easier to get rid of the feathers. But, some of them go into it fully conscious. They haven’t been properly stunned or killed beforehand. So, how do you weigh up those moments of extreme suffering as compared to the other moments of, yes, possibly just barely positive existence?

LEVITT: So, morals and ethics clearly play a large role in how you lead your personal life. I’m curious whether you were a moral person before you studied philosophy or did studying philosophy bring morality to the fore in your own life?

SINGER: Well, I don’t think I was a particularly moral person before I studied philosophy. And even when I began studying philosophy, I don’t think it had an immediate change. The real factor that made me bring ethics into my life was when I had a chance lunch with a fellow student in Oxford, a Canadian called Richard Keshen. And at that lunch, he asked whether there was meat in the main course that was being served. And when he was told there was meat in it, he took a salad plate, which was the only other option to the hot meal at that time. And so, I asked him what his problem was with meat. And he just said he didn’t think it was right to treat animals the way they get treated to be turned into meat. And that’s when I first learned about factory farming, which I knew nothing about. I think very few people knew anything about it in 1970. And when you think about the ethics of what you’re eating, it’s something that brings ethics into your life in a daily way. I was an Australian, we ate lots of meat. Meat was cheap. In fact, when I went to Oxford, one of the things people said was, “Oh, you’ll find the meat in England is awful and expensive.” I guess I solved that problem after becoming a vegetarian. But that’s what made me think then about that issue or the treatment of animals, and also then more or less, I guess, I had been previously thinking that, you know, here was I a relatively privileged, comfortably off citizen of an affluent country. And there were these people who were in terrible need because of extreme poverty in low-income countries. And shouldn’t I be doing something about that? I’d thought about it, but perhaps more in the way that you were saying earlier that I hadn’t consistently acted on that thought. But once I’d made the decision that I couldn’t go on eating meat, I thought, I should also be giving away some of what I’ve got that’s spare to help people. And so, it was really those circumstances, when I was a graduate student studying philosophy that made me really think harder about living in a more ethical way.

LEVITT: You pondered being a lawyer early in life. Your father was a coffee importer, so you could have gone into business. Can you imagine those lives? It seems like you really found what you were designed to do. Is that your feeling as well?

SINGER: Yes, I think that’s right. Look, I think I enjoy arguing and so I could have been a lawyer and perhaps I could have been quite a good lawyer because lawyers need to be good at arguing. But I think I found a field in which I can argue much more broadly about a wide range of topics. And I do think that I’ve had an impact on people. I know many people who’ve written to me saying that it’s changed their lives and it’s changed their lives in ways that are positive, both for them and for others.

LEVITT: You probably don’t remember, but one of my students, her name is Maddie Toma. She said she was going to visit Princeton for a day and that there’s no one who had ever influenced her more than Peter Singer and did I think he would ever talk to her if he got a cold call from an undergrad who was visiting campus for a day? And I said, “No, I’m sure he won’t talk to you, but it can’t hurt — possibly he might.” And she spent a long time with you and reports back to me that there’s not a single thing in her life that isn’t driven by what she’s learned from you on every dimension. You probably have no recollection of this conversation and the impact it had on her, do you?

SINGER: I have to confess, you’re right. I don’t recall the conversation, but I’m glad I spoke to her. And I know you’ve got a lot of listeners, so please don’t assume if you’re listening that I’ll have time to talk to you, but I try to, and, you’ve explained the reason why. That it has an impact on people and through that, a larger impact on the world. I’m really glad when this happens.

LEVITT: Whenever someone starts this story, like I just started this one, which is, “Six years ago I wrote you an email,” I hold my breath in dread because I presume the answer’s going to be, “and I was so disappointed that you never wrote back.” Which is usually what I don’t do is write back. And it is always such a good feeling when they say, “and you wrote me back,” and, you know, they don’t usually say to me that I changed their life, but they say, “You wrote me back and that was very kind.” I did want to report that back because I do believe that good deeds should be rewarded. And I think it’s just another indication of how you’re more successful at living your life according to the moral codes that you’ve laid out than most others, including myself.

SINGER: Well, that gives you all something to aim for. But, as I said, I’m not claiming to be a saint at all. I think there are many things that I could do better as well.

Peter Singer may not be a saint, but I hugely admire the way he’s staked out a set of beliefs and so effectively and persuasively explained the implications of those beliefs for how we should live. Oftentimes the people we admire most are the ones who are most different from us. And as became quite apparent in our conversation, unlike Peter, I definitely have not figured out how to live a life where my actions follow in a sensible way from my beliefs. But I do think I understand myself a little bit better after our conversation than I did before, and that’s at least a step in the right direction. And now our listener question segment.

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LEVEY: Hey Steve. So, our listener, Christine wrote in, she recently moved her freshman daughter to college, and she was struck by all the new construction on campuses like state-of-the-art housing for students, new dining halls, new sports arenas. It felt to her like the exorbitant tuition bills are funding unrestrained spending. And she believes that given the choice, students might opt for less debt than enjoy a nice gym for four years. So, as an economist and the professor at a school with tuition of over $60,000 per year, what do you have to say to Christine?

LEVITT: Well, she’s certainly right. If you go on campus, the buildings are beautiful, and they’re new, and there’s better stuff all the time. But I don’t actually think that’s why tuitions are so high, because almost all of those buildings are funded by gifts from donors. It just turns out that at universities, the easiest way to raise money is to attach that money to a building — to etch the donor’s name in stone, above the door of the building. Donors love that. So, while Christine is absolutely right that there are a lot of shiny buildings on campuses, I don’t actually think that’s the source of high tuition.

LEVEY: So, what is the source of high tuitions?

LEVITT: The source of high tuitions is that people like me are paid exorbitant salaries for doing almost nothing, right? And the fundamental problem that universities face is that their faculty are really high skilled. And the labor market is very tight right now for high-skilled workers. The professors at top universities have lots of job options. They could go work in the private sector, in finance, and so there’s an equilibrium that does lure people like me to stay academics, but it’s at a relatively high salary, and consequently, that just makes college tuitions expensive because there aren’t that many students per faculty member.

LEVEY: But that doesn’t explain why tuitions are increasing. Are salaries for professors increasing?

LEVITT: Yeah, so, great point Morgan. Now, I don’t know about generally, but I’ll tell you my own experience. When I was on the job market about 25 years ago, Harvard offered me $32,000 a year as an assistant professor. The current going salary can be up to $200,000 for the exact same assistant professor position today. Now part of that is accounted for inflation, but not nearly all of it. The wages of professors have gone up dramatically over time and that just mirrors the broader patterns we’ve seen in the economy, where highly educated people have seen their salaries go up sharply over the last 25 years, whereas people with less education have seen their salaries stagnate or even go down. So, really, it’s a microcosm of the economy as a whole. Because the people teaching at universities are themselves so highly educated, it’s an even more extreme version than we see elsewhere in the economy.

LEVEY: Okay, Steve, how about a salary cap for professors, like in sports leagues where there’s salary caps for baseball players or football players?

LEVITT: I think those salary caps only work in those sports leagues because there aren’t really any other options for a basketball player to get paid millions of dollars other than to be in the N.B.A. But for an economics professor, well, I could go work in the private sector; I could go be a consultant; I could go work in finance.

LEVEY: Right. You would just leave the field altogether.

LEVITT: Yeah. I think that our general experience with price caps, and salary caps are an example of that, is that in a market economy, they just don’t work well. They lead to shortages. So, in the end, what you’d have would be universities that were bereft of faculty where you just wouldn’t be able to attract the kind of people you would want to train the next generation of students.

LEVEY: Christine, thanks so much for writing in. If you have a question for us, our email address is That’s It’s an acronym for our show. Steve and I do read every email that’s sent and we look forward to reading yours.

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That’s it for today. We’ll be back in two weeks with a guest who I’ve wanted to host since the beginning of this podcast.

GOODALL: You know, there was all this, “Jane is just a Geographic cover girl. Jane is getting support from Geographic because she has nice legs,” which today would be such a sexist remark. But, you know, back then I thought, “Well, if my legs have got me on the Geographic cover, and that’s got me money to study chimpanzees, thank you, legs!”

That’s primatologist Jane Goodall. See you in two weeks.

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People I (Mostly) Admire is part of the Freakonomics Radio Network, which also includes Freakonomics Radio, No Stupid Questions, and Freakonomics M.D. All our shows are produced by Stitcher and Renbud Radio. Morgan Levey is our producer and Jasmin Klinger is our engineer. Our staff also includes Neal Carruth, Gabriel Roth, Greg Rippin, Rebecca Lee Douglas, Julie Kanfer, Zack Lapinski, Ryan Kelley, Katherine Moncure, Eleanor Osborne, Jeremy Johnston, Daria Klenert, Emma Tyrrell, Lyric Bowditch, Alina Kulman, and Stephen Dubner. Our theme music was composed by Luis Guerra. To listen ad-free, subscribe to Stitcher Premium. We can be reached at, that’s Thanks for listening.

LEVITT: Do you know who I am?

SINGER: Oh yeah, sure. Of course I know about Freakonomics. Doesn’t everybody?

LEVITT: O.K. Just wanted to make sure. Sometimes people you know, just end up talking to me and they don’t know who I am.

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  • Peter Singer, professor of bioethics at Princeton University.



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