The Secret of Humanity? It’s Common Knowledge.

It was over five years ago that we recorded the first episode of People I (Mostly) Admire. My very first guest, Harvard linguist, Steven Pinker. He’s kept busy since then, writing two books and emerging as one of the leading advocates for academic freedom.

PINKER: When it comes to sociology and psychology, I think you just can’t do your job if you’re constantly watching your back. It perverts the whole enterprise. You just can’t do it honestly. 

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

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Five years ago, we talked a lot about his book entitled, Enlightenment Now: The Case for Reason, Science, Humanism, and Progress. I loved the book and I very much agreed with it, but I made fun of him because it seemed to me that everyone already believed in science and knowledge and progress. Did he really need to write a book about defending those principles? Well, I guess the events of the last five years have proven how naive I was and how much science and reason do need strong advocates. I started this conversation by asking him if he understood what had happened to create so much hostility to science.

PINKER: In a more recent book, Rationality, I tried to figure out what would seem to be obvious, namely that rationality is a good thing and science is a good thing. Why should those even be controversial? They were in part politicized because people thought that the institutions of science, even more so today are themselves political. There’s also a background romanticism of Does reason mean that you’ve got to be a grim, emotionless drone who can’t enjoy music and sunsets and playing with children? So I had to disabuse people of the idea that using reason means that there’s no such thing as human goals, preferences, emotions, and so on.

LEVITT: Yeah, in economics, rationality has really gotten a bad name. And my own reaction is that, of course, the kind of rationality we assume in economic models where people understand and process all information perfectly — I don’t think we adopt those assumptions in economics because we think that’s either the right way for people to act or a realistic one. It just helps with the math, right? That’s why this really strict adherence to rationality is so prevalent in economics over time.

PINKER: Yes, it is my understanding as well, and I often hear it said that economics assumes that people are selfish and rational. Where I take a lot of the modeling to be — what is the benchmark? What is the ideal? What would it be for an agent to be rational, largely in the sense of self-consistent. But it neither makes the empirical claim that human beings, in fact, are rational actors. Nor does it either say or assume that people have to be completely self-interested in the sense that they don’t care about anyone else. If you care about someone else, that goes into the utility function, that’s something that a rational person would want to consistently do. Now, I shouldn’t be saying this to you, you’re the economist, but this is at least my understanding.

LEVITT: There was a moment — so when I first got to the University of Chicago about 25 years ago, there was a kind of craziness that had taken hold where it became a game. And the game was, Give me any behavior I see in the world and let clever people try to reconcile that with rational behavior.

PINKER: I know what you mean.

LEVITT: It was just an aberration, I think. It was a case where economics had a lot of success and so it just became this intellectual activity and I found it really offputting and I’m glad to say it disappeared. Especially with behavioral economics coming along, it went very much out of fashion because the new game turned out to be not, How can we explain any behavior with rational action, but, What kind of quirks and foibles can we explain things away with? And, in fact, that game was almost as ridiculous because there were so many degrees of freedom in both of them that of course you could always come up with a story. There wasn’t a whole lot of attention paid to whether the story made any sense. There was actually the reasonable story to explain things.

PINKER: On the cognitive psychology side of the divide, I’m from the academic discipline that delights in showing that people are irrational, probably to an extreme — some of the fallacies that homosapiens get saddled with may not be fallacies in a realistic environment. But that was the backlash against the idea that if humans do it, there must be some rationality behind it.

LEVITT: So you got a new book out and it’s called When Everyone Knows That Everyone Knows, and it’s on the topic of what academics call common knowledge. And I have to say, my initial reaction upon hearing the topic of the book was to wonder how you could write a whole book about a topic that is so narrow and academic. And that reaction actually made reading the book especially enjoyable because you took an idea, common knowledge, that my whole adult life I have viewed as tiny and uninteresting. And you made a convincing case that it’s actually fundamental to the way we live our lives. It’s always fun for me to read books about topics that I don’t know much about, but it’s way more fun to read a book about a topic that I think I understand, only to realize that I had never actually seen the true implications of the idea. 

PINKER: So common knowledge in a technical sense, being the state where I know something and you know it, and I know that you know it and you know that I know it and I know that, you know that, I know that you know it, ad infinitum. Which seems impossible because the thinking of thoughts, to use a fancy word, recursive mentalizing; mentalizing means you try to get in someone else’s head. Recursive mentalizing is you try to get inside someone else’s head while he’s trying to get into your head or someone else’s. So you’re taking it up a level. So that’s the process that we’re talking about. I came to it from psychology in particular, psychology of language. In a book that I wrote 15 years ago, The Stuff of Thought: Language as a Window into Human Nature, I raised the puzzle of, Why people don’t just say what they mean? Why do we have politeness? Like, you know, if you could pass the salt, that would be awesome. Why do we have veiled bribes? Like, someone trying to jump the queue in a restaurant might hand the maître d’ a $50 bill and say, “I was wondering if you might have a cancellation,” instead of, “Would you accept $50 in exchange for seating me right away?” Or, sexual come-ons: Netflix and chill? You want to come up for a coffee? Veiled threats like in The Sopranos. I hear you’re on the jury of the Soprano trial. It’s an important civic responsibility. You got a wife and kids. We know you’ll do the right thing. Why don’t people just blurt things out? Why do they insist on making their hearer read between the lines, connect the dots, catch their drift? The answer I came up with at the time, at least, the main answer was that the difference between an innuendo that’s obvious enough, and blurting something out, is that when you blurt something out, it creates common knowledge. It isn’t just that your hearer knows what you meant, it’s they know that you know that they know what you meant. Common knowledge ratifies our social relationships. Are we platonic friends? Are we supervisor and supervisee? Are we neighbors? Are we lovers? These relationships depend on common knowledge. By avoiding common knowledge with an innuendo, you don’t blow up the relationship, but you still convey the message.

LEVITT: So your conclusion is going to be that common knowledge is fundamental to everything. It’s interesting to me that you came to it by observing behaviors that are trying to avoid establishing common knowledge. It’s very backdoor entry point. 

PINKER: It is a back door. And as I began to read more about it, I discovered that it plays a role in politics and economics. In economics, the idea of common knowledge plays a role in things like confidence in currency or the banking system. What makes paper currency valuable? Everyone else thinks it’s valuable and they think it’s valuable because they think that everyone else thinks it’s valuable. And conversely, you can get hyperinflation if people start to lose confidence in the currency. Or bank runs, people withdraw their money ’cause they think that other people are withdrawing their money. Not necessarily because either of them think the bank is unsound because they worry that still other people think that it’s unsound. And if everyone withdraws out of fear of everyone withdrawing at once, that can actually create the very panic that people start worrying about. Why does speculative investing as opposed to just investing for anticipated returns, like, you know, invest in a factory ’cause they have machinery that’ll build widgets. They’ll sell the widgets. You get a share of the profit. But a lot of investing is, you hope that it will be worth more in the future and you can sell it at a profit. Why do you hope that? Well, because you think other people might think that other people will hope that it’s worth more, and so they’ll buy it from you. And Keynes tried to explain it by reference to a beauty contest where the object of the contest is not to identify the prettiest face, but to identify the face that the most other people guess the most other people guess is the prettiest face. Each of them trying to think about what all the other contestants are doing, all of them thinking the same thing. And he’s suggested that buying a commodity or a stock or a currency in the hope that it’ll appreciate simply because other people will want to buy in is analogous to this beauty contest. And going back to the beginning of the conversation of phenomena that seem utterly irrational, might have hidden logic. And in the case of economics, again, I feel odd saying this to you, so you can tell me if I’m full of bologna or not, but phenomena like irrational exuberance, animal spirits, running for the exits, bubbles, busts, bank runs, speculative attacks, a lot of these kind of chaotic phenomena that you wouldn’t at first think obey laws of supply and demand, they may be the results of Keynesian beauty contests, which consist of people trying to out psych each other.

LEVITT: So, you just gave a whole string of excellent examples of what you’re talking about, but could I try to summarize your argument just in one sentence? Just to see if I’m getting it right. I think your claim is that if we as a species didn’t have the ability to do the mental processes involved in understanding common knowledge, the entire nature of collective life and human relationships would be impossible. Is that too grandiose summary of your main argument?

PINKER: No, that is exactly right. Cooperative phenomena: Many people or two people even do something ’cause it’s in both of their interests as long as they’re both doing it the same way. Like, driving on the right as opposed to driving on the left. There’s no logical reason you should drive on the right, but there is a good reason to drive on the same side that everyone else is driving on. Paper currency being another example. Recognizing the authority of political leaders, recognizing organizations and institutions — all of those succeed because these are things that exist because everyone acts as if they exist. But I have to add one more psychological observation because some of the listeners may be wondering, Well, you’re saying that all these social and political institutions, government, corporations and money and universities all depend on everyone thinking what everyone thinks that everyone thinks that everyone thinks. Your head starts to hurt after a couple of iterations. That can’t be right. So the extra piece is that there are some signals that generate common knowledge. They’re public. You see them when you know that everyone else is seeing them or you hear them when you know that everyone else is hearing them. And that can give you common knowledge at a stroke. You don’t have to actually think through the Russian doll of, I think that she thinks that I think, if it’s out there, if it’s salient, if it’s public, that’s enough. The bare intuition is just that it’s public or out there. Just to connect the two parts of our conversation, my initial interest coming from language and the phenomena of economics. It’s a kind of conventional wisdom in macroeconomics that often a financial leader, like the Chairman of the Fed can sometimes inadvertently move markets by blurting something out that then creates a cycle of self-fulfilling expectations. So that’s why people parse the nuances of what the Chairman of the Fed just said. Conversely, there’s a famous quote from Alan Greenspan when he was the Fed Chairman. “Since I’ve been a financial leader, I’ve learned to mumble with great incoherence. If I seem clear to you, you must have misunderstood what I said.” So this vagueness is actually a deliberate strategy knowing that they could set off cycles of he thinks that he thinks that he thinks and can generate a phenomenon that may not have existed if people didn’t start thinking that way.

LEVITT: Alright, so just to make sure everyone’s on the same page, I want to say something completely obvious and you say it in the book, but it’s easy to forget and that is that modern life is predicated to an astounding degree on our ability to coordinate. Once you actually start thinking about what you can do if you aren’t coordinating with your family, your spouse, your job, the bus lines, language — virtually everything we do depends on coordination. I don’t think many people would dispute that. But just to hammer home your main point, I think you’re claiming that in the absence of common knowledge, much of the coordination becomes extremely difficult. Why can’t we coordinate without common knowledge?

PINKER: Yeah, so I’ll go back to one of the original parables of common knowledge from the political scientist Thomas Schelling, 60 years ago. So he imagines a couple get separated in New York. They don’t have cell phones in 1960. How do they find each other? Now, he can’t think, Well, she likes to go to the bookstore, so I’ll meet her there, because she could be thinking, Well, he likes to go to the camera store so I’ll meet him there. And then she might think, Wait a second, he likes to go to the camera store. He knows that I like to go to the bookstore, so he’ll go to the bookstore where he’ll think I’ll be. But wait, he knows that I know that he likes the camera store, so he’s going to think I’m going to be considerate and go to the camera store so he’ll go to the camera store after all. It’s not enough for each one to know the other’s preference. Each one has to know the other one knows. And what Schelling suggested is in the absence of common knowledge, the next best thing is common salience. What he calls a focal point. In the case of our couple separated in New York, he speculated that they might gravitate to the clock in the middle of Grand Central Station at noon, even if it wasn’t particularly close to where they’d been separated, simply because it’s likely to pop into the mind of the other, and each one knows it’s going to pop into the mind of the first. And so that’s a way of kind of cutting the knot. In that case, common salience, which can then generate common knowledge. Being on the same page, not getting your wires crossed — all of these depend on people not only knowing what other people will do, but they can’t know what other people do in these cases unless the other people know what they’re going to do. I suggest that’s why our species evolved language. It’s a way to divide up the chores to coordinate on a hunt or split up babysitting; all the things that we do that depend on people acting together. But we also have public common knowledge generators like ceremonies where you inaugurate a president or you crown a king, or two people get married. Or you have laws that start at midnight on January 1st. Things that everyone can see, that everyone can see everyone seeing. And that’s what allows you to coordinate. 

We’ll be right back with more of my conversation with psychologist Steven Pinker after this short break.

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LEVITT: I started our conversation by saying that I had always thought of common knowledge as being silly and unimportant. And somebody listening might wonder, Wait, why would I think common knowledge is silly and unimportant? And Steve Pinker thinks that it’s the most important thing in the world. So, the place where I’ve experienced the concept of common knowledge is almost exclusively in the field of game theory, which is used by economists and biologists and political scientists to model strategic interactions. And so, what happens is an economist like me wants to model how two people will behave in a particular setting. The prisoner’s dilemma might be the best known example. Let me just describe how one goes about modeling a situation. Well, first I need to define the actions that the players have available to them, and then the timing of when the players will act. So maybe they act sequentially or maybe they act simultaneously. And then I need to assign the payoffs that each of the players get, depending on the actions that are taken. And, finally, I need to specify what each player’s beliefs are about the other player. And here’s the thing, if I don’t assume that the players have common knowledge about all the elements of the game, the timing, the payoffs, etc., then the math gets incredibly hard. And we already talked about that with rationality and economics, how economists assume rationality because otherwise it’s really hard to do the modeling. Well, in a game theory context, it’s common knowledge that makes the math easy. So essentially every paper I’ve ever read in game theory ends their theory section by assuming common knowledge. And not because it’s necessarily a realistic assumption or because, as you argue, it pervades every aspect of societal behavior, just because otherwise it’s hard to solve the equations. So, in my mind, I have just always attributed common knowledge to have no standing or importance other than to help people like me be able to write academic papers more easily.

PINKER: Interesting. You’re right that for most situations in game theory to come to some conclusion about what the actors should do, you have to assume both that they have common knowledge of the payoffs and common knowledge of each other’s rationality. Social life is game theory. We do coordinate, we do try to outsmart each other. Sometimes we just try to find out what page the other guy’s on, so we’ll be on the same page. And so the assumption of common knowledge, it’s a cognitive assumption, namely, it’s about knowledge. Knowledge about knowledge. And so it does actually have a counterpart in our mental life, our experience. It does have a role in actual economic phenomena — this is from an economist named Justin Wolfers. During the pandemic, you might remember there was a shortage of toilet paper. Wolfers claims that it wasn’t necessarily that the manufacturers couldn’t keep up with the demand. Instead, rumors started to spread, and they’ve been decades in the making, that whenever there’s a public emergency, toilet paper gets hoarded. I better go out and get some because the shelves will be stripped bare by people not even worrying that there’s an actual shortage, but worrying that other people might think there’s a shortage. And apparently, this is one theory, the idea might go back to a common knowledge generator from the 1970s, namely the Johnny Carson show, The Tonight Show. When you watch The Tonight Show, you knew that a lot of other Americans were watching it. And one night around the time of the gas shortage in the early ‘70s, he said, “You know, there are a lot of shortages these days,” and it’s true. There were shortages of meat and sugar and gasoline. And he said, “But you hear the latest? I read it in the papers. There’s a shortage of toilet paper.” Now, it turned out there actually wasn’t a shortage of toilet paper. Although, once he made that joke, then there became a shortage of toilet paper. And, according to one theory, since that time, it’s conventional wisdom that people hoard toilet paper, which causes people to hoard toilet paper. Which is why one way of alleviating the shortage of bringing this crisis to an end is that when C.V.S. and Duane Reade started to post signs saying, “Maximum three roll per customer,” it didn’t so much throttle the demand, but more important you knew that no one else was buying more than three rolls, and so you didn’t freak out if you could just buy one or two or three rolls.

LEVITT: So one could presumably test the Johnny Carson theory because people in Europe don’t watch Johnny Carson. When there are crises in Europe, do they also hoard toilet paper?

PINKER: Yes. That would be a way to test it, absolutely. And one thing that I talk about in the book is the Super Bowl being another common knowledge generator because in America, again, you can test this by comparing it with Europe, it’s such a national ritual to watch the Super Bowl that when you watch it, you know that other Americans are watching it and they know that other Americans are watching it. And according to an analysis by Michael Chwe, a political scientist, products or services that depend on network effects, that are only attractive if enough other people are using them, are often introduced on the Super Bowl because when people watch it, they know that others are watching it. Examples being, like, the Macintosh computer in 1984, and more recently trying to gin-up speculative investing in cryptocurrency. All the crypto exchanges had high concept ads a few years ago in the Super Bowl.

LEVITT: That’s really interesting. When I think about Super Bowl ads as an economist, I think at a very superficial level, which is there’s some cost of getting the ad and you reach this many people and an impression is worth this much and either it’s a good deal or a bad deal. This idea of network effects and common knowledge actually changes that calculus completely for certain kinds of goods. Really, interesting insight.

PINKER: Well, and Chwe tried to test this by seeing if the decision to advertise on the Super Bowl as opposed to elsewhere, the cost per viewer, per eyeball, according to this theory, it isn’t just the number of eyeballs, it’s that those eyeballs know that there are other eyeballs. And what Chwe claimed is that if you divide up products into those that do have network effects, so some obvious ones would be, like, a new credit card, where you’re not going to get a credit card if you don’t think merchants are going to accept it. And a merchant isn’t going to accept it unless he thinks a lot of customers are going to have it. So how do you break that knot? Well, the Discover card was introduced at the Super Bowl. Or, we mentioned the Macintosh computer, speculative investing. And Chwe also said there are certain brand-driven products; there’s some people, it’s really important to be seen as a Nike wearer as opposed to an Adidas wearer, and brand-awareness products would also, according to Chwe, depend on network effects. Getting to the punchline, what he tried to show is that advertisers on the Super Bowl — were willing to pay more per watcher for public network products like credit cards, jobs search sites, than for things consumed in private like batteries and motor oil and breakfast cereal. 

LEVITT: Do we know whether any animal species other than humans have an understanding of common knowledge?

PINKER: There’s a sense in which they do, but without the recursive mentalizing. That is, if common knowledge can be generated by a salient public signal, and if it is necessary for coordination, then that connection can sometimes be done without unpacking the, Oh, I know that he knows that I know that he knows. But a couple of examples that I mentioned are what’s called broadcast spawning. So this involves a creature that doesn’t even have a brain to think with. Namely, the lowly coral. So coral have the problem — they’re sessile, they’re stuck to the ocean bottom — how do they mate? They can’t get around. So they release sperm and eggs into the water, but they can’t release sperm and eggs 24/7. They’ve got to do some conservation. Ideally, they would release it at the same time that other coral did, so that the eggs and sperm have some chance of finding each other. And what a number of species do is they coordinate on the full moon, either the full moon itself or maybe five days after the full moon. All the coral can sense the full moon just with receptors for light, of course. And the fact that they can, and they assume that other coral can too — they lock onto that and they release their egg and sperm, based on this public salient signal of the full moon.

LEVITT: See, this actually seems like a counter example to your argument because I thought your argument was coordination absent common knowledge is really difficult. But I think what you’re describing is actually a coordination mechanism that doesn’t depend in any sense on common knowledge. It’s somehow evolved. I thought at the heart of your view of common knowledge, somebody had to have a theory of mind. You can rebut me, but first can you just explain theory of mind in that as well? 

PINKER: Yeah. So theory of mind is the term in psychology — it’s a little bit misleading ’cause it’s actually not a theory that the psychologist or the scientist has, but it’s the intuitive or folk theory that each one of us has about what’s going on in the heads of others. And it was introduced maybe 40 years ago. And questions like, When do children develop a theory of mind? Do chimpanzees have a theory of mind? It’s basically, do we think about others’ thoughts? So recursive mentalizing, as thinking about thoughts, takes it to the next level. It’s a theory of mind about the other guy’s theory of mind. You can skip that step, the coral do, and go from something that’s public to coordination where, I don’t think they literally know it, but there’s a metaphorical sense in which the species quote unquote knows it. Coordination doesn’t literally require the intermediate step of knowing what other people know. We humans do it. And that’s why we can coordinate in hundreds of ways. In the coral, it’s just hardwired. They coordinate that way, but that’s the only thing they coordinate on and the only way they coordinate. Another example just from the animal kingdom, eye contact. Which in humans, but also in other species, is a very potent signal. It’s most often a threat. The alpha stares at the beta and the beta looks away. If they make eye contact for more than a few seconds, then they’re going to fight. Or, it can also be a mating signal. My late colleague at Harvard, Irv Devore, used to tell his behavioral biology class, “If two people anywhere on the planet look into each other’s eyes for more than six seconds, either they’re going to have sex or one’s going to kill the other.”

LEVITT: So wait, what’s special about eye contact?

PINKER: Yeah, so eye contact is psychologically potent I argue because it is the ultimate common knowledge generator. Namely, you’re looking at the part of the person that’s looking at the part of you that’s looking at the part of them looking at the part of you and so on. You’re committed to playing some strategy in whatever game you’re now embroiled in. It could be a game of dominance and submission, what biologists call the Hawk-Dove game. A major finding of evolutionary game theory in particular is that there is some coordination in threats, encounters, where if a fight would injure both the winner and the loser, they both have a common interest in avoiding the fight and the weaker party seeding the contested resource to the stronger one. And that only works if each one knows that the other one is playing the appropriate strategy. That is, the hawk stands his ground because he knows the dove is going to give way and the dove gives way because he knows that the hawk is going to stand his ground. So that is often signaled in signs of dominance, that can be strutting around or inflating a pouch or puffing out your cheeks. But it can also be a direct stare. Conversely, when the direct stare is reciprocated, when the subordinate doesn’t look away, they both want to play hawk, and that’s when feathers fly.

LEVITT: Let’s say I’m standing in a long line and someone just decides to blatantly cut the line. I think what I’m hearing you say is, if that person cuts in front of me and then they turn and they stare directly at me and I stare directly at them, then we have established common knowledge that they cut the line and that they know that I know that they know that I know that they cut the line. Whereas if they keep their back turned to me and they just cut in line, then I’m pretty sure that they know that they cut the line and they’re pretty sure that I know, but somehow it’s much easier to live the fiction that, Well, maybe it was an accident. Is that what you’re saying with eye contact?

PINKER: That would be a good application. The eye contact establishes the new normal. In this case, Don’t mess with me. I get to cut in line when I want. Now, of course, if the subordinate doesn’t accept that and then stares back, then you can get what the police call, “an altercation of relatively trivial origin.”

LEVITT: I loved your discussion in the book of laughing, crying, and blushing. Could you explain how those things fit into your broader theory?

PINKER: Yeah, it’s in the same chapter as a discussion of eye contact. The chapter’s called “Laughing, Crying, Blushing, Staring, Glaring.” All of them — they’re kind of body language or body signal that isn’t just facial expression. Isn’t just moving the muscles on our face, like smiling, frowning, grimacing, and so on. When you laugh, your breathing is interrupted. You make these raucous staccato sounds. When you cry tears overflow your eye sockets and trickle down. When you blush, blood goes to your cheeks. What I suggest is that what’s special about those together with eye contact is they generate common knowledge. When you’re blushing, you know you’re blushing ’cause you can feel the heat in your cheeks and other people can see you’re blushing ’cause they see the reddening of your cheeks from the outside. And what makes blushing so painful is you know that other people see you blushing. And they know that you know it, that’s why they say, “Oh, you’re blushing!” Which can actually make people blush even if they’re not blushing.

LEVITT: It seems strange because blushing you can’t really control.

PINKER: And that’s true of these other signals as well. Laughter bursts out, you have to repress a laugh. You can’t hold back tears. They are involuntary. In the case of blushing, what common knowledge is being established? You’re basically saying, I know that in your eyes, I have screwed up, I have breached some norm of decorum or behavior or politeness. By confessing that I know that I’ve screwed up, at least I’m acknowledging that I know what the norm is. I’m not a psychopath. I’m not a weirdo. I’m not a loose cannon who just doesn’t even know what the rules are. The rules that you and I share, I know what those rules are. I know I just broke them. At least in your eyes I know I’ve broken them. Because people often blush, even when they’re innocent, if other people think that they’re guilty. These are minor infractions, like commanding too much attention, or something embarrassing like, inadvertent boasting or a confession, passing gas. The blush says, I am caught red-handed, or in this case red cheeked. I know that there is a rule that I’ve broken.

LEVITT: Do you think that blushing is evolutionarily rewarded or you think it’s just some accident that happened along the way to blood flow being good for other stuff?

PINKER: Ironically, Darwin himself thought the latter. He thought that blood just goes to whatever part of the body you’re thinking about. But I think most scientists who study expressions would say that it does have a function that is, it was selected by evolution. Blushing is endearing. And I’m sure we’ve had the experience that it’s really painful when we blush, but we’re often charmed when someone else blushes. It makes an implicit apology credible. That is, again, to use something that’s familiar to a lot of economists. The problem with just apologizing is it can be cheap talk. That is, Yeah, of course you’ll say it, it’s in your interest. Why should anyone believe you? But if it is involuntary, then the perceiver has reason to believe that it’s authentic, because you can’t make yourself blush. If you’re blushing, then deep down, you really mean it. You really know that you’ve screwed up.

LEVITT: The power of blushing comes only because we can’t control it. If there were classes in being able to blush on command, your suggestion is that the value of blushing over the long run would be diminished.

PINKER: Exactly. As with crying, I mean, actors can train themselves to cry often by just imagining themselves in a tragic situation, kind of Stanislavski method. But you can’t do it in the same way that you can stick your tongue out. It’s not voluntary. In the case of tears, it originated probably as a form of surrender, helplessness. Going back to our hawk-dove game, it’s basically saying, “Don’t attack me. I’m not going to fight back.” Again, credibly. Analogous to raising a white flag of surrender or throwing in the towel in a boxing match. Namely, it can be in the interests of the weaker party to signal surrender so that the attacks will stop, which can be in the interest of both parties, because even if the bully wins, the bully can suffer a lot of damage in a fight in which he prevails. And so if they know what the outcome is at that point, then it’s in both of their interests to desist from the fighting. And, again, going back to studies of actual crying, in an argument, say between two lovers, often when one of them starts to cry, then the other one knows, Oh, I’ve gone too far. I’ve been too mean. The tearing can call off the aggression.

LEVITT: It’s interesting ’cause certainly crying serves that purpose, but for me as an adult male. I don’t cry very often, but I would say when I do cry, it’s more from being deeply touched by something. (SP^Yes) Do you think those are separate mechanisms or somehow related?

PINKER: It’s a really interesting question, and I do take it up in the book. ‘Cause you’re right, a lot of crying is being touched, being moved. Sometimes you feel the tears well up when you witness, compassion or empathy in others or a poignant moment. And I’m not sure exactly what’s going on, why the signal of surrender should also be used to acknowledge something that is literally awesome in the original sense of worthy of awe. Sometimes people are moved to tears with a stunning mountain or seeing a whale in the flesh. Something that is sublime, exalted, worthy of our deepest admiration. And I suggest it’s the opposite of what makes us laugh, which is often an infirmity, an indignity, a weakness. So one possibility that I entertain is that it’s simply that emotional displays sometimes come in pairs, kind of thesis/antithesis. Darwin actually suggested this. And that crying is un-laughing. It’s the opposite of laughter. It’s possible that we may want to signal to others that we’re capable of appreciating the best that life has to offer. Not as clear why that would be beneficial, but you could imagine that you trust someone or admire someone if they themselves are capable of awe at the sublime.

You’re listening to People I (Mostly) Admire. I’m Steve Levitt. After this short break, psychologist Steven Pinker and I will return to talk about cancel culture.

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In Steven Pinker’s new book, When Everyone Knows That Everyone Knows, he has a chapter titled “The Canceling Instinct,” where he explores academic censorship and cancel culture. I asked him what ideas he was wrestling with in that chapter.

PINKER: So the puzzle that I took up in that chapter is, Why do people feel the urge to censor, to cancel, to de platform, especially in academia, which ought to be the forum in which ideas are expressed? Ideas can be criticized, but why should you be punished? As happens increasingly in academia where people have been fired, shamed, humiliated, driven out for expressing scholarly opinions. As a psychologist, I wanted to get to the bottom of what motivates people to do it. Why do people pile on in social media shaming mobs, sign petitions with hundreds of signatures? There does seem to be a desire to repress certain opinions through punishment, through censorship. We have lots of norms of what you do, what you don’t say in public. How do the norms exist? Well, they’re matters of common knowledge. We don’t have norm police, we don’t have a network of tele-screens with Big Brother watching us 24/7. But conversely, if a norm appears to be flouted in a public forum, everyone has the sense that threatens the norm, and they feel the urge that they, or someone, should prop up the norm by punishing the norm breaker in public. So that everyone is reassured that the norm still holds. And a lot of punishment in human history was a common-knowledge punishment, you know, crucifixions and public hangings and pillories and stocks. And I suggest that it’s an analogous phenomenon in the electronic realm, where if someone flouts a norm, you feel they must be punished in public.

LEVITT: So I think what I hear you saying is that the fact that the norm was flouted in public matters a lot and the implication is that the people who are enforcing the norms, if in a private conversation someone made the kind of statement that you’re talking about, their reaction might be very different. Am I hearing you right? You think that the public nature of the infraction leads the defenders of the norms to lash out in a way that they wouldn’t if it was just in a private email?

PINKER: Yes. I don’t have good data on this. So this is partly anecdotal, and that is that some of the opinions that can get you canceled as an academic are things that I suspect a lot of people believe, including the people doing the canceling. So just an example, it can be close to heresy to say that men and women inherently differ. On the other hand, I’ve heard a lot of gossip about typical male behavior: men posturing over status or hitting on their secretaries or marrying their secretaries. And it’s often a form of private amusement among people who would, you know, hit the ceiling if you said that men and women differ in an academic context. Or another example is people who deny the existence of intelligence. That is a very popular academic view. On the other hand, you get ’em together over a glass of wine and there’ll be a lot of gossip over how smart or not so smart their various colleagues are.

LEVITT: So you, yourself have been the target of cancel culture. The one I’m familiar with is back in 2020, hundreds of linguists tried to get the Linguistic Society of America to rescind some honor that you had received and I think it was because you were tweeting about research that top economists were publishing on race and policing. You tweeted about something that Sendhil Mullainathan, who’s probably my favorite economist in the entire world, that he had written in The New York Times. You’ve probably done some things wrong, but it’s interesting that that was the thing that unleashed the mob on you.

PINKER: It was one of several things. You know, nothing bad happened to me. I mean, even if they had taken away this honor, it would be like one line on my C.V. It’s not a big deal. What made it serious was the message that it sent to less powerful academics, to the non-tenured, to the instructors, the grad students. It’s like, Don’t you dare say anything that goes against the current, hard-left, woke ideology. Even if, as you point out, this is like a academic study, how could it be immoral to cite something that you know might be true? Maybe it’s not true, you criticize it, but why would this be a hanging offense? And that gets to the question of, Why do people often seem so irrational? Why do they blow off science? Why do they believe in conspiracy theories, and quack cures and paranormal woo woo and things that are patently false? What I suggest is that when it comes to big issues like what is the cause of crime? What’s the cause of recessions or depressions or illness? Or why do bad things happen to good people? People who are committed to the pursuit of objective knowledge, academics and journalists, have a conviction that there is a truth out there. There are ways of finding it: the scientific method, fact checking, data gathering, and so on. But this is actually a rather exotic human intuition. Most people don’t feel that in their bones. When it comes to big issues, there isn’t a fact of the matter. Your beliefs are signs of your moral commitments, of which myth you endorse; which story you feel is edifying or uplifting; or makes your side look good and the other side look bad. And beliefs are often signals of tribal loyalty, not of degrees of credence in the objective state of the world. And so that’s what makes possible something that I think you and I both find anomalous. Namely, how can you pass some moral judgment on a claim of something being either true or false? You might be wrong, but you’re not bad. But that attitude, which I think is the ideal attitude if you’re a scientist, if you’re an academic, if you’re a journalist, if you’re a public servant, it doesn’t come naturally to people. It’s more natural to think that what you believe is a sign of whether you’re a good or a bad person.

LEVITT: It’s interesting you say that ’cause I’m just reflecting on the most prominent attempt to cancel me, which happened after Stephen Dubner and I published SuperFreakonomics and we had a discussion of geoengineering. So the idea that ultimately we might need to manipulate the environment using science and technology to try to offset climate change. We didn’t do any original research, we simply cited things that had been published in the most prominent scientific journals. And we had actually talked at great length with many of the leaders in the field. The kinds of attacks that were made were that we were awful people because we were disrupting the norm, which at that time, it was right around the Copenhagen meetings. And there was a sense that the whole world was going to come together, we were all going to decide to do the right thing around the climate. And what’s interesting to me is two things: Economists who should have trusted and known me as an economist, that I wasn’t a total hack without even being able to read the book because it hadn’t even been released yet, dismissed me as having turned somehow to the dark side. Even the climate scientists who had signed off on our chapter, many of them went on to publicly berate us as if we had made everything up, even though they had read the whole thing and said that they agreed with it.

PINKER: That’s a great example because you were probably ahead of your time because I think some of the consensus has shifted. But, yeah, maybe you’re wrong. Maybe there is no harmless way or cost effective way of manipulating the climate. Maybe that’s true, but you’re not a bad person for suggesting it. But at the time it just seemed like you were aligning yourself with the wrong coalition, with the right-wing climate deniers. Ironically, a lot of the remaining real climate denial comes from incidents exactly like what you endured, which can lead actually intelligent skeptics to say, Well, even if there’s a scientific consensus that human activity is warming the planet — which there is — but why should I trust the consensus? If you step out of line, people are going to come down on you with a ton of bricks, call you a bad person, try to censor you. So scientific consensus is worth nothing. We’re not doing ourselves a favor by broadcasting that there’s an atmosphere of, You get punished for venturing certain opinions. Because that just saps the credibility of the entire scientific enterprise if people correctly sense that the process is being perverted by canceling people with unpopular opinions.

LEVITT: You eventually started something called the Council on Academic Freedom at Harvard in 2023. Was your own personal experience one of the things that led you to make that investment?

PINKER: No, no. Wasn’t about me. Probably the last straw was what happened to one of my associates, Carole Hooven, a human evolutionary biologist who was kind of driven out of Harvard for saying in a Fox News interview that biologists have a clear cut definition of the sexes. Namely, there’s a sex that produces big gametes, a.k.a. eggs, we call them female. There’s a sex that produces lots of itty bitty little mobile gametes, we call them sperm; that sex are males. She said something that’s true. But the D.E.I. officer in her department sent around a memo of the transphobic hate speech that she engaged in. When she would speak about her new book on testosterone, people boycotted it. Graduate students refused to work with her as a teaching assistant. And she was an award-winning teacher at Harvard. She was driven out over this bogus accusation that she said something transphobic. And that’s what set a number of us over the edge. That was consequential, unlike what happened to me, which was a silly little blow up with no consequence. 

LEVITT: The name, the Council on Academic Freedom at Harvard, is pretty self-explanatory. I suspect I understand your goals, how do you try to achieve those goals?

PINKER: We weigh in with the university leadership by expressing opinions on things like institutional neutrality, the principle that University of Chicago pioneered decades ago, so-called Kalven Principle, Kalven with a K, that the university should not express opinions on public issues of the day. They should let their students have opinions, their professors have opinions, but the president of the university, the deans, departments should not post their opinion on this, that, or the other thing. We have events like, What is academic freedom? What are the legitimate limits? What is viewpoint diversity? We’ll stand up for someone who’s a target of cancellation. We have a lively discussion group where we try to hash out issues of academic freedom. We write articles in the student newspaper like The Crimson, but also in The Boston Globe, The New York Times where various coalitions of the willing will express some opinion.

LEVITT: At least the examples you gave were all attacks from the left, and I think that was probably the reason that you initially set up the council. It’s interesting and ironic that not long after you set it up, a bunch of attacks from the right, from the Trump administration, really unprecedented attacks on universities, Harvard, in particular, came down.

PINKER: Yes. The Foundation for Individual Rights and Expression, which tallies incidents of of censorship and de platforming and firing, find that most of the attacks from within the university come from the left. Most of the attacks from outside the university come from the right. And I think that pattern continues to hold in most universities — maybe not in ultra-religious Christian universities, but in most. And the attacks on academic freedom from the government have intensified, including the demand that Harvard be audited for its viewpoint diversity, and that a government panel have the right to force Harvard to hire a critical mass of professors to achieve viewpoint diversity and to vet students we admit for loyalty to the ideals of the American Declaration of Independence and Constitution. So, yes, these were all out violations of First Amendment and academic freedom. And Harvard has so far successfully fought them in court.

LEVITT: So you’re one of the staunchest advocates of the view that the world has gotten better and better over time. Is your confidence that progress will continue, is it weakened at all by anything happening around you these days?

PINKER: Well, some things. I do try to track the trends since I published Better Angels of Our Nature and Enlightenment Now. Because it is an empirical proposition. The claims that I made, you know, that’s just the way the graphs go. Extreme poverty declined; literacy improved; homicide declined; maternal mortality has gone down; child mortality has gone down. A lot of them were knocked off by the Covid pandemic: life expectancy, poverty, and so on. But the world’s recovered from most of them. We have really lost progress in war deaths over the last five years because of Ukraine and Sudan and Ethiopia and Gaza. It’s taken us back to the level of the early ‘90s. Democracy, we’ve lost maybe 20, 25 years of progress. Still better off than we were in the 20th century. But backtracking some. I don’t think any aspect of progress is inevitable. It’s the result of human beings seeing problems, trying to solve them. Sometimes succeeding, trying to learn from their mistakes. To the extent that we do that, progress can continue. But to the extent we do stupid things, then it won’t. And I think that a number of things have been colossally stupid. Most obviously the invasion of Ukraine. I suspect tariffs are not going to work in the direction of increasing affluence and decreasing poverty worldwide. The decline in democracy is I think a step backwards; it’s going to have a number of knock on effects. By and large, the progress has continued but there is some backward movement and no guarantee that it will be restored.

LEVITT: I am not usually much of an alarmist, but I will say the two trends that I see, looking really only within the U.S., that are really troubling to me. The first is the anti-science attitude, the idea that truth is less important than belief. And the second one is the breakdown in rule of law. When the government no longer seems to think that it’s guided by the same laws as other people. It never really occurred to me in my own lifetime that the U.S. could descend into some sort of nightmare scenario, but now I do see some possibility, although remote.

PINKER: I share your concern. ‘Cause some of the great ideas of the enlightenment, such as the one that this country was founded on, that government power is not a question of a strong man ruling by charisma and then having the right to impose anything that he wants on the country, but it’s an institution legitimated by the interests of the people and guided by rules, fiduciary duties, rule of law, constraints on executive power — all of which the current administration is oblivious to and trying to undo. The idea that government is a system empowered by a rule of law — that’s not an intuitive idea. What’s intuitive is a charismatic strongman.

LEVITT: I don’t know if you’re in the business of giving predictions. Thirty years from now, world is better than the place we’re living now or worse?

PINKER: Wow. Democracy has been on its heels before, people see that bad things happen. If some of the bad effects of these policies of the move toward authoritarianism become increasingly obvious, one might say common knowledge, then we do have the checks and balances, the guardrails, the ideals of democracy to fall back on. Unlike countries that had no experience with democracy, no historical memory of it, I do think we have the means to recover the momentum toward rule of law, liberal democracy, liberal values in general.

Steven Pinker’s latest book is called When Everyone Knows That Everyone Knowns: Common Knowledge and the Mysteries of Money, Power, and Everyday Life.

LEVITT: This is the point in the show where I welcome my producer Morgan on to tackle a listener question.

LEVEY: Hi, Steve. So our last new episode was with Seth Berkeley. An epidemiologist who for over a decade ran an organization called Gavi, which is a public-private organization that’s really responsible for vaccinating most of the developing world. I think they’ve vaccinated over a billion children and have saved 20 million lives with their vaccines. We asked our listeners if they had any follow-up questions for Seth and a listener named George sent us a question, and George had a great question. It was about the mRNA Covid vaccine. George was wondering about the efficacy of it. The mRNA vaccine is a little bit different than a more traditional vaccine. The mRNA vaccine is out there and it works, but George is wondering if we should be spending resources now developing a more traditional vaccine for the Covid virus, something that possibly could be more effective than what we currently have.

LEVITT: So in response to what George said, first let me say, I think it’s an excellent question and I actually wish that I had thought of it. It would’ve been a great question to ask Seth during the interview. And Seth gave a remarkable response. I think you probably agree, Morgan, the detail and the thoughtfulness of his response hats off to Seth for doing that, and I think we should put that response in the episode notes so people who are interested can go and dive into it. If I had to capture the gist of Seth’s response, he makes two points about the mRNA vaccines. The first is that they’re very quick to develop, and we talked about that in the episode. In a pinch, they were the ones we were able to get out quickly, and so we naturally gravitated to using them. And the other thing about the mRNA vaccine, which actually goes back to an episode I did with Moncef Slaoui years ago, is that they knew that this was the right kind of approach for the Covid case because Covid is a highly variable changing virus, and they knew from past experience that the mRNA was a good approach for something like that as opposed to measles, which doesn’t really mutate very much. And so the old style vaccines have been really effective on measles and are thought likely to be less effective on Covid.

LEVEY: George brings up another point. As a society, should we be investing and trying to develop another vaccine and testing it head-to-head with the mRNA vaccine?

LEVITT: Seth doesn’t answer that directly, but he hints at it. What he points out is that once you’ve got multiple vaccines, it’s really not in anybody’s interest to go out and try to test them to see which ones are better or not. Being late to the game in vaccines almost guarantees that you’ll never get very much in terms of market share, and it is interesting because George is right that at some level the Covid vaccine worked, but only kind of worked. Shouldn’t we as a society be investing to come up with a really awesome old style vaccine that would really solve the problem of Covid? And part of Seth’s answer is, Well, it’s not that easy to get that vaccine. But I think a deeper economics take on it is, Look, there are always trade-offs and we could invest these resources to try to get this really amazing vaccine, just assuming we could get it, but there are also a lot of other things we want to do and those are real resources that would be used up in doing it. We don’t even know whether a more traditional vaccine would do better than the mRNA approaches. Let me say this, I think about looking forward instead of backwards. What I think we should be doing is not trying to perfect the Covid vaccine, but to start to put in place the basics of a vaccine that would deal with the kinds of viruses that we think could be the next pandemic. I think in the space of people who make these vaccines, there are some pretty good ideas about things that haven’t gotten us yet, but are out there ready to pounce on humanity. It’s the pitch I made at the end of that Berkley episode. That’s the kind of investment in the future that I think we should be making, and I think we will deeply regret the fact that we’re not doing it now.

LEVEY: George, thank you so much for sending in your question. Listeners, send us an email if you have a question for Steve Levitt or an issue that could use an economic solution, or just a thought about our show, our email address is PIMA@Freakonomics.com. That’s P-I-M-A@Freakonomics.com. We read every email that’s sent and we look forward to reading yours.

In two weeks, we are back with the brand new episode featuring Nobel Prize-winning chemist Frances Arnold. The techniques she developed for applying directed evolution to enzymes have been massively influential. As always, thanks for listening and we’ll see you back soon.

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People I (Mostly) Admire is part of the Freakonomics Radio Network, which also includes Freakonomics Radio and The Economics of Everyday Things. All our shows are produced by Stitcher and Renbud Radio. This episode was produced by Morgan Levey, and mixed by Jasmin Klinger and Greg Rippin. We had research assistance from Daniel Moritz-Rabson. Our theme music was composed by Luis Guerra. We can be reached at pima@freakonomics.com, that’s P-I-M-A@freakonomics.com. Thanks for listening.

LEVITT: That is a terrible place to end. 

PINKER: I know, right? 

LEVITT: I don’t know what to say next.