ADI IGNATIUS: All right, so, Steven, thank you for being with us today.

STEVEN PINKER: Thanks for having me.

ADI IGNATIUS: Great. So your book is about common knowledge, what it is, and how we use it, and in ways that we're aware of, and in ways that we aren't aware of.

So for the audience, what are you getting at with common knowledge and why should we care about that?

STEVEN PINKER: I'm using the term in a specialized sense, not to refer to conventional wisdom or something that is widely known, but to something that is known to be known.

That is, I know something, you know it, you know that I know it. I know that you know it. You know that I know that you know it, and so on, ad infinitum.

So that's common knowledge in the technical sense.

It's important, because it's necessary for coordination for two or more people to be on the same page to make choices that might be arbitrary, but it works for everyone as long as everyone makes the same choice.

Do you stay home on Saturday or Sunday? Do you drive on the right or drive on the left?

Now, for common knowledge to work, you don't literally have to think, I know that she knows that I know that she knows because your head starts to spin after one or two levels.

And we have a sense of common knowledge when something is conspicuous, or self-evident, or public, or out there.

If I see it while I see you seeing it, then I kind of know that you know that I know that you know it.

ADI IGNATIUS: So this is the Emperor has no clothes.

STEVEN PINKER: Well, I begin the book with the story of the Emperor's New Clothes, because there's a sense in which it's a story about common knowledge.

Because when the little boy said the emperor was naked, he wasn't telling anyone anything they didn't already know.

But he changed the state of their knowledge nonetheless, because by blurting out what everyone could see within earshot of everyone else, at that moment, everyone knew that everyone else knew that everyone else knew that the emperor was naked.

And another point in the book is that just like driving on the right or driving on the left is a solution to a coordination problem, or staying home Saturday, or staying home Sunday, or respecting paper currency, I suggest that our informal social relationships, are we friends?

Do I defer to you? Are we transactional partners? Are we lovers? All of those are matters of common knowledge as well. They're coordination games.

And we solidify them by generating some public signal that we both see that inaugurates the relationship.

But there can be forms of common belief, common misconception, common pretense, where you do have assumptions about what other people are thinking, and vice versa, that in some cases, may not actually be reality.

So in the case of a common pretense, where we refer to that by saying we're ignoring the elephant in the room, the metaphor is that an elephant in the room is something you can't ignore, but we're pretending to ignore it.

There is a phenomenon called pluralistic ignorance, or a spiral of silence.

In economics, it's sometimes called the Abilene paradox, where no one actually believes something, but everyone thinks that everyone else believes it, but no one actually does.

ADI IGNATIUS: Is there an easy example of that?

STEVEN PINKER: Sure, it was originally studied in fraternity, where all the frat guys said privately that it's really stupid to drink until you puke and pass out.

But they said, what can I do about it? All the other guys think it's cool.

And it turns out, none of them thought it was cool, but everyone thought that everyone else thought it was cool.

I think there have been many phenomena like that.

It turns out that in Saudi Arabia, most of the men think that women should have the right to work and drive, but they couldn't allow their wives to do it because they mistakenly thought that all the other men thought that it was impermissible.

ADI IGNATIUS: So I want to lead this conversation sort of mainly into economic, financial sort of market areas, because we are the HBR IdeaCast.

But your book is-- I'd say it's challenging in some ways.

There are a lot of brain teasers. There are a lot of prisoner's dilemmas, things like that.

But it's also fun.

I mean, there are a lot of popular references, jokes, cartoons, and then examples, really interesting kind of game playing examples.

So one of the things you talk about is the Keynesian beauty contest, which, and if I get it wrong, you'll correct me, but where a judge is rated-- a judge doesn't simply select the contestant that he or she thinks is most attractive, but rather is rewarded on selecting, based on what he thinks-- he or she thinks the other judges will select.

STEVEN PINKER: Who are engaged in the same puzzle.

They're guessing what everyone else will judge to be the prettiest face, which is different from the old Miss Rheingold competition, where people voted on the prettiest face.

In the beauty contest that Keynes hinted might have been in the newspapers in his day, this would be London in the '20s, no one can actually verify whether there really was such a contest, but it was a great example.

Because for Keynes, where he said everyone is trying to outguess other people outguessing still other people, he said that's the way speculative investing works.

They buy the security because they think they can sell it at a higher price to other people who think it's underpriced, who in turn, will want to sell it to still other people.

And so speculative bubbles, crypto perhaps being one of the most recent examples, are cases where people think that other people will, in the future, will want to buy in, sometimes called the greater fool theory of investing, that you invest because you think other people will invest because they think that still other people will invest.

The thing is, of course, bubbles can pop when the market starts to run out of the greater fools who think that it will continue to appreciate forever.

But this can all get started when there is some public signal, like in the case of the Emperor's New Clothes, the boy blurting it out, or a public ceremony or a public signal.

Or if there is just a rumor or some reason to think that other people are getting in, that can cause other people to get in.

So a couple of recent examples are meme stocks, where an influencer might talk up a stock, even if the fundamentals are terrible, crummy.

But the fact that other people know that he's talking it up and they know that still other people are talking it up, means that it really can appreciate, at least for a while.

Or in two Super Bowls ago, there were a number of high concept ads for crypto exchanges, which mentioned nothing about the advantages of crypto.

ADI IGNATIUS: These are the Larry David ads.

STEVEN PINKER: The Larry David, the Matt Damon.

Where the point of the ads were everyone's getting into crypto, don't be left out.

And in fact, the punchline to the Larry David comic ad was don't be like Larry. Don't be left out.

ADI IGNATIUS: So this sounds like a tool that people who understand the psychology could and probably do benefit from, right?

STEVEN PINKER: Yes.

And getting back to marketing, I talk about an analysis by a political scientist like Michael Chwe, who's, in some ways, my predecessor in writing a book about common knowledge, where he analyzed the most famous and most expensive ad in history.

This was the 1984 ad directed by Ridley Scott of Blade Runner and Alien fame, ran exactly once during the 1984 Super Bowl.

And it was to introduce the Apple Macintosh.

So it was a revolutionary new product.

Those of us who remember the first personal computers, remember, it had a little screen with 24 lines of 80 characters.

And you had to type in alphanumeric commands like del fubar dot-- fu dot bar.

ADI IGNATIUS: We've come a long way.

STEVEN PINKER: They were clumsy.

So Apple is coming out with this insanely great new product with windows, and menus, and icons, and a mouse.

But they realized that no one would buy it if they thought they were the only one buying it because the price wouldn't come down because of demand.

There wouldn't be a community of users, and experts, and markets for peripherals and consumables.

So how do you break the knot-- cut the knot, I mean, and get people to buy something that they'll only buy if enough other people are buying it.

And the answer is the Super Bowl is an annual rite in American culture.

You know that a lot of people are watching it.

And you know that a lot of people know that a lot of people are watching it.

It is a common knowledge generator.

And to break the logjam, Apple paid for this ad.

It said nothing about the Apple computer.

For those of you who have seen it, it played off the fact that it was January 1984, the date of George Orwell's novel.

And so it showed a grim corporate meeting where gray drones trudge into a cavernous hall and listen to drivel from a voice on the screen, intercut with scenes of a lithe young woman in a bright red gym shorts and a singlet carrying a mallet.

And she bursts into the corporate meeting, hammer throws the mallet into the screen, which explodes in a fireball, revealing the crawl that says on January 25, Apple introduced the Macintosh. And you'll see why 1984 won't be like 1984.

Now, the point of the ad was not to advertise the product.

It didn't say anything about the product, but to advertise the potential buyership.

It generated common knowledge.

I'm seeing the ad.

I know lots of other companies are seeing the ad.

And what Chwe showed, I mean, it's a story.

How did he prove it?

Well, he looked-- because I mean, that's just a sample of one.

So he looked at other products that only work if enough other people adopt it, products that depend on network effects.

But monster.com was one of the first jobseeking ads.

Now, why would anyone look for a job on monster.com unless they thought that lots of employers were posting there?

Why would employers post there unless they thought a lot of job seekers were looking for jobs there?

Monster.com was introduced at the Super Bowl.

So there are companies that depend on network effects that have to generate common knowledge.

Everyone has to that everyone knows about them.

Another example is the Discover credit card, which was great credit card, rebates, and high limits.

But didn't matter if you were the only one who had a Discover card, because no merchant would accept it.

And no merchant would accept it unless they thought enough people were going to carry it.

Introduced in the Super Bowl.

And Chwe argued that there was another category.

Aside from products that inherently depend on networks, there are prestige goods that depend on other people that you respect also consuming that product.

Products that are consumed in public and where the brand image is important also tend to advertise in the Super Bowl.

And crucially, what Chwe showed was not so much that advertisers were willing to pay per eyeball, but they would be willing to pay a premium for venues that were common knowledge generators, where it was known that a lot of people were to watch them.

They were willing to pay more per eyeball for products that were consumed in public or that depended on network effects.

ADI IGNATIUS: Yeah, so the phenomenon-- maybe the flip side of this phenomenon is the toilet paper shortage during COVID, which was not this, not network effects, but an assumption that I know what you know that I know that you--

STEVEN PINKER: Well, yes, Justin Wolfers speculated that the great COVID toilet paper shortage was like a bank run where people withdraw their money, not necessarily because they think that there's anything wrong with the bank, but they have heard that other people think there might be something wrong, unsound.

And they may just have heard that other people think there might be something that's unsound.

So you get this reverberant doubt.

And no one wants to be the last customer withdrawing at a point where the bank no longer can cover its deposits.

So people rush to the bank to withdraw their savings, which actually causes the bank to fail, which otherwise, it wouldn't.

Likewise, Wolfers suggested that there actually wasn't a toilet paper shortage.

It's true that people were staying home, so they were using six packs of Charmin instead of the big jumbo rolls in their workplace.

But Kimberly-Clark quickly stepped up production to meet the demand.

But somehow, people just know that in an emergency, people hoard toilet paper, which can cause the very shortage that leads people to hoard toilet paper.

And so they did hoard toilet paper.

A lot of retailers then posted signs, max three rolls per customer.

ADI IGNATIUS: That will Reinforce it, yeah.

STEVEN PINKER: And that ended the shortage, not so much because people didn't strip the shelves, because they couldn't.

But they were reassured that since no one else could buy more than three rolls, there was no reason for them to panic.

And again, getting back to common knowledge, how did this originate?

At least according to one history, it all started with another common knowledge generator, The Tonight Show.

Which back in the three network era, Johnny Carson was the King of Late Night.

He had not only a huge audience, but people knew that people were watching Johnny Carson, which is why catchphrases from the show like, "here's Johnny," everyone recognized it.

So one night, I think it was 1973, he said, there have been all kinds of shortages lately.

And there was a meat shortage and a coffee shortage.

And he said, have you heard the latest?

I read it in the papers.

There's a shortage of toilet paper.

Now, it turned out it wasn't true.

At the time, there was no shortage of toilet paper.

But then that created a shortage of toilet paper when everyone ran out to buy it.

And since then, at least according to the story, it's hard to prove, it's just become conventional wisdom that toilet paper becomes scarce in an emergency.

ADI IGNATIUS: Yeah, that is fascinating.

So all of this must be very valuable for people who are in negotiation.

Because negotiation is always, what is it that we both know?

And what is it that only I know?

And I mean, that's how you win.

STEVEN PINKER: Yeah.

ADI IGNATIUS: Yeah, talk about to what extent I know you know.

I mean that's the fundamental of-- and the people negotiate better probably understand this concept.

STEVEN PINKER: Yeah, so negotiation is one of a number of kinds of games in the game theory sense, meaning the my best option depends on what you do and vice versa.

And in any time in which there can be multiple equilibria, cases where everyone is better off if they both do something, but it isn't preordained what they'll do.

So the negotiation is what's sometimes called a battle of the sexes is the technical term.

Has nothing actually to do with the sexes, but it refers to a hypothetical couple, where they like to spend time together.

He would prefer that they go to the hockey game.

She would prefer to go to the opera.

They'd rather go to either than not do something together.

So the question is, which one do they go to?

Both of them are equilibria.

The case of negotiation, let's say a car salesman and a buyer, there's a range of prices in which the salesman makes a profit and the customer pays what they're willing to pay to get the car.

But within that range, the highest the customer is willing to pay, the lowest the seller is willing to sell for, how do they decide?

Obviously, the seller wants it as high as possible.

The buyer wants it as low as possible.

If either of them walks away from the deal, then they're both worse off.

So how do they decide?

So there are many predicaments in life like this where there are many ways of doing something, but both parties are better off if they can figure out some way to do it.

In the case of a negotiation, it's interesting.

This is something pointed out many years ago by the political scientist Thomas Schelling, who won a Nobel Prize for this and other work.

That often, a buyer and seller will-- in order to find somewhere, anywhere to land on that the other guy will agree with, they'll pick something like a splitting the difference or a round number.

He notes that the salesman who announced that his rock bottom price for the car is $30,007.26 is pretty much pleading to be relieved of $7.26.

It's like, oh, come on.

So the why a round number?

I mean, what's so special about a round number?

What's special is other people can think it's special or can expect each other to recognize it as special.

And so these points, focal points, sometimes called Schelling points, points that pop out in the minds of both parties, and that's all they need to come to an agreement, are often where negotiations end up.

ADI IGNATIUS: So when you talk about common knowledge, particularly some of the early references, it seems a different era than where we are now.

I mean, and maybe this was never true, but people my age will look back and say, well, we used to agree on facts.

We probably didn't all together, but we kind of did.

As you say, there were only three networks.

There wasn't this sort of ubiquity of opinion and everything.

Now, we're really in an era where there are competing truths, and I would assume competing common knowledges.

Obviously, there are various common knowledge between people and in relationships, but at a larger level, I guess, my question is, is that eroding the kind of common knowledge that enables social interaction, et cetera, et cetera.

Is that a concern for you?

STEVEN PINKER: There is that fear.

Although, as you say, and I often point out, the best explanation for the good old days is a bad memory.

And there was a lot of polarization in the '60s, too.

It had riots, and terrorist bombings, and assassinations, and so on.

And duly not romanticizing the past, there does seem to be an increase in negative polarization.

That is not just the people disagree, but each thinks that the other is evil.

And它很可能媒体市场的碎片化是其中一个促成因素。

这样一来，不再是每个人都看沃尔特·克朗凯特（Walter Cronkite: 曾是美国哥伦比亚广播公司（CBS）晚间新闻主播，被誉为“美国最受信赖的人”）或亨特利和布林克利（Huntley and Brinkley: 曾是美国全国广播公司（NBC）晚间新闻主播搭档，与克朗凯特齐名），而是首先有了有线新闻，有了福克斯新闻（Fox News: 美国一家保守派新闻频道），其商业模式是培养高度党派化的受众，他们希望听到对一切事物的某种特定解读。

而社交媒体，其发布、转发、推文、转推、链接和重新链接的网络已被证明发生在两个或更多封闭网络内，彼此之间互动不多。

在这些社区中的每一个内部，都可能存在独立的共同信念池，当没有一个公共信号，比如超级碗、约翰尼·卡森或沃尔特·克朗凯特，让每个人都知道每个人都知晓时，这种情况更容易发生。

组织文化与央行沟通中的常识

ADI IGNATIUS: 好的，所以常识这个概念以不同的方式存在于不同形式的关系中，那么在一个公司内部，如果一位高管，一位领导者想要创造一种他或她认为对公司文化有益的常识，是否有一个几乎可以称为“剧本”的东西，来指导如何在这样的环境中创造一种积极的常识？

STEVEN PINKER: 嗯，一般来说，常识是由显眼、公开的事物产生的。

所以面对面会议可以产生常识，而远程会议则不能。

也就是说，当你在一个房间里时，你看到其他人。

他们看到你。

你知道他们彼此看到对方，也看到演讲者或领导者。

所以我认为仍然存在——这也是原因之一——就像超级碗一样，它是一个广播版本，但公开显眼的通知扮演着重要角色。

有时，回到整个经济体，美联储（Fed: 即美国联邦储备系统，美国的中央银行）的声明之所以被像拉比（Rabbis: 犹太教的宗教领袖和学者）解读**《塔木德》**（Talmud: 犹太教的口传律法和经文汇编）一样仔细审查和研究，是因为美联储主席所说的任何话语，当人们知道其他人也听到了，并会根据对其他人行为的预期而行动时，就能创造出自己的现实，这反过来又会自我强化，制造泡沫或衰退。

所以我引用了艾伦·格林斯潘（Alan Greenspan）的话，他曾说过：“自从我担任美联储主席以来，我学会了含糊其辞，语无伦次。

如果我对你来说显得清晰，那你一定误解了我的意思。”

因为一个信号，比如说，经济衰退即将来临，就会制造出那场衰退，因为公司会因为害怕不得不裁员而停止招聘。

消费者会因为害怕失业而停止购买，这两者都会创造出彼此的现实。

所以美联储主席必须非常非常小心她或他所说的话。

常识与威权主义：从中国到罗马尼亚

ADI IGNATIUS: 是的，所有这些有趣之处在于，您在某种程度上谈到了政治，谈到了威权主义政治。

我曾在中国生活。

我也曾在俄罗斯生活。

您确实描述了那种现象，即每个人都知道政权腐败，但没有人说出来，因为你无法确定如果你走上街头，是否会有其他人与你同行，尽管每个人都或多或少知道。

然后你就会明白为什么威权主义，为什么你必须控制一切。

因为一旦你放松任何控制，它就会为沟通和理解创造可能性。

这就像罗马尼亚的齐奥塞斯库（Nicolae Ceaușescu: 罗马尼亚前共产党领导人，其政权在1989年被推翻）垮台的那一刻。

他控制了一切。

突然，在他发表演讲时，后面有几个人在喊叫。

发生了一些事情，他意识到一切都结束了。

因为要么是完全控制，要么是完全失控。

STEVEN PINKER: 特别是，控制必须是——没有哪个独裁者能控制住每一个国民。

没有足够的火力，也没有足够的告密者。

正如我在同名电影中引用甘地（Mahatma Gandhi）的角色所说，他曾对一位英国殖民军官说：“最终，你们会离开，因为如果印度人拒绝合作，十万英国人根本无法控制三亿五千万印度人。”

他本可以说，拒绝协调或无法协调。

所以，如果人们同时站起来，如果他们都冲进宫殿，如果他们都停止工作，他们就能推翻一个政权。

但如果每个人都害怕自己是唯一一个，他们怎么能做到呢？

如果他站起来，他可能会被抓走或送进监狱。

如果每个人同时抗议，那么他们就可以——人多势众是安全的。

但协调中也有安全。

所以必须有一种方法来生成常识：“现在是我们大家一起站起来的时候了。”

所以，在公共广场上的抗议，每个人都看到其他人看到其他人，通常就能做到这一点。

这就是为什么独裁者经常害怕公共抗议。

或者如果有广泛流传的杂志、电视节目、广播节目，这就是他们打压媒体的原因。

ADI IGNATIUS: 谈谈白纸。

STEVEN PINKER: 哦，是的。

有一个来自苏联的笑话，说一个人在红场（Red Square: 位于俄罗斯莫斯科市中心的著名广场）散发传单。

当然，克格勃（KGB: 苏联的国家安全委员会，是苏联主要的秘密警察和情报机构）逮捕了他。

他们把他带到警察局总部，结果发现传单都是白纸。

他们质问他。

他们要求：“这是什么意思？”

他说：“有什么好说的呢？”

“这太明显了。”

这个笑话的重点是他在生成常识。

他不需要说什么，因为人们已经知道了，但他们不知道其他人也知道。

所有接受传单的人都在生成“每个人都知道每个人都知道”的常识，这就是它如此具有颠覆性的原因。

在生活模仿笑话的案例中，普京的警察逮捕了一些携带白纸标语的人。

ADI IGNATIUS: 嗯，我不知道是不是在那之前——在中国，公开抗议和公开异议是非常危险的，在COVID应对不当之后，曾发生过著名的白纸抗议。

STEVEN PINKER: 哦，有意思。

ADI IGNATIUS: 可能是受到最初的——

STEVEN PINKER: 笑话的启发。

ADI IGNATIUS: 苏联笑话，是的。

常识的普遍性及其影响

ADI IGNATIUS: 所以这本书很迷人。

您准确地指出了常识，以及我们如何知道我们所知道的，我们如何思考某些事情以及我们如何运作。

我们应该如何利用这一切呢？

STEVEN PINKER: 嗯，这个问题很难回答，因为我写这本书并不是一本操作指南、手册或自助书籍。

它更像是一部基础科学、逻辑学和哲学著作，具有大量的应用。

在特定情况下如何解决问题，通常取决于具体的收益。

如果你未能协调会发生什么？

如果你协调成功会获得什么？

如果存在多种协调方式，谁受益，谁受损？

所以没有单一的公式。

但它是一个观察世界的透镜，仅仅因为协调在人类事务中无处不在。

任何公司、任何机构、任何学校、任何关系、任何伴侣、任何友谊、任何家庭，这些都是人们试图协调的例子。

他们总是必须通过某种常识信号进行协调。

他们常常为了维护关系，不得不将某些事情排除在常识之外。

因此，所有礼貌、委婉语（Euphemism: 避免直接说出令人不快或禁忌的词语，而使用更温和或间接的表达）、影射（Innuendo: 暗示或含蓄的评论，通常带有贬义）、机智（Tact: 在处理人际关系时，避免冒犯或伤害他人的敏感性）、假装没看到“房间里的大象”、拐弯抹角、虚伪（Hypocrisy: 言行不一，假装拥有某种道德或信仰）、文雅的虚伪（Genteel Hypocrisy: 指一种表面上礼貌得体，实则掩盖真实意图或不诚实的虚伪行为）等现象，我都认为是人们私下知道某事，但有某种原因要将其排除在常识之外的情况。

原因是，常识中的某些东西会改变关系。

有时，你不想改变关系。

或者你不想发出错误的关系信号。

所以举几个例子，我的意思是，系统性虚伪最常见的例子就是礼貌。

“如果你能把盐递过来，那就太棒了。”

什么？

如果你从字面上理解，这真的没有多大意义。

但你能把盐递过来吗？

你觉得你可能会把盐递过来吗？

我们为什么要经历这些仪式？

那是因为我们不想互相指手画脚。

我不想像对待管家一样给你下命令，无论是假设我们是朋友，还是陌生人。

ADI IGNATIUS: 这真的很有趣。

所以良性的虚伪或其中一些规矩，它们可能不直接，可能不诚实，但它们是我们运作所必需的。

STEVEN PINKER: 它们是我们维护关系所必需的，因为我们的关系是依赖于常识的协调博弈。

有时，我们不想破坏一段关系，所以我们避免了常识。

ADI IGNATIUS: 史蒂芬·平克，感谢您参加IdeaCast节目。

STEVEN PINKER: 谢谢您的邀请。