C (3:31)

It isn't. And common knowledge has come to take on a technical term, meaning within game theory and philosophy and linguistics and economics. So it refers to the state in which I know something, you know it. I know that you know it, you know that I know it. I know that you know that I know that you know it ad infinitum. So in a comedy club and people titter, it is. It can be funny. And it actually has been the subject of plots and situation comedies, perhaps the best known being the episode of Friends where Rachel says to Joey, they don't know we know they know we know. Joey, you can't say anything. And he says, I couldn't even if I wanted to. Which raises the puzzle of how could the concept of common knowledge, which, by the way, refers to that state of embedded knowledge about knowledge ad infinitum. Now, so immediately one has to ask, well, how could that be relevant to anything? Your head starts to hurt after two or three. I knows that she knows, let alone an infinite number of them which can't fit inside a finite skull. But one of the reasons I took up the question is that as a cognitive psychologist, I was interested in how people can represent the state of common knowledge, if they do at all. There's reason to think that we do because common knowledge is necessary for coordination. And that is why it has been of such interest among economists, philosophers, game theorists. Coordination being the state in which two or more people make choices that benefit them both, as long as they both make it. So there's no reason to drive on the right as opposed to driving on the left. But there's very good reason to drive on the same side that everyone else is driving on whichever side that happens to be. And it's crucial that you know that everyone else knows that that's the side that you drive on. Or even something as simple as a rendezvous to meet at a certain place. It's not enough to know that your friend likes to go to Starbucks and. And so you go to Starbucks, because if he knows that you like to go to Pete's, he might then go to Pete's and he might even think, well, wait a second, he knows I like to go to Starbucks. So he won't go to his favorite place, he'll go to my favorite place ad infinitum. Nothing short of common knowledge can guarantee that they'll end up at the same place at the same time. So how do we do it? Given that technically it involves an infinite number of layers? I think if something is public, if it's conspicuous, if it's self evident, if it's out there, if one of us sees it at the same time that we see someone else seeing it and they see us see it, that can generate common knowledge in one intuition, the intuition that something it's public, it's out there, you can't take it back. And that is psychologically the main way we experience common knowledge. So I came across upon the concept when I was trying in a previous book, a case in which an open subject in one book leads to an entire other book. This is in my book the Stuff of Thought. I had a subtitle was Language as a Window into Human Nature. One of the puzzles that I took up was long known to linguists, which is that a lot of the time, maybe most of the time, we don't say exactly what we mean. In so many words, we. So, for example, if you could pass the salt, that would be awesome. Now, that doesn't make a whole lot of sense if you took it literally, because not only would it not be worthy of awe, but why are you kind of entertaining counterfactual hypothetical possible worlds? Why don't people just say, give me the salt, or jeez, officer, is there some way we could settle a ticket here without going to court, doing all that paperwork? We all know that that is a bribe or want to come up for Netflix and Chill. You know, most people know that that isn't in.

B (7:31)

Wait, does that not mean Netflix and Chill? I've been doing it wrong for a.

C (7:36)

Long time, so they tell me. So what's the difference? Why don't we just, you know, kind of cut the crap and say what we mean? And the difference between an innuendo where it's very, very likely that your hearer knows, so there's no plausible deniability, and just blurting it out. What's the difference? What I claimed was that blurting it out generates common knowledge. When you blurt it out, not only does your hearer know what you have in mind, but they know that you know and they know that you know that they know. And since social relationships like a platonic friendship, like supervisor supervisee, like transactional partners are coordination depend on common knowledge. When we don't want to challenge a relationship, we'll sometimes keep something out of common knowledge. It can be private knowledge, but it doesn't subvert the basis of the relationship. So I'm sorry, I've been going on at some length. I did write a whole book about this, but that's how I came upon it, from an interest in language.

B (8:43)

Got it. So if I'm mind reading accurately, I can hear that some people are thinking, what the hell does this pretty interesting but wonky, nerdy concept actually have to do with real life? Because I've read your book and I've heard you talk about it elsewhere, I think there's an example that everyone can register, that can help people register its importance. I was commentating at CNN for the past between 2022 and 24, and I would notice every time the topic of Joe Biden's age came up, it seemed very obvious to me that Joe Biden was like, if he were my grandfather, we would be telling him, you can't drive anymore and all this kind of stuff. And then not only that, I would look at the polls and it would say things like, 60, 70% of Americans believe Biden is too old to be president. And then when we would talk about it on tv, I would say, hey, maybe Biden's too old to be president. And everyone would say, what are you talking about? He's doing backflips in the White House. And then the interesting part is that Joe Biden's bad debate performance to me seemed like everything Joe Biden had been, it seemed identical to his performance over the past year. But something changed overnight. What is it that changed?

C (9:57)

No, it's a great example. And what changed was now there was common knowledge of what previously had been private knowledge. So indeed, polls showed that a large percentage of Americans thought that he was cognitively unfit to be president. But they didn't necessarily know that everyone else knew that what happened during the debate, because it was something that was watched. Not only was it watched by a large audience, but the large audience knew that it was a large audience, it was national tv, and that then everyone realized at a stroke, everyone knows what I privately knew. And indeed, the percentage of Americans who thought he was cognitively impaired, it did go up by a few percentage points, but only a few percentage points because it was already a majority, but everything changed when it was now common knowledge. Again, there was a coordinated response, whereas previously there had been just scattered opinions. And in general, any highly public event has the capacity to generate common knowledge. The paradigm case and the way I begin the book is the story of the Emperor's new clothes. Because when the little boy said the emperor was naked, he actually wasn't telling anyone anything they didn't already know. They could see the emperor was naked. So what changed? Well, at that moment, now everyone knew that everyone else knew that everyone else knew. And crucially, the common knowledge changed their relationship with the emperor from obsequious deference to ridicule and scorn. That is, it changed the relationship of authority, which like all relationships, I argue is held in place by common knowledge and can be challenged by a change in common knowledge.

B (11:40)

Yeah. So to get why this is a profound concept, you really have to cement in your brain that like 90% of humans everywhere could know something and it's still not common knowledge until suddenly they know that everyone else knows it. They know that they're in the majority. Right. So that's the difference. I'm going to run some situations by you that might relate to common knowledge and you tell me if you think they do so when people are states are negotiating in like a sensitive behind the scenes negotiation, think you know, Arafat and Ehud Barak negotiating over Israel Palestine in 2000. We know they're both so fearful of a leak, in other words, the prime minister of Israel might be currently negotiating that I'm going to give up this big thing, that a lot of this painful concession. Arafat may think the same thing, but if it comes out that he's ready to give that out, he can no longer give it out. And it's a strange paradox because he, you know, if the deal were achieved, he would go home and say we split Jerusalem in half. Right. But if it leaks that he's about to split Jerusalem in half, he can't split Jerusalem in half. So does this relate to common knowledge in any way or is this something else?

C (12:54)

It's a great example. I hadn't really thought it through, but it absolutely must. I do talk about the fact that governance and in fact any relationship depends on a certain amount of secrecy. One might even say hypocrisy. I think none of us would want there to be hidden microphones or telescreens with the Stasi eavesdropping our conversations at home, even though we're really not guilty of plotting anything. But you say A lot of things, even about your close friends, your boss, that you really would not want to be public. Because social relationships depend on common knowledge. Things that might be privately suspected are very different when they're out there, when they're leaked. So in the case of negotiations, probably what's driving that crucial difference is that broaching a concession is a sign of surrendering dominance or authority or face. That is, it's signaling weakness. It's signaling a willingness to back down in a confrontation. And confrontations are often resolved by the dominant one knowing that the subordinate one is going to back down, and the subordinate one backs down because he knows that the dominant one will hold his ground, which he knows because he knows the subordinate will back down ad infinitum. It's common knowledge who is the alpha and who is the beta. And any concession before it actually is consummated as a deal can be seen, especially among people in the same coalition, as a willingness to surrender dominance, to lose face, to back down, and therefore to have forfeited an advantageous negotiating stance in the future.

B (14:50)

Next question. Are you an alpha or a beta? I'm kidding. Don't answer that. So, over the past few years, I can't remember when I first heard this term, but I'm sure many will be familiar with the term dog whistling. The idea that a political commentator or someone on cable news is saying something that's kind of a coded message to his particular base, but is meant to sound innocent enough for the rest of the world to not realize, wink, wink, what he's getting at, which group he's talking about, and so forth. Does this have to do with common knowledge at all?

C (15:25)

Yeah, it does. It is a way of avoiding common knowledge. And it can even be that if the dog whistle is recognized as a dog whistle, it can still be more effective than just blurting something out. Because again, what can be widely distributed private knowledge, or at least private with, specific to one group, not common across groups, can then maintain the relationship of status or face saving between them. So even if it is, if you highly suspect that it's a dog whistle, there can still be a different psychological status than if it's blurted out overtly. Then if you accept it without challenging it, without confronting the person, you haven't surrendered your bargaining position.

B (16:19)

Okay, Another example might be political apologies. I think there's this interesting dance. Anytime a politician does something wrong or something that many people think is wrong, that some people would say, well, why don't you just apologize, just acknowledge you messed up, and people will forgive you. But I think a lot of politicians have the instinct that if I apologize, that will actually somehow make it worse. And could this possibly have to do with common knowledge? Because an apology is sort of like a recognition that everyone knows that everyone knows that it's wrong and rather than it being sort of up for debate, even if most people did think it was wrong.

C (16:57)

Yeah. So apology has a different function when you talk. In one of the chapters in the book, I categorize human relationships into three broad types, drawing on a theory from the anthropologist Alan Fisk, who did a cross cultural survey. There's communal sharing or communality. We're all brothers. What's mine is thine. Share and share alike. There's authority. Don't mess with me. And then there's reciprocity or equity. Tit for tat, even Stephen trading. We're very psychologically attuned to what relationship we have. I think an apology in the context of a communal relationship, a couple or a friendship can cement the relationship. It means that you don't have grounds for defecting. When someone has tried to claim an unfair advantage, you don't bail out. If they apologize, they've given some clue that they know that they have messed up or taken advantage of you and they won't do so in the future. So you have reason not to bail. In a relationship of dominance, if that's what the leader is trying to reinforce. Apology can be a loss of face, an inability to stand his ground in the future with the confidence that the other person will give way. And I think that's when you get into the situation of. Was it Admiral Nelson who said, never apologize, never explain? Bad advice. If you're in a relationship, if you're in a marriage, contra the old cliche from the movie Love Story, love means never having to say you're sorry. That's not very good advice for a romantic relationship.

B (18:51)

Okay, our read receipts. You know what read receipts are?

C (18:56)

Yes.

B (18:56)

Yeah.

C (18:56)

Yes. Okay.

B (18:57)

Just make sure. Are read receipts an example of common knowledge. And what does it mean when you turn on your read receipts with someone as opposed to not having them on?

C (19:07)

Yeah. There was actually reproduced an ad for the now defunct BlackBerry smartphone and the caption was, you'll know they know you know they read it. Which I actually find rather terrifying. That is the read receipt was the default as opposed to something that we request that was supposed to be an advantage. Maybe that explains why they went out of business. But yeah, there is a big difference. And there's a famous theorem in the literature on common knowledge that actually no number of read receipts suffice to guarantee coordination compared to being on the same page having the synchronous conversation. Because you could always wonder, they got the read receipt, but did they know that you know that they got the read receipt? You have to send a read receipt for the read receipt. And one of the reasons that the definition of common knowledge is that it has to be an infinite number of layers of I know that he knows. Is that no finite number of read receipts actually establishes the coordination with certainty.

B (20:16)

I remember the example from the book. To make that more concrete, it's like you and I are generals with different factions in an army. We know we can beat these guys, but only if we attack together. So I send you a message saying, I'll attack if you attack. And you say, okay, I'm ready to attack. But I don't know if you've gotten the message yet, right? And then you send me a message, and you don't know if I've gotten the message. That you've gotten the message. That I've gotten the message. And so we never have the confidence to strike unless you have something like cell phones or simultaneous communication, right?

C (20:45)

That's exactly right. And it is a famous theorem of. It was originally called the electronic mail game to refer to kind of read receipts for electronic mail. Also called the coordinated attack problem. And I think it does have manifest. It has a lot of manifestations. Why sometimes it's so hard to say goodbye. Like, you hang up first. No, you hang up first. No, you hang up first. She hung up on me. Or if you're pedestrian and you're stepping on the. And a car stops not at a red light, but courtesy to let you pass, and you don't know whether you should go or. Because, for all you know, the driver might think you decided not to go, and so then he'll gone. He might think, well, you've decided to let him pass. Which is why I reproduced a sign that I saw in San Francisco airport that says, at the zebra crossing, it says, make eye contact with the driver. And eye contact is a quintessential common knowledge generator. Because 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 ad infinitum, implicitly. And so eye contact, it's a potent signal, in this case of just mere coordination. We agree. Pedestrian can cross, car will stop. But eye contact is also a potent generator of common knowledge. It's as in, can you look me straight in the eye and say that or the barroom taunt you looking at me. My late colleague at Harvard, Irvin Devore, the anthropologist, used to tell his introductory behavioral biology class, if two humans anywhere on the planet look into each other's eyes for six seconds or longer, then either they're going to have sex or one's going to kill the other one. So eye contact doesn't have a suit. I actually tried that with my class and after five seconds I say stop, stop. But in the pedestrian crossing case, it's merely to coordinate a simple plan, but hardwired into us because eye contact is also a threat signal in other species, in many primates and in canines as well, that it can have a hardwired function as well. In humans, it's more generic. It's something that has hitherto been private knowledge is heretofore common knowledge. That's why eye contact is so potent. And it's one of a number of non verbal signals that I deal with in one chapter of the book called Laughing, crying, staring, blushing, staring, glaring displays that I argue are common knowledge generators. Namely, they are potent because the expressor feels them from the inside at the same time as he's displaying them from the outside, knowing that the perceiver knows that he's experiencing it from the inside again ad infinitum, but in one fell swoop.

B (23:55)

I'm blushing right now. You just can't tell. Okay, so let's talk about how common knowledge relates to authoritarian regimes. So you talk about in the book how we're thinking of places like North Korea, Cuba, Venezuela and Soviet Union under Stalin. Places where it can be just like 70, 80% of the population can be dissatisfied. And if they all rose up together, they'd be able to topple the regime. But it cannot happen for, you know, 50, 100 years. So how does that relate to common knowledge?

C (24:33)

Yeah, there's a. I quote a line from the movie Gandhi where the Gandhi character says to a British officer, in the end, you will leave. Because there is no way that 100,000 Englishmen can control 350 million Indians if the Indians refuse to cooperate. He could have said refuse to coordinate because indeed 350 million Indians can overpower a regime of 100,000 colonial officers if they all stand up at the same time and refuse to work or storm the palace. The problem being, how do they coordinate given that common knowledge is necessary for coordination? Well, that's why dictators try to prevent common knowledge. It explains why they censor, why they clamped down on public demonstrations because a widely circulated article or even slogan generates common knowledge. If everyone knows that, everyone hears it, now can be the time that everyone stands up at once, whereas individually, they might be afraid of being picked off one by one. So it's why freedom of assembly is considered a fundamental right in a democracy and why dictatorships forbid public rallies. Likewise a public dissemination of information. I reproduce a joke from the Soviet Union in which a man is distributing leaflets in Red Square, and of course, the KGB arrest him, take him back to headquarters, only to discover that the leaflets are blank sheets of paper. They confront him, they say, what is the meaning of this? He says, what's there to say? It's so obvious. Now, the point of the joke is he was generating common knowledge. That is, he didn't have to say anything. The mere fact that he was distributing it, that people were accepting it, meant that people now knew that they were not the only ones disgruntled with the regime. Moreover, that even if everyone suspected that everyone else was disgruntled until they had grounds for believing that everyone knew that everyone else knew they would not have the confidence or the coordination to oppose the regime in unison. And in a case of life imitating a joke, a few years ago, Putin's forces arrested a man for holding a blank sign as if they had heard the joke.

B (27:01)

And along those lines, there was a very interesting and counterintuitive fact about the Chinese Communist Party and the way they do censorship in your book.

C (27:10)

Yes, from my colleague Gary King, who did a study, managed to infiltrate hundreds of thousands of social media posts and which ones were censored by the Chinese government. And it turned out it was not complaints against the regime. In fact, they used those as kind of inside intel as to which of the commissars wasn't doing his job at placating the masses. But what they did stomp on was any attempt to coordinate people having a meeting, sharing information, sharing news about a new bulletin board, anything that would allow people to get together is what they came down on like a ton of bricks.

B (27:53)

Right. So they actually want real private feedback to avoid people getting disgruntled. They just don't want people to meet in the town square.

C (28:00)

Exactly. Or the electronic equivalent.

B (28:02)

Yeah. Right. So if you think about the Arab Spring in 2011, where you. You basically, you have one Arab country rises in revolution, demands democracy, and then all these other Arab countries follow suit in short order, is this an example of common knowledge and salience?

C (28:23)

Yeah, it is. And it all the. One of the remarkable things about the Arab Spring is that all began on what would seem like, with what would seem like a rather isolated incident. A Tunisian fruit peddler who was harassed by the authorities and set himself on fire in protest. That started a chain of events that led to regime change in a variety of countries, then eventually to one of the worst civil Wars in the 21st century, the Syrian Civil War. Just one guy setting himself on fire. So what was the deal there? And in between, there was the role of social media, of Facebook and Google spreading the news that now was the time to rise up. So the Tunisian fruit peddlers, an example of a phenomenon that I call the communal outrage. Thomas Schelling, a political scientist who deserves credit for a lot of the ideas behind common knowledge, discussed it way back in 1960. More recently, John Tooby has written about it. This is the case where there's one incident that that is interpreted not as an attack on an individual, but an attack on an entire class of people. And it can often be the signal that allow people to rise up in rage as if the event is an absolutely intolerable insult against the entire group which may not be allowed to stand. And you can get cascading events way out of proportion to the original event. So examples are Pearl Harbor, 9, 11, George Floyd, the sinking of the Lusitania, the explosion of the USS Maine. Sometimes the event can be apocryphal, like a rumor of Jews sacrificing a Christian boy to make matzah from his blood. But the idea, once it spreads, that this even happened, can coordinate people in often a ferocious attack against the group that they see as the perpetrators of the initial atrocity. In the case of the Tunisian fruit peddler, it was the regimes of the Arab countries. It's not exactly revenge, because revenge has to be proportional and directed to the perpetrator, but it's more like calibration of a group wise dominance, hierarchy, who's alpha and who's beta. When what might seem like a signal that the beta is consigned to permanent beta status decides, we're not going to take it. The whole world is watching. We may not let this affront go unavenged.

B (31:17)

So I want to propose a different reason why regimes might persist. Even though everyone is dissatisfied with the regime and has common knowledge of it. So suppose everyone does have common knowledge in your sense, that the regime has to go, but everyone is afraid to be sort of the first person in the crowd that takes the bullet. And so no one jumps at the front of the line. So the line never forms, as it were. Is that a separate reason why regimes can persist for a long time? Or is that similar?

C (31:52)

I think it is part of that that story because it is. You put your finger on again a coordination problem, like meeting up at a cafe or driving on the right, where everything changes if everyone does it at the same time, makes the same decision. In this case, it's say to show up at a certain time at a certain place, to stop work at the same time, to storm the palace at the same time. The coordination problem is how do you get everyone doing it at the same time? Because, as you note, one person standing up can get picked off. 350 million people doing it at the same time. They have the safety in numbers, but only if they're coordinated. If they're discoordinated, then they can be picked off, right?

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B (33:40)

So if you think of the Arab Spring example, where a democracy uprising causes a democracy uprising in the neighboring nation, which causes it in the neighboring nations, and so forth, this is all the result of common knowledge in some sense. Doesn't that make the Cold War domino theory in retrospect, less ridiculous than it's sometimes made out to seem? This is the theory that if one country went communist, then the neighboring country would go communist. And this obviously justify the war in Vietnam and war in Korea and all this stuff. So is that related to common knowledge?

C (34:15)

It can be, in the sense that common knowledge is. I've referred to this a number of times obliquely. Well, in general, common knowledge is necessary to have an equilibrium in coordination games, that is where it's in the interests of both parties to make complementary choices. It doesn't determine what the choice is, but as long as they make the complementary choice, they're both better off. And that can happen in a confrontation, in a game of chicken, for example, or what biologists call a hawk dove game, where if the resource, contested resource isn't worth fighting over in the sense that both the winner and loser of a fight can get injured and suffer a greater cost than what they were fighting over, it can pay both of them for one to back down and the other to get his way. Which is why there are pissing contests and face saving confrontations and road rage. People seeming to fight over nothing, they are actually fighting over something which is who in the future will stand as ground, who will back down, given that it's in both of their interests to avoid a fight. Now sometimes they don't avoid a fight, they both do get hurt. But the status, the pecking order, the dominance hierarchy is a tacit agreement that one will back down, one will hold his ground. And so there could be a case where having admitted defeat, it is a concession that the next country is not worth fighting over. And I think historians could disagree over whether the domino theory was actually vindicated by the fact that not only did Vietnam fall to the, to the communists, but so did Laos and Cambodia, although the domino stopped there and it did lead to. It wasn't a domino effect in the sense of Indonesia fell and Burma fell and so on, but the United States was humbled throughout the 70s and was said to fall into a Vietnam syndrome where it did not strut its stuff on the world stage as much and did lose face and therefore implicitly was willing to back down in other confrontations. One could argue, for example, that the Soviet invasion of Afghanistan was enabled by the fact that the United States backed down in Vietnam.

B (36:42)

So to what extent do you believe in the concept of a Pax Americana, meaning that in the post World War II Age When we showed ourselves to be the most dominant military in the world, that that's paid a peace dividend by deterring countries from invading other countries on the assumption, right or wrong, on the, on a, on a probability that America might come in and police the situation, and if America were to, were to eliminate that role in a, in a conspicuous way, that we'd see a lot more violence in the world?

C (37:18)

Yeah, I do see it somewhat differently because if you actually look at the track record of the United States as a kind of global policeman or global hegemon. It actually didn't do so well. Lost in Vietnam, Soviets invaded Afghanistan. Eventually they withdrew because they lost a war of attrition with the Afghan resistance.

B (37:45)

They.

C (37:47)

Didn'T stop the Iran revolution, including kidnapping American diplomats in the embassy. Didn't do so well in Afghanistan. Even in Iraq, the goal of setting up a stable democracy did not fail. Americans left Beirut after a terrorist bombing of an apartment tower that killed 200 and something American servicemen. America left Somalia after American soldiers were dragged through the States. There aren't actually a whole lot of cases in which the United States was a successful either cop or bully. I think there was such a thing as a liberal post war order, but it was more of a norm that was held implicitly by many, if not most countries. And if anything, the United States was the rogue state in invading Iraq, for example, without authorization of the Security Council. The idea being, the norm being, and in fact a norm that was actually signed onto by any signatory to the United Nations Charter, that war of aggression was no longer acceptable, that international borders were grandfathered in, states were immortal, and, and that disputes could no longer be settled by military force and have the rest of the world recognize the conquest. So that was the understanding. It was a norm. It was held in place because everyone believed that. Everyone believed it. There really was no global police force or hegemon to enforce it. But you just didn't do it because you knew that you just didn't do it. Obviously, Russia's invasion first of Crimea and then of eastern Ukraine absolutely flouted the norm. The open question now is can the norm survive that breaching or does that mean the norm no longer exists? Norms can survive some degree of threat, some degree of kind of hypocrisy. Well, yeah, someone broke it, but we all still understand that it's in place. But it can also unravel. And we are, I think, at a hinge in history or we just don't know which way it'll go. But I don't think that American dominance was what enforced the norm. On the contrary, it often flouted it.

B (40:15)

So to make the counterargument, I would say that, you know, I could, you could argue you're cherry picking in the bad direction. And if I were to cherry pick in the good direction, I would say that you've got the war in Korea, where the country of South Korea probably wouldn't exist without America's intervention in that war. You've got the intervention in Kuwait pushing Saddam out of Kuwait successfully.

C (40:39)

Well, Interesting. There was a multilateral coalition there, and it was authorized by the un.

B (40:44)

Although. Yes, but in Korea, that was a fluke because the Soviet Union happened to be boycotting the Security Council over unrelated issues. Really? It probably wouldn't have. You got Liberia, where you had Civil War for 12 years, and then America shows up with 2,000 Marines and it's over within a week and it's been at peace for 20 years. You've got NATO bombing, and that wasn't authorized by the Security Council. And then you've got NATO, obviously the Balkans, both NATO interventions, which were multilateral. So how do you price the other data points into the theory that it's more international norms than American power?

C (41:25)

Yeah, you have a point there that American muscle did in certain occasions. Suez might be another example in 1956 where American. There was kind of soft power, made a difference. But it was, you know, if you add them up. So it would not be. You're right that there are cases where American power made a difference, but many cases in which it didn't or went in the wrong direction. So I think it wasn't just the United States, but rather a common understanding which sometimes enforced. And it was because of this common understanding that the United States sometimes felt emboldened to intervene, as in Kuwait. That would be the most blatant case. But that it would be hard to, given the entire track record. It would be hard to say that it was a Pax Americana, given how many wars the United States was embroiled in or initiated.

B (42:24)

So then the sort of way of testing this hypothetically would be like, if America just evaporates, do you expect everything else held equal? The number of wars to go up, go down, or stay the same?

C (42:38)

I think evaporating would be a real problem.

B (42:42)

For many reasons.

C (42:45)

If it withdrew from any kind of.

B (42:48)

Cooperation or like we defunded the whole military, let's say, like J.D. vance gets elected and does what the left did to the police, to the whole military, you know?

C (42:57)

Yeah, yeah, I think that would be, you know, I think the world would be more dangerous, but that would also be true of every other country if the rest of NATO, for example, dissolved its military and if there was no longer any alliances or understanding that the countries of the world opposed armed aggression. I think if it was just the United States, there would be enough Somalias, there'd be enough Vietnams, there'd be enough peace movements or isolationist movements of the left and the right that I don't think it would suffice to police a world Order.

B (43:43)

So let's talk about something that I think is on a lot of people's minds that happened last week, which is the assassination of the conservative activist and speaker Charlie Kirk. I'm curious, you're someone that's written a lot about political violence. Not only how violence has declined over American history and world history, but also how, you know, how the world made war illegal and how we've become more peaceful societies. So what is your reaction to the assassination of Charlie Kirk and also what is your reaction to the reaction, to use a little common knowledge recursiveness there, of course.

C (44:29)

Well, I think it is absolutely heinous, horrific, horrendous. I'm not saying anything about what I think of what Charlie Kirk himself advocated because it's completely irrelevant. That is the very idea of silencing a voice, of committing murder is just self evidently horrific. It is true that for a lot of human history, the way that people dealt with voices they didn't like, especially if they thought they were generating common knowledge, is that they were a danger and therefore had to be silenced for the greater good. The mild form is called deplatforming. And again the metaphor. We have a lot of metaphors for common knowledge in terms of something being visible, public, conspicuous, salient. Conversely, the notion of deplatforming is a platform is where everyone sees someone, everyone sees everyone seeing something. So the soft version of censorship and disinvitations are one version and then the horrendous version is literally killing someone to prevent their message from becoming common knowledge. And one of the achievements of democracy is you don't have to physically silence someone to counter their message. You argue back. There was one hopes that even with these rather disturbing statistics that a third of Gen Z say that it's okay to use violence to stop a speaker. At least in some circumstances, a rise from other generations doesn't usher in an era where assassinations are considered an okay way of preventing the spread of dangerous common knowledge. I grew up in an era of far more frequent assassinations than we've had in the past few decades. When I was a child in the 60s, in close succession there was Medgar Evers, Malcolm X, JFK, RFK, Martin Luther King, and some attempted assassinations that people forget about. George Wallace. In 1972, President Gerald Ford was the bizarrely the target of two assassination attempts, both by women. Does anyone recognize the name Squeaky Fromm? So Gerald Ford, of all people, kind of a mild mannered, not particularly divisive president, was shot at twice. Both who miss Ronald Reagan was shot at and John Lennon. So it actually did die down the rate of assassinations. It's too soon to say whether that decline will pick up. There are some disturbing signs. And all the more reason that it should be denounced by all sides of the political spectrum.

B (47:27)

We're here at the Comedy Cellar. I'm curious if comedy, obviously, the purpose of comedy, I think, is to be entertained, to make us laugh, to make us enjoy our lives a little bit more. But as a side effect, does it have the effect of sort of constantly puncturing small spirals of silence? Because you can imagine, and I think having gone to this comedy club, long before you could say out loud that Joe Biden was too old to be president, comedians were making jokes about it. And the thing about the joke is, okay, the joke is made, but once the whole audience laughs at a joke, now everyone in the audience knows that other people know that they know that you all know at the same time that you all found the joke funny. And crucially, laughter is involuntary. So you actually can't. It's very hard, especially if you have half a drink in you. It's hard to choose not to laugh at something that is, in fact, funny to you. Whereas you can pretend to think someone's point is a bad point, even if you think it's a good point. That's very easy to do. And so is comedy sort of constantly puncturing these spirals of silence?

C (48:41)

Absolutely. That's perfectly explained. And I can't help but notice that here we are in the Comedy Cellar, and right over there, there's a drum kit. And I assume that's there for the bada bing at the end of a joke. Like, my wife likes to talk during sex. She calls me up and she says, nathan, I'm having sex. That's from old Jews telling jokes. It invites a bada bing. The bada bing is a little bit like the conspicuous staccato sound of a laugh. And laughter is contagious. That's why there's the drum kit. That's why sitcoms used to have laugh tracks, and why there's a rumor that comedy clubs used to hire someone with a really loud, raucous laugh to sit at the back and laugh at the comedian's jokes, because that would generate the laughter. So, yes, laughter is indeed contagious, and it is conspicuous auditorily. But also, if you're the one laughing, it interrupts your speech. So you know, you're laughing, you're making a noise that other people can hear. You know, they can Hear the noise, they know that they're laughing, but that you're laughing by the fact that you've interrupted your speech. So it's one of these common knowledge generating signals. And indeed I think its purpose is as a kind of counter dominance signal. Many species that have pecking orders and alphas also have counter dominance because, you know, if you're always the, you know, the gamma or the delta, you want some way of shaking up the pecking order. And they're called counter dominant signals. And that's often what laughter does. It points out a common indignity or infirmity and it can be used aggressively to bring down an alpha, although it can also be used convivially. If the relationship is not authority, but rather communality. Among a group of friends, there's an awful lot of laughing that is good natured self deprecation, gentle teasing, where the idea is also to level of hierarchy, not to bring someone down, but to keep everyone on the same level. That's the basis of friendship. Friendship is based on the common understanding, one might say, even the myth of complete egalitarianism. That's what friends are. No one lords it over anyone else. And since in reality no two people are identical in talent or looks or intelligence or humor or anything else, to keep the friendship, a friendship, you often want to negate any signal that would make one person have a reason to lord anything over the other. And so you make fun of yourself, you tease your friend and that keeps friends friends. And again, laughter does that. And one of the signature findings, and it actually is a science of laughter, There's a guy named Robert Provine who died a couple of years ago, who went out into social gatherings with a mic and he just recorded what makes people laugh. And it turns out contra the what we're what's typically experienced in a room like this of jokes and deliberate attempts to maximize humor. Most laughter is not in response to anything particularly funny. You can try this next time you're just with friends. Someone laughs, just pay attention to what made them laugh. It is rarely a joke. It's usually something that out of context is not funny at all. Like you can't mean that or are you kidding? Or that was how my day went. And it generates laughter. It's usually in response to some indignity, breach of decorum, breach of routine that brings you down a little bit, which in a convivial setting is what helps establish kind of egalitarianism. But it is public, conspicuous and it is the signal that allow you to coordinate on that relationship.

B (52:46)

Okay, my final question. Is there anything in any synthesis of your research on common knowledge that generates a tip or a few tips about how to have better friendships? Maybe you just answered it. Relationships. Anything I can take home as a tip about how to use this knowledge in my day to day social life, I guess.

C (53:09)

The final chapter is called Radical Honesty Rational Hypocrisy. And it is about the contrast between some movements to let it all hang out blurred everything out, usually leading to a kind of a hellscape. Conversely, why we all kind of know that if everyone was honest all the time, it would really be awful, that we should be thankful.

B (53:38)

It would be very fun for like five days. And then you'd have no more friends, no more relations.

C (53:42)

Exactly.

B (53:43)

You'd have to start all over.

C (53:44)

And it has been worked out in some sci fi episodes and comedies like Liar, Liar, the the movie with Jim Carrey. What would happen if someone were forced to be or everyone were forced to be completely honest? And the reason is that our relationships, our romance, our relationships of respect and authority, our friendships are held in place by certain common assumptions, fictions really. But that can be blown up if the violations of them were made common knowledge. Which is why there is so much euphemism, tact, social skills, savoir faire diplomacy, where we keep things out of common knowledge to protect our relationships while sending the signals that sometimes have to be sent in order to get something done. So two friends, even just a simple example in a conversation, you know, at one point what would be true? Correct would be, you know, I value our friendship, but you know, up to a point I'm getting our, you know, it's fun talking to you, but, you know, now I've really kind of had enough and it's time. There are other things that I'd really rather do. Now that's often true and probably both parties, if they're grown ups, know that it's true. But it's really different if you say it. And there are all kinds of things that both parties know where everything changes if you make it common knowledge. If you say so. This doesn't mean be hypocritical about everything. It doesn't mean never confront someone over a situation of genteel hypocrisy that's putting someone at a disadvantage. But just to be mindful that some degree of hypocrisy, tact, politeness does serve a purpose in maintaining our relationships.

B (55:41)

So don't go full Larry David.

C (55:43)

Got it. Okay.

E (55:50)

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