323 - Common Knowledge - Steven Pinker

Summary

You Are Not So Smart – Episode 323 Summary
Guest: Steven Pinker
Topic: Common Knowledge
Date: September 29, 2025

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Brief Overview

In this episode, host David McRaney interviews renowned cognitive psychologist Steven Pinker on the concept of "common knowledge," the subject of Pinker’s latest book, When Everyone Knows that Everyone Knows: Common Knowledge and the Mysteries of Money, Power, and Everyday Life. The discussion explores how shared, recursive awareness shapes coordination, language, social norms, institutions, and even political resistance. Pinker provides accessible explanations and thought-provoking examples, from driving conventions to how language evolves—and why authoritarian regimes are obsessed with suppressing public awareness.

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Key Discussion Points & Insights

What Is Common Knowledge?

• Defining the Term ([15:09-17:19], [18:06-21:51])

  • Common knowledge is "the state in which 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." (Steven Pinker, 15:09)
  • Humans don’t literally process infinite recursions; public, conspicuous, or self-evident events stand in for this infinite nesting, allowing us to behave as though we’ve checked those cognitive boxes.
  • "When something is conspicuous, when it is self evident, when it is public, when it is out there, that grants us common knowledge." (Pinker, 15:09)
  • This shared recursive awareness is necessary for coordination—from simple meetings to massive social undertakings.

• Contrast with Similar Terms ([04:48-06:29])

  • Private knowledge: What only one person knows.
  • Shared knowledge: Where some, but not all, are “in the know.”
  • Common knowledge: When “just about everyone” knows, and knows that everyone knows (and so on), enabling societal-level alignment.

The Power of Common Knowledge in Daily Life

• Coordination & Social Conventions ([06:29-09:30], [18:06-21:51])
  • Drives, rituals, norms (traffic laws, weddings, money) function because they’re coordinated on the back of common knowledge.
  • “There is no reason to drive on the right, except there’s a very good reason to drive on the same side that everyone drives on, whichever side that happens to be.” (Pinker, 02:05, reinforced at 21:16)
  • Language works similarly—words maintain meaning through a shared, recursive expectation across speakers.

How Language Evolves: From Common Knowledge to Contention

• Changing Meanings ([21:51-27:54])

  • Dictionaries and usage are followers of how language actually operates; there’s “no authority for what a word means other than the way people use it.” (Pinker, 24:39)
  • Prescriptive advice (e.g., “hopefully,” “nauseous,” “assets”) can lag behind living language, which shifts organically through evolving common knowledge in subcultures or professions.
  • Pinker gives the example of "assets" acquiring a new meaning in media/publisher circles.

• Prototype Theory and the Fuzziness of Definitions ([28:00-34:52])

  • Not all categories have sharp boundaries; we often use prototypes—e.g. the “birdiest bird”—rather than strict definitions.
  • For coordination (in law, medicine), fuzzy everyday categories sometimes must be crisped up through public conventions ("pieces of paper," ceremonies).

The Fallacy of Reification and the Social Reality of Concepts

• Debate with Stephen Jay Gould ([34:52-41:02])

  • Pinker strongly disagrees with Gould's claim that “general intelligence” (g) is a fallacious abstraction.
  • “There has to be some explanation as to why [different types of intelligence] intercorrelate. It is not a fallacy of reification to ask why they intercorrelate.” (Pinker, 37:41)
  • Abstract concepts like "the economy," "money," or "laws" exist as social realities—held up by common knowledge, not physical substance, making them no less real.

• Response to Yuval Noah Harari ([41:02-43:49])

  • Disagrees with Harari’s framing of social realities as “fictions”; prefers to see them as conventions propped up by common knowledge. “It doesn’t literally mean they’re fictions... they exist as common knowledge.”

The Social Dynamics of Relationships, Face, and Politeness

• Common Knowledge and Transitions ([44:50-49:54])
  • Social roles—friendships, loves, authorities—depend on recursive, mutual awareness.
  • Transitions (becoming lovers, changing status) require careful navigation, often through indirect language, tact, politeness, innuendo, and euphemism.
  • Example: Politeness (“Could you pass the salt?”) softens authority implications and preserves the relationship by allowing an “out.”

Authoritarianism, Information, and Coordination

• Suppressing Common Knowledge ([49:54-52:40])

  • Authoritarian regimes fear not dissent in itself, but public, coordinated dissent. They act to prevent common knowledge of opposition (by censoring, banning assembly, etc).
  • "Despotic regimes don't actually care about dissent. They care about common knowledge of dissent." (Pinker, 50:24)
  • Democracies enshrine freedom of assembly and speech precisely to allow coordination and challenge to power.

• Pluralistic Ignorance ([52:40-53:59])

  • When everyone believes others hold a belief (e.g., hazing is cool), but nobody actually does.
  • Enforced by both mutual misunderstanding and sometimes by punishment.
  • Online, this phenomenon can be aggravated by bots and separated information ecosystems.

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Notable Quotes and Memorable Moments

• “When something is conspicuous, when it is self evident, when it is public, when it is out there, that grants us common knowledge.”
  — Steven Pinker (15:09)

• “Despotic regimes don't actually care about dissent. They care about common knowledge of dissent... If all the population is disgruntled, but none can act on it in cahoots at the same time, they can control everyone.”
  — Steven Pinker (50:24)

• “There is no authority for what a word means other than the way people use it. The lunatics are running the asylum.”
  — Steven Pinker (24:39)

• “All of our conventions, that is, arbitrary ways of doing things that work, if everyone does them the same way, depend on common knowledge, which can be conveyed tacitly.”
  — Steven Pinker (21:20)

• “Authoritarian regimes are terrified of public protests. Conversely, democracies enshrine freedom of assembly as a fundamental right. All of these are mechanisms of regimes preventing common knowledge.”
  — Steven Pinker (51:30)

• “I argue that that's why we have tact, politeness, innuendo, euphemism, hints, genteel hypocrisy, all cases in which we don't want to explode a relationship that's in force, but we have to do something that contradicts them.”
  — Steven Pinker (46:22)

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Timestamps for Important Segments

• [02:05] – Pinker on driving conventions and the essence of coordination
• [14:33-17:19] – Introduction and technical definition of common knowledge
• [18:06-21:51] – How common knowledge works in real life and examples (marriage, language, etc.)
• [21:51-27:54] – Language change, prescriptive vs. descriptive grammar, and evolving common knowledge
• [28:00-34:52] – Prototype categories and the need for conventions in law/science
• [34:52-41:02] – The “reification” of concepts, debate with Gould, and the social reality of abstractions
• [44:50-49:54] – Politeness, face, social rituals, and indirect language as tools for managing common knowledge
• [49:54-52:40] – Common knowledge in authoritarian and democratic regimes
• [52:40-53:59] – Pluralistic ignorance and modern information ecosystems
• [54:09] – Pinker’s hopes for the book’s impact and intended audience

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Tone and Style

The episode is intellectually curious, witty, and friendly. McRaney’s enthusiasm for linguistics and Pinker’s clarity make complex ideas accessible and often amusing. Their exchanges are lively, including some nerdy tangents, but always return to real-world implications.

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Who Should Listen (or Read the Book)?

As Pinker puts it: “Anyone who's just interested in what makes us tick in social life and the various puzzles, mysteries, fads, crashes, bubbles, rituals, hypocrisies, just human social life on scales from couples to societies.”
— [54:09]

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This episode is a must for anyone fascinated by psychology, linguistics, group dynamics, power, politics, or simply the mechanics of why society works (or doesn’t). Pinker’s new book, according to this discussion, is packed with vivid examples, humor, and sharp insights into both mundane and high-stakes aspects of human life.

Transcript

[Jeff Bridges]

Morning, Zoe. Got donuts.

[Dana]

Jeff Bridges, why are you still living above our garage?

[Jeff Bridges]

Well, I dig the mattress and I want to be in a T mobile commercial like you teach me. So Dana.

[Dana]

Oh no, I'm not really prepared. I couldn't possibly at T Mobile get the new iPhone 17 Pro on them. It's designed to be the most powerful iPhone yet and has the ultimate pro camera system.

[Jeff Bridges]

Wow, impressive. Let me try. T mobile is the best place to get iPhone 17 Pro because they've got the best network.

[David McRaney]

Nice.

[Dana]

Je free.

[David McRaney]

You heard them.

[McDonald's Announcer]

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[Jeff Bridges]

So what are we having for lunch?

[Dana]

Dude, my work here is done.

[T-Mobile Announcer]

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[Sponsor Representative]

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[David McRaney]

If you want to know more about what I'm talking about, check it out.

[Sponsor Representative]

Middle of the show.

[Steven Pinker]

Feel happy.

[McDonald's Announcer]

They went quiet. They went quiet.

[Podcast Host (David McRaney)]

Welcome to the you are not so Smart podcast.

[David McRaney]

Episode 323.

[Steven Pinker]

Why do we drive on the right and not on the left? Well, there is no reason to drive on the right, except there's a very good reason to drive on the same side that everyone drives on whichever side that happens to be.

[Podcast Host (David McRaney)]

Welcome to the you are not so smart podcast. My name is David McGraney and the person you just heard is Harvard psychologist Steven Pinker. And what you just heard him talking about is something psychologists refer to as common knowledge. Before we get started, I should note my audio may sound a bit different at the moment because I'm recording this from Ernest Hemingway's house in Idaho. Yes, Ernest Hemingway's house. And yes, it's in Idaho. I received an invitation to be the writer in residence here from the nice people at the community library, an institution here in Ketchum, Idaho, who curates the home and does all sorts of nice book related things. I said yes to that invitation. And here I sit in Ernest Hemingway's house. You can see the house and all the other stuff they do there at C O M L I b dot org. That's comlib dot org okay, back to the show. First of all, common knowledge isn't the same thing as common sense. Common knowledge is an alignment of mental states, the recursive awareness of shared awareness, which serves as the invisible infrastructure of human social interaction and coordination. That's a lot. I know. We will get into all of what that means in just a second, but it's important to note that common sense is something else. It's a sort of folk term for widely shared assumptions about how you ought to do things, how you ought to behave. But those assumptions are held privately by each individual, and until tested, until people speak these assumptions aloud and share them publicly, they remain unverified through mutual awareness. And Steven Pinker is about to tell us all about this on this episode because he has written a book about all of this titled When Everyone Knows that Everyone Knows Common Knowledge and the Mysteries of Money, Power, and Everyday Life. Before we get into that interview, please allow me to set the stage by sharing with you some knowledge. That way it becomes something that I know that you know, and then we can both know that we both know those things.

[David McRaney]

So first, in general, there are three.

[Podcast Host (David McRaney)]

Kinds of knowledge Pinker writes about in his book. There's private knowledge, which is something you know but other people do not know. For instance, you may be incredibly anxious before a meeting, but until you share that this is private knowledge. Then there's shared knowledge, which is something two or more people know. But not everyone you know or don't know knows this. For instance, you and three of your friends might be walking into a restaurant to meet some people, and you get caught in some unexpected rain. You in that small group all know it is raining, but until you enter the restaurant, your friends inside who have been waiting on you don't know something that you and your friends know. And common knowledge is something that just about everyone in a large group, like an entire society or institution, knows. And those people in that large group or institution know that everyone else in that large group or institution knows that thing. For instance, when your country elects a new leader within a few days, everyone knows who that person is. And everyone knows that pretty much everyone else knows that, too. Pinker argues in his new book that common knowledge, also called mutual knowledge, is the fundamental aspect of cognition that enables coordination. And coordination is the fundamental aspect of human behavior that allows the members of a social unit, be it a party or a family or a group of friends or a company or an entire country to cooperate and act collectively. For instance, while driving, when you see a red light, you stop. And when you see a green light, you go. Most of the time, if everyone who is driving shares this common knowledge, and we are all confident that everyone knows that everyone else knows that everyone else knows, we can use that common knowledge to coordinate an extremely complex and potentially dangerous set of behaviors in order to extract a lot of benefits from automobiles and freeways and cities and so on. But that's just the beginning. Common knowledge is the foundation of all sorts of systems that require coordination. Things like markets and governments and contracts and rituals and gossip and norms and taboos and friendships and romantic interactions and jokes and education and language itself. When you see through this lens, society begins to look a lot like a multiplayer coordination game. In fact, game theory, as Thomas Schilling once put it, is the currency of norms, rituals, and institutions because those things act as focal points. That's the language used in game theory. Focal points are signals everyone recognizes to help them align their behavior with the benefit of not having to re agree or discuss it out loud or write it on paper every time we interact. And those focal points underpin just about everything that requires us to all agree on something that in the end only works because we all agree on it. For instance, money. Like physical paper money. Yeah, it's just a piece of paper, and stacks of money are just stacks of paper. And numbers in a bank account are just numbers. But if we all agree on what that paper represents and what those numbers represent, then things like billionaires can exist. Social classes based on income can exist. Taxes and corporations and whole economies will exert enormous, lifelong influence over our thoughts, feelings, behaviors, and physical well being, all based on the mutual knowledge of a shared agreement. And as Pinker argues, that means a great deal of our shared experience of reality itself depends less on the truth than it does on the predictability of shared agreements and our shared understanding of those agreements. The book gets into all sorts of stuff like this, especially game theory. Things like the prisoner's dilemma and how social life is, in the end, a web of games where common knowledge offers what scientists call stable equilibria. That's when a social pattern, rule, or custom just keeps reproducing itself. And it does that because it works well enough for everyone involved, and it works well enough because everyone expects everyone else to keep engaging in that pattern, following that rule and adhering to that custom. And that's what this interview is all about. But also, please allow me to apologize ahead of time for how this interview goes on a tangent or two about how all this applies to language and meaning. That's because I'm writing a book about all that, and since Pinker is an expert in that domain, I couldn't help myself from asking him about that kind of stuff. Also, we get into how authoritarian governments and regimes that oppress people depend on suppressing common knowledge and influencing people's behavior through that suppression. And all in this interview. And the interview will happen right after this break.

[Jeff Bridges]

Morning, Zoe. Got donuts?

[Dana]

Jeff Bridges why are you still living above our garage?

[Jeff Bridges]

Well, I dig the mattress and I want to be in a T mobile commercial like you teach me.

[Dana]

So Dana oh no, I'm not really prepared. I couldn't possibly at T Mobile get the new iPhone 17 Pro on them. It's designed to be the most powerful iPhone yet and has the ultimate pro camera system.

[Jeff Bridges]

Wow, impressive. Let me try. T Mobile is the best place to get iPhone 17 Pro because they've got the best network.

[David McRaney]

Nice.

[Dana]

Jeffrey, you heard them.

[McDonald's Announcer]

T Mobile is the best place to get the new iPhone 17 Pro on us with eligible traded in any condition.

[Jeff Bridges]

So what are we having for lunch?

[Dana]

Dude, my work here is done.

[T-Mobile Announcer]

The 24 month bill credit is on Experience beyond for well qualified customers plus tax and $35 device connection charge credits ended balance due if you pay off earlier. Cancel Finance agreement. IPhone 17 Pro 256 gigs $1099.99 a new line minimum $100 plus a month plan with auto pay plus taxes and fees required. Best mobile network in the US based on analysis by Ooklab speed test intelligence data 1H 2025 visit t mobile.com your.

[McDonald's Announcer]

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[Steven Pinker]

Prices and participation may vary.

[Sponsor Representative]

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[David McRaney]

So if you're the kind of person.

[Sponsor Representative]

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[David McRaney]

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[Sponsor Representative]

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[Podcast Host (David McRaney)]

And now we return to our program.

[Steven Pinker]

My name is Steven Pinker. I am a cognitive psychologist and a professor of psychology at Harvard University. I've taught at MIT and Stanford in the past, but have been at Harvard for quite some time now.

[David McRaney]

This is a book about common knowledge and this, I feel like, is one of those things that ironically and meta ironically people are like, yeah, I know what that is, and I know that you know that I know what that is. But scientifically speaking, just to clear the room and lay a foundation, what is scientifically speaking, common knowledge in the technical sense.

[Steven Pinker]

Common knowledge refers to the state in which 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, which sounds impossible because your head starts to spin with two or three layers of I know that she knows that I know that she knows, let alone an infinite number, which is technically what common knowledge comprises. But the reason, and of course I'm a psychologist, so I care about how this logical state actually is processed by mortal humans thinking thoughts. And you know, we, we do think about what other people think about what, what, what we think it's the basis for, you know, a lot of mysteries, a lot of comedies of manners, of mistaken identity. But we don't have to actually go through the layers on layers of embedded thoughts within thoughts within thoughts within thoughts. Because when something is conspicuous, when it is self evident, when it is public, when it is out there, that grants us common knowledge. At a stroke, if something happens, a cup falls off a table, I'm seeing it, I'm seeing you see it, you're seeing me see it. It's all we need to do, know that the other knows, that we know. I've actually done studies that bear this out, that if you ask people ridiculous things like is it true that she knows that he knows, that she knows that he knows that she knows that she, that he knows, and we know they couldn't possibly literally understand it, but if it is something that is public and conspicuous, they'll say, yeah, she, he must, she must. So you get, we have a sense that the common knowledge exists when something is self evident. And that's why it can play a role in human affairs that you don't have to have an infinite number of thoughts. And the reason that it's significant is that it's necessary for coordination for two people to be on the same page, to follow the same conventions, the same norms, obey the same rules, be in the same organization. There are a lot of ways of doing things that you do for no other reason, that you know that the other person is going to do it that way, and they know you're going to do it that way, and everyone wins.

[David McRaney]

I love that. Like, it's very difficult to just define it in one or two words, but that, but once you get the ad infinitum thing going, it starts to make more sense. Even though that should be the point where it starts to make the least amount of sense. I know I'm jumping straight into like sort of like super nerd Dom here, but I can't get over the fact that common knowledge, to accept it, to like, to have that intuitive like burst is to sort of acknowledge that you're in an infinite recursion moment and then just bypass it and be okay with it.

[Sponsor Representative]

What do you make of the.

[David McRaney]

That aspect of cognition where a person. I know that you know that I know that you know that I. But I don't actually engage in that. I just sort of have a nice pop into awareness of it.

[Steven Pinker]

Yeah, I think, I mean it, it results a certain paradox, namely that logically speaking, the nothing short of common knowledge can guarantee that two people will be on the same page and do something that they both want to do, as long as they both do it. So something as simple as a rendezvous. If we are getting together for coffee and we don't have a way of generating common knowledge, say one of our cell phones has gone dead, it's not enough for me to know that you like to go to Starbucks, because you might know that I like to go to Pete's, so you might go to Pete's instead. And I can, and I anticipate that. And I think, oh gee, well, he knows I like to go to Pete's, so he's going to be considerate and go to Pete's. But then you're going to think, oh well, Steve is considerate, he knows I like Starbucks, so Steve's going to go to Starbucks. I said, oh, no. But Steve is going to say, know that I know that he likes to go to Pete's, so he's going to go to Pete's after nothing. All of those layers don't suffice compared to knowing that each one knows what the other one is planning to do. Now, if that is true, if everything that we do together, and we as humans do lots of things together, we form armies and universities and governments and companies and social clubs and groups and soccer teams and so on, all of which require coordination, people being on the same page doing something at the same time that someone else is doing something, and it results in something that we want, how do we do it if it requires this superhuman cognition? And the answer is that because we can get a sense that common knowledge is in force by something being public, conspicuous, you can't miss it. That's what allows us to Coordinate. And that's why so much of human interaction is guided by arbitrary public signals and ceremonies. People get married in a circumstance in which everyone sees the couple, everyone sees everyone else seeing everyone else see the couple. And that's what marks the transition. That everyone respects that they are no longer available, that they are both jointly responsible for children. All of those rights and obligations are marked by this public ceremony which generates common knowledge. Why do we have arbitrary things like a seven day week day of rest on Sunday or Saturday? Why do different subcultures mark themselves off by certain hairstyles or tattoos or mutilating various parts of their body? It generates a signal that everyone knows you're part of that same community of coordinators. Why do we drive on the right and not on the left? Well, there is no reason to drive on the right, except there's a very good reason to drive on the same side that everyone drives on, whichever side that happens to be. And getting back to getting to language, which I know is a common interest of ours, words work because they're common knowledge. That is when I learn a word, when a child learns a new word, they don't have to then test it out on everyone else that they subsequently meet. If mom uses it or if you're older brother uses it, then kids tacitly assume it's common knowledge. Everyone else will know what I mean by it and they amongst themselves will use the word. All of our conventions, that is arbitrary ways of doing things that work, if everyone does them the same way, depend on common knowledge, which can be conveyed tacitly. It doesn't have. It can be, but doesn't have to involve the thinking through of the layers of thoughts within thoughts within thoughts.

[David McRaney]

You've written before. Many of your peers and other scientists who think about this sort of stuff all the time agree that the purpose of language evolved or as a tool or whatever for coordination, for coordination of behavior between these supposedly sentient human entities who all share language. And you write in your book about how you use the salt and pepper example, which I love, in that we have to first all agree that this word means that. But it's not just an agreement, it's. I know that you know that, I know that you know that. We think that this is the sound that references this. When I think about that, I imagine that as you know, not all, many of our terms for things evolve over time and they mutate over time and there's a sort of a leading wave in which not everyone is quite on board with what this word means.

[Sponsor Representative]

Anymore as it changes.

[David McRaney]

And I wonder if you have any thoughts on that, because I see that coming up a lot right now. There, there are words that maybe scientists have come to an agreement on something, or in legal terms, there's a. An agreement that this word means this or this term means that, but the. It's not evenly distributed across the population. I'm wondering about your thoughts on this and how we tend to, like, wrestle with that when it becomes a problem.

[Steven Pinker]

Yeah, it's something I dealt with in greater detail in a previous book, the Sense of Style, my style manual, where I dealt questions of prescriptive language usage. That is when the experts, the copy editors, the language mavens tell us, no, you've been using a word wrong or you can't use it that way. You can't use hopefully to mean it is to be hoped that hopefully the rain will stop soon. Allegedly, that's an error. Hopefully it doesn't mean that. What does it mean to say that? It doesn't mean that? If everyone uses it in a particular way, that's what it means. That is that language is a convention. It is a matter of common knowledge. You use it because you know other people will use it that way, because they in turn expect that you and everyone else will use it that way. And that can change over time. That's why language changes. And so some of the advice like that, prescriptive grammar experts, the people who just tell you, you know, sticklers, you can't say 10 items or less. You have to say 10 items or fewer. But they kind of miss the boat because since no one decides what words mean, they are matters of common knowledge. They mean what everyone expects everyone else expects them to mean. Sometimes grammar advice can get in the way of clarity. Hopefully being an example. The prescriptive rule is that hopefully can only mean in a hopeful manner. So you can say, you know, hopefully he asked her out on a date, meaning he hopes that she'll accept that's not the way people use the word anymore, and they haven't for 100 years. And there are lots and lots of adverbs that behave that way candidly. Can either mean he did it in a candid manner, or I am sharing something with you candidly. There are called sentence adverbs or verb adverbs or usages, I should say, because they're the same words and we often go back and forth and it can be downright misleading. Sometimes the advice is what is correct, such as the word nauseous. This is an example of a word whose meaning has pretty much changed. But there are sticklers who will say that nauseous does not mean nauseated, it means nauseating. So I can say he's really nauseous, meaning, not that he's about to barf, but he's about to make me barf. Now that's the so called rule. But if you obey it, no one's going to know what you're talking about. You're going to confuse people. And I speak here with some authority because not only did I write the Sense of Style, about grammar and usage and style and clarity and grace, but I was the chair of the usage panel of the American Heritage Dictionary when that was an ongoing concern. And when I joined the board, I asked the editor in chief, the guy who actually decides what goes in the. The dictionary said, how do you guys decide what goes in the dictionary says, well, we listen to the way people use words. That is, there's no one in charge, the lunatics are running the asylum. That there is no authority for what a word means other than the way people use it. When you're in the midst of an ongoing change, you can think that the language is deteriorating because younger people or the hoi pollo are using a word in a way that by your understanding is incorrect. But it just. But since no one actually legislates the meaning of words, the common knowledge can change. It changes organically. There's, you know, very little you can do to stop it. And, and it happens often, starting with some subculture and sometimes not necessarily spreading out to the community of English users as a whole. And as you noted that sometimes it happens with scientific jargon, but it can also happen in other specialties. So I was baffled for a while when my last book came out, when the publicist at Penguin Random House kept talking about assets. Well, do you have the assets? And you know at some point we're going to share the assets with you. Andre bank said, you know, politely, what the hell is an asset? So it turns out that an asset in the ME world of social media mavens and, and, and consultants is like a, a graphic that you can post in a tweet. A post, it could be your banner and your homepage. But an asset is kind of something that a graphic designer puts together for you. It's not the way the asset is typically used, but somehow it caught on it within that community of social media consultants. It has been spreading. I don't know if you've heard it used in that setting.

[David McRaney]

Oh yeah, I've been asked for My to deliver assets many times.

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[David McRaney]

This makes me wonder, like the. There's a like one of the oldest philosophical dorm room bong hit conversation. And also in the, you know, the agora conversation, like there's a trying to get at what is the essence of X? Two oranges plus two oranges equals four oranges. Take away the oranges and you have two plus two equals four. And that's how this language is nice. Can be nice and abstract. And this language has referent things to refer to that we can all agree. I'm discussing that object, the orange. But then we need to try to like define it and settle on a definition. And I can't think of anybody better to ask this. And this repeats in prototype theory and cognitive linguistics that there is no actual essence. They use bird as their. They love to say. They ask the question, what is more a bird, an ostrich or an eagle? And then you go through all of that research where people intuitively answer like, well, I would say an eagle. And then you say, well, why is that? And then they really start having this moment of I don't actually know why I think that or feel that. And then you can ask this beautiful follow up, which is what is the most bird bird. Like what is the birdiest bird of all Birdness. And depending on the culture, people or era, people will say sparrow or robin or stuff like that. Then you can say like, why? And you so really used to having this interesting introspection. I'm wondering, when we talk, we're talking about coordination, which your book focuses on a great deal when it comes to language. For the sake of coordination, what typically happens here and what do you expect will happen in like trying to settle a definition that we can work with going forward that will impact people's lives in legal terms, medical terms, and so on?

[Steven Pinker]

Yeah, so these are. And you're talking about a line of thinking that goes back mainly to Wittgenstein and then revived within cognitive psychology by Eleanor Rosch starting in the 1970s, of whether the meanings of words and human concepts in general can be specified by definitions necessary and sufficient conditions. This is an idea often attributed to Aristotle. Or whether they are more fuzzy sets, co occurrences of properties that tend to go together. And we have a stereotype, we have a prototype, but they're unclear cases as well. The answer is probably that we, at least cognitively, we can go back and forth. We can have two different modes of thinking of something, as when you talked about the fact that people often agree in their judgments of Typicality that a sparrow is a better example of bird than a penguin or an ostrich. And you know, that's a very robust intuition. And if you open the dictionary and you look up bird and you have to have a little picture, they're not going to show an ostrich, they're going to show, you know, kind of Joe bird, you know, probably a sparrow. But it may not even exist. It may be a composite of all the properties that birds have in common corresponding to the first image that comes to mind when you think of birds. But people can all don't have to think that way. So you could ask people, what's a better example of an odd number? 7 or 246,827. Now people will say the first one's a much better example because the second one has all these even digits in it. But on the other hand, something's either an even number or that is not a fuzzy concept. And the same people who will say that 7 is a better odd number, whatever that means, will also say, well, yeah, but of course 246,847 really is a perfectly good odd number too. It just, it doesn't feel as odd e or odd ish. And you can go back and forth. And we have to go back and forth because of the coordination problem. Namely we often, even though we can all have different intuitions as to where the boundaries are, especially when they're gray areas, sometimes we got to make a decision, we just have to agree. And for that reason, among others, we settle on conventions. The conventions are common knowledge and they allow us to coordinate an example. When are two people in a committed relationship, they get closer and closer. They date fewer and fewer other people, but then they get married and that is a couple. So we socially, we often have conventions that are crisp, hard, well defined, often advertised by common knowledge generators like ceremonies or pieces of paper. That is conspicuous, self evident things that everyone can agree that everyone else can agree on while retaining the background knowledge that there are underlying continua. But also sometimes in science, what start out as fuzzy family resemblance categories can gain a precise hard and fast definition as scientists uncover. Scientists don't use the word essence, but in many cases there is an essence. So you know, what is water to a scientist? Water is H2O and that's all there is to it in everyday parlance. There are things that can be that we say our water or aren't water that don't depend on them being H2O. This is a lovely study by Barbara Malt, a former student of mine, that we would say, for example, that tea is not water. But if we had polluted water that had as many suspended solids as tea, we would say that it is water. So it's not even a matter of chemistry in everyday parlance. But then when we shift and we put on our scientist hat, we say water is H2O. And of course, as you note, the most contentious example of that playing out in everyday life, there are a lot of them. When I teach the section of my course on fuzzy family resemblance categories versus strict all or none categories, I trot out a list of examples. What's a car? Many years ago, SUVs were classified as trucks, not cars. Even though they have really become cars, they're the most popular everyday personal vehicles because they were classified as trucks. That is, they were given a hard, crisp definition. They fell under much laxer standards for fuel economy, which is why it was in the interests of car companies to make lots and lots of SUVs because they could do it without calling them trucks meant that they didn't have to follow the fuel efficiency guidelines that apply to cars.

[David McRaney]

I love how all of this comes back to coordination. And I pushed back against this. I did not want language be about coordination. I wanted language to be about articulating the ineffable and expressing things that are impossible to express and equals MC square. I wanted those languages to be examples of. Do you see the power of language? And then let me ask you one last thing about this before I ask you about coordinations. Very specifically, as much of a nerd as I thought I was about all this, I ran across Stephen Jay Gould's fallacy of reification. And I can't get it out of my head, which is I was. I'm talking about it in the thing I'm writing about how genius was a very. We were all very okay across several cultures that shared the word once it was sort of returned to us from the. From the original Latin. And of course, like the Romans had the. For them it was a deity type thing. Then all the. Somewhere in the Enlightenment we. It got returned to the language and given a new meaning. And for. For several hundred years it was just this abstraction. It was just an abstraction and we accepted it as such. And then once we got psychometrics, it got promoted to a concrete. And the. Supposedly, the way the fallacy of revocation works is sometimes when that happens, it happens when it ought not have happened or it happens earlier than it should have happened. It's a. It got promoted when it didn't deserve to be promoted. And that can lead to all sorts of problems where genius was an abstraction and then it became a concrete term that you could measure and rank. And that led to all sorts of issues, including by some accounts maybe even the testing that would lead to justifying eugenics and stuff like that.

[Steven Pinker]

Yeah, I have a very. By the way, I have a totally different. I completely disagree with.

[David McRaney]

That's why I'm asking you. I want to know exactly what you think about this, please.

[Steven Pinker]

I think Gould got it really wrong. Gould.

[David McRaney]

Okay, I'm here.

[Steven Pinker]

Gould was a brilliant, brilliant writer and I learned a lot of biology from reading his essays in natural history. He was an inspiration to me in writing for a larger audience and I had a very good relationship with him. He tragically died of cancer at the age of 60. Gould used his formidable intelligence to try to undermine the idea that there's any such thing as intelligence. Quite hypocritically because any academic spends a lot of time gossiping about the intelligence of other academics. And you know, we hire and we promote and it's, you know, it's based on. On intelligence. What he. In part, I mean also accomplishment, of course. But the. His argument about reification went as follows. He claimed that psychometricians were committing a fallacy by talking about a. An entity that they called General Intelligence or G. Now, General Intelligence statistically arose from the finding that all of the different subtests on an IQ test or on pretty much any other measure of intellig that you want to call intelligence, they all are intercorrelated. That is contra the stereotype of the mathematician who can't put together a sentence or the poet who can't balance his checkbook. In general, if you are above average in verbal skill, you're also above average in quantitative skill. Maybe not as much, but they correlate. You're also going to be better than average in solving geometry puzzles and analogies and repeating back strings of digits. All of these things correlate with each other not perfectly statistically. You can talk about the variation that all these measures have in common. They're a technique of called factor analysis, which Gould explained pretty well in the Mismeasure of Man, where you can put a number to the degree to which someone is above average on all of the subtypes of intelligence. And in general they are. That's. Now Gould says, oh, that's a fallacy. Just because there's this statistical inter. Correlation doesn't mean that it actually exists. The thing is you have to explain why they correlate. It isn't magic. There is something going on in the brain that makes them all inter correlate. And again, contra Gould, we're getting a better and better idea of what it is. So people who have higher psychometric giving, that is, on average, all of their types of intelligence are way above average, a bit above average, lower than average, average, et cetera. That correlates with things like how big is your brain, how thick is your gray matter, how much white matter do you have interconnecting the different parts of the brain, how fast is your elementary reaction time, that is, how quick is the simplest possible mental process? So there has to be some explanation as to why they intercorrelate. It is not a fallacy of reification to ask why they intercorrelate. And indeed, that curiosity was satisfied. We know more and more about why they correlate. Namely, these are brains that function more efficiently.

[Sponsor Representative]

This is the best.

[David McRaney]

I hope you don't mind, I will quote you in my new book, because all of this is. It's a perfect convergence of things. And thank you for letting me go on that tangent. That's. I have never been more obsessed with. With anything than this particular obsession. I don't know why. It's everything I care about, all coming together. Psychology, neuroscience, words, linguistics, everything.

[Steven Pinker]

You know, it's not to say there isn't that there can't be fallacies of reification, but. But, you know, ironically, intelligence probably wasn't one of them. I mean, it is in the sense that there isn't like an IQ center in the brain, like one, you know, blob that's bigger and smarter people and smaller than others. It's distributed, it's a property. It's probably an aggregate sum of a lot of different physiological features that make brains more efficient. And in the aggregate, we call it G, but it is referring to, you know, to something, not just one isolated thing, but, you know, maybe a whole family of things that all push in a similar direction.

[David McRaney]

Yeah, it's, it's. I get the sense it's a complex thing. There's just an economy sitting somewhere in a bunker somewhere.

[Steven Pinker]

Yeah, exactly. That's a great example. So what is the economy? Where is the economy? Who controls the economy? It is distributed. But still, you can sensibly talk about GDP per capita or economic growth. You can. There is something that you're referring to. It's not as if it doesn't exist at all, but a lot of things exist that aren't you know, lumps of matter. It doesn't mean they don't exist. It just means that for something to exist and for something to be, you know, a hunk, you know, aren't the same thing. And by the way, that does relate to one of the themes of my book. Yeah, yeah, everyone knows, namely that there are social realities. Things like corporations, universities, institutions, laws, senators, all of which make complex modern life possible. Money. There's a sense in which it's not a thing. It's not like Scrooge McDuck is sitting on a big pile of coins or gold somewhere, or Fort Knox has all of the. The country's money supply. You know, money. Money is a. It's. It's common knowledge. What, what is the value of currency is that if I accept it in exchange for something of value, I know that other people will in turn exchange it in exchange for something of value. So on the other hand, it doesn't mean that these things don't exist. It doesn't mean there's no such thing as a, you know, as a law. There's no such thing as a. A Senator. This is my slight disagreement. It may be more terminology than anything with the Yuval Noah Harari, in his book Sapiens, he said that human life is based on fictions. Complex human social life, like corporations, like laws, like titles, like positions. You know, I think he's. He's right that a striking feature about humans is that a lot of our life is governed by things that you can't see. Social conventions, norms, understandings. And the reason that I'm interested in them is they exist because of common knowledge. What makes someone the boss? Well, everyone treats them as the boss, and everyone knows that. And everyone can expect everyone else to know that, but it doesn't mean that they don't exist at all. It doesn't literally mean they're fictions. I just would quibble with Harari as to whether fictions are. Is the right way to characterize them. They're not, you know, chunks of matter, but they exist in a different sense. And I would say they exist as common knowledge. That is, conventions that are propped up by the fact that everyone knows that everyone knows they exist.

[David McRaney]

I love this so much because it goes. It's some of the first things we talked about. We were trying to, like, figure out how anything works. Is what's in it. Was it, what is piety?

[Sponsor Representative]

What is truth?

[David McRaney]

What is justice? If it's an abstraction, does that mean it does not exist? Must it be concrete? Do I need to hold it in my hand. And the idea that language helps us coordinate around all manner of these things is beautiful and tantalizing to me. And I want to make sure I ask this question before we run out of any time here, because you address this specifically in the book. You talk about how common knowledge gives us the ability to coordinate. And so to phrase this sort of as a question, what happens when two or more people have common knowledge that alters the way we make complementary choices? The when it goes from, I'm not sure if they know that I know. I'm not sure if everyone has the same thing on their mind. How does that affect us? Whenever it goes from being. I'm not sure about that to okay, this is explicit. This is out there.

[Steven Pinker]

Yeah, no, it's a great, great question. I spent a lot of time in the book on that. So, you know, one extra idea to throw out there is that, you know, just as all of our institutions are our laws, our money, our positions of power are our conventions that are held up by common knowledge. I suggest that so are our informal social relationships. What does it mean for two people to be friends? Well, you know, it's not that they sign a contract. Each one knows that the other one knows that they know that the other one knows that they're friends. And that's what being friends is. And it's also true of being lovers. It's also true of when people are in some relationship of authority. One person decides, the other person gives way or obeys. That's a matter of common knowledge. He stands his ground because he knows the. That she will give way. She gives way because she knows that he'll stand his ground. And that's all there is to it. And that. And that's what props it, props it up. And when we lose face, that's a case where we maybe alter that understanding of who defers to whom. But what it means is that since we get a lot out of our relationships about being friends or being one person, having, you know, trusting another to make the decisions, or being in a relationship of exchange where people, a salesperson and a customer, there's sometimes when we have to transact business that contradicts one of those relationships or at least tests the possibility of moving from one kind of relationship to another. That can happen when friends start to approach the line of are they going to be romantic and sexual partners? Or when two people who are co workers, or in fact, say a student and a professor or a boss and a co worker want to become friends, There are often Kind of touchy moments. They're often enforced by the emotion of awkwardness or embarrassment if you behave in a way suitable for one relationship when you're in a different kind of relationship. But how do you ever make the transition or how do you ever do business that may contradict the relationship that's currently enforced? Let me just give some examples or let me actually announce the solution to that question before I give the examples. I argue that that's why we have tact, politeness, innuendo, euphemism, hints, genteel hypocrisy, all cases in which we don't want to explode a relationship that's in force, but we have to do something that contradicts them. A simple example is politeness. If you could pass the salt, that would be awesome. Now, you know, that doesn't, doesn't make a whole lot of sense. It's a kind of hyperbole. It's, you know, why are you pondering hypothetical counterfactual possible worlds at this moment at the dinner table? Well, we understand it as basically an imperative, give me the salt. But a problem with imperatives is it presupposes a relationship of kind of authority. You bossing around a servant or a butler. And if we're friends, I may not want to treat you like you're a servant, but I really do want you to pass me the damn salt. And that's why I'd say, can you pass the salt? Do you think you could pass the salt? If you could pass the salt, that'll be great. And so on. So indirect language, rituals, hypocrisy, politeness, all of these things are ways of avoiding signaling a relationship that we don't want to signal, and so on with other fraught situations like, like a bribe, like a veiled threat, like solicitation of a donation. I've gone to fundraising dinners at my university in which the Dean will say to the, as they say, to use a euphemism, high net worth individuals, rich guys, now everyone knows why, why we're there. That is, the dean is hoping that the high net worth individual will donate, you know, $10 million in exchange for naming rights for a professorship or a building. But it would kind of spoil the mood. The Dean said, okay, we know why we're here. How much are you going to give? Instead he says things like, or she we're counting on you to show leadership and to be a friend to the university and help us in our campaign for the future. All of these again, being euphemisms for A reality that would shatter the assumption that it's a convivial gathering of peers or friends.

[David McRaney]

We have, like authoritarian regimes and dictators and fascist governments. They seem to really, really, really try to avoid a certain kind of dissent that relies on common knowledge. And they seem to avoid that. That by encouraging something called pluralistic ignorance. I did a show about that a long time ago. I would like it in relation to this discussion. Could you remind us what that term means and how does that prevent coordination in situations like that?

[Steven Pinker]

Yeah, so in fact, you can say that despotic regimes don't actually care about dissent. They care about common knowledge of dissent. That is, if all. If the whole population is disgruntled, but none of them can act on it in cahoots with everyone else. At the same time, they can control everyone because as soon as one person gets up to protest, they can pick them off. If everyone were to stand up at the same time, they could overpower the regime. They could storm the palace, they could bring it to a halt with work stoppages. I quote the Gandhi character in the movie Gandhi, who when at one point he tells a British colonial officer, in the end, you will leave because 100,000 Englishmen simply cannot control 350 million Indians if the Indians refuse to cooperate. He could have said coordinate, and why couldn't they coordinate? Or what would would allow them to coordinate? And the answer is common knowledge. Common knowledge could come from broadcast, a publication that everyone reads. That's why authoritarian regimes don't have freedom of the press or freedom of. Of speech. It could come from everyone showing up in a public place and everyone seeing everyone else and seeing everyone seeing everyone else, which would allow them to coordinate. And authoritarian regimes are terrified of public protests. Conversely, democracies enshrine freedom of assembly as a fundamental right. All of these are mechanisms of regimes preventing common knowledge. People seeking it as the only thing possible way they can coordinate, refuse to cooperate, as the Gandhi character put it.

[David McRaney]

Pluralistic ignorance comes into play so often said this and I.

[Steven Pinker]

We didn't talk about.

[David McRaney]

No, no, yeah, we can talk about just to like sprinkle a little hot sauce on what you're about to say. The. There's so much bot driven. Let's mess with people's ability to coordinate when it comes to. We have this incredible power to coordinate now with online discussion discussions where a person in Alabama can talk to a person in Iowa who can talk to a person in San. We could all be in a way that was never before possible. But there's a great Way to disrupt that and to encourage pluralistic ignorance by keeping people in different, like information ecosystems despite the fact that we could possibly see eye to eye and coordinate. But yeah, pluralistic ignorance. I'm interested.

[Steven Pinker]

Oh yeah. So that's the case in which I would call it common misconception plus private knowledge. So pluralistic ignorance is the. Or a spiral of silence is the situation in which everyone thinks that everyone else believes something and no one actually believes it. So it was, I think, first documented in, at least experimentally, in a study of fraternities where it turns out that none of the bros in a fraternity actually thinks that it's a good idea to drink until they puke at pass out. Each one mistakenly thinks that, all the others think that it's cool and no one actually thinks it's cool. Everyone thinks it's stupid, but they feel they can't not do it because they would mistakenly that they would lose status in the group. There are many examples of that. Often spirals and sounds are enforced also by punishment. That is, if you express a certain view, you would get punished. People anticipate that and so falsify their views and then there's no way to know about what other people's views really are.

[David McRaney]

Yeah, this play has played out a zillion times historically. We're getting to experience some of it right now. You get the sense everybody thinks the same thing, but nobody's saying it out loud. Am I the only person that sees this?

[Steven Pinker]

Exactly right. Yes.

[David McRaney]

So I'm wondering, with this book, with this most recent book, who do you hope reads this book and what do you hope they get out of it?

[Steven Pinker]

I think that anyone who's just interested in what makes us tick in social life and the various puzzles, mysteries, fads, crashes, bubbles, rituals, hypocrisies, just human social life on scales from couples to societies. I like to think that people get more insight as to how that works and sometimes how it doesn't work from, from, from reading the book. And this I also like. I, I season it with cartoons, jokes, sitcoms, movie plots, not, not as a gimmick, but that's really why we have jokes and, and sitcoms and comedies of manners. They actually do explore the paradoxes and puzzles of common knowledge. Now close your eyes and sleep, sleep, sleep.

[David McRaney]

That is it for this episode of the you are not so smart podcast. For links to everything we talked about.

[Podcast Host (David McRaney)]

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[David McRaney]

My name is David McCraney.

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[Steven Pinker]

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