Steven Pinker just told me something that honestly blew my mind. He said that Malcolm Gladwell's recent cancellation attempt was not only predictable, it was mathematically inevitable.

There is another thing. As a social media shaming mob, why do people feel the urge to pile on and collectively punish someone who says something that seems to violate some moral norm?

And here's the kicker. Pinker started coming years ago using something called common knowledge theory.

Common knowledge means 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.

Picture this. You're in a meeting where everyone privately thinks the boss's idea is stupid, but nobody speaks up. Then one person finally says what everybody's thinking and suddenly the whole room erupts in agreement. What just happened? According to Steven Pinker, you just participated in one of the most powerful forces shaping human civilization. And today we dive deep into it with one of the foremost public intellectuals of our time. Let's go. Professor Steven Pinker, welcome back to the into the Impossible podcast.

Thank you.

In this book you've written that civilization itself depends on common knowledge. But my first question to you is what happens when that common knowledge is wrong? Or even when technologies like artificial intelligence threaten us by hallucination? What happens to the very foundations of what we thought was secure?

The answer is we don't know. Track record in general of predicting the downstream consequences of, of technology are poor. Even the best superforecasters are at chance for cut and dry questions five years out, let alone open ended questions like what will happen to society, let alone civilization. I don't know if when social media were introduced 15 years ago, if people could have predicted social media shaming mobs, the spread of disinformation, the, the encouragement of conspiracy theories. I bet people thought Facebook was a rather benign and minor phenomenon. Likewise with the effects of the Internet, of cable news programs, let alone electricity, steam power, the automobile, the telephone and telegraph, television and so on.

Along those lines, it came to me to mind when I read these books and your wonderful writing. Throughout the years, I always try to form, you know, kind of the opposite, the strawman version of it. But to me, the opposite of common knowledge is sort of expert knowledge. And there's a term for this which is ironic because it's sort of tautological. It's a shibboleth. A shibboleth is sort of an abstract term or something of art that only the insiders really know about. It's also A shibboleth. To say that what a shibboleth is, of course, it's tautological.

Why is there, you know, such a prevalence nowadays in the age of reason and science and rationality as you promote? Why do conspiracy theories, UFO sightings, why do they spawn such explosive, you know, violent rhetoric? Is that because of this chasm, this, this gap between expert knowledge and common knowledge, that people abhor the vacuum and rush to fill it in?

I'm not so sure. So the common knowledge as the theme of the book, when everyone knows that everyone knows, the starkest contrast is with private knowledge. That is, what I really explore is not a lot of people knowing something versus only a few people knowing something, but rather the difference between everyone know something and everyone knowing that everyone knows it. That's really what the book is about. Not so much about who knows what, but about that vital difference. Because that difference, it turns out, drives a lot of phenomena. It is, to begin with, necessary for coordination for two people being on the same page, meeting at a certain time and place, observing certain standards, holding up certain norms, belonging to following conventions like paper currency, driving on the right the words of a language. I suggest that it also drives our social relationships, that what it means for people to be friends or lovers or superior and subordinate or transaction partners is that each one knows that the other one knows that each one knows that the other one knows that they have that relationship.

And the phenomena that I talk about are not so much a few people knowing something versus a lot of people knowing it, but rather everyone knowing something versus everyone knowing that everyone knows it. And I suggest that many cases we try to prevent common knowledge. Even if all of us share the same knowledge. We tend to ignore the elephant in the room. We resort to innuendo and euphemism so we don't blurt out exactly what we mean. That's the main contrast. Now I can also say a few words about conspiracy theories and quack cures and UFOs and paranormal woo woo. It's a different phenomena, one that I actually spent more time discussing in my previous book, Rationality.