Take your little one with you while you're driving through Penn Station and you'll find yourself with a lot of explaining to do. Walking through the concourse of the Long Island Rail Road, my son was puzzled by the close proximity of three chicken restaurants—Chick-fil-A, Raising Cane's and Pollo Campero—and by the fact that a store called Gotham News seemed to primarily sell candy and bottled water. He also wanted to know why some people were drinking from cans in brown paper bags while walking or waiting. “Why do they use these bags?” he asked.
Where to start? Brown bagging is one of those social practices that continues to seem meaningless even after it has been explained. As we all know, the idea is that the bags conceal the drink being consumed, allowing drinkers and police officers to ignore bans on public drinking. Of course, bags don't actually hide anything; in fact, they are designed specifically for alcohol consumption and definitely signal it. (You would never think of drinking a bottle of Fijian water that was in a paper bag.) Overall, the thought process is bizarre. The drinkers know that the cops know that they drink, and the cops know that the drinkers know that they know. But the police pretend that they don’t know anything, reserving the right to suddenly “understand” what is happening if the drunkard begins to disrupt the order. Meanwhile, non-drinkers benefit from a train station that appears more genteel than it actually is.
These strange whirlpools of convoluted logic cannot be typical of our thinking; of course, human affairs are usually more straightforward. But it is precisely this assumption that Steven Pinker challenges in his new book.”When everyone knows that everyone knows. . . : General knowledge and secrets of money, power and everyday life.” The mystery of who-knows-who-knows-what, always fascinating to fans of detective novels and spy thrillers, has long occupied psychologists and game theorists. “As a cognitive scientist, I have spent my life wondering about how people think,” Pinker writes. “So my main fascination would have to be how people think about what other people think, and how they think about what other people think they think, and how they think about what other people think.” think that they think that they think.” Such recursive cycles of thinking, Pinker argues, are not just a puzzle for specialists; they are central to how we live.
“Common knowledge” is generally how we describe those ideas or facts that we all know: say, the Pledge of Allegiance or the meaning of LOL. But Pinker has a more specific definition in mind. General knowledge, he explains, is not only what we know, but what we know is known. This is different from “mutual knowledge”, which is shared by several people but not openly. If you know that the emperor is naked, and I know that the emperor is naked, then this is mutual knowledge: neither of us can be sure that the other knows. On the contrary, if I know exactly what you know, and you know exactly what I know, then this knowledge is common between us. “When the little boy said the emperor was naked, he didn’t tell anyone anything they didn’t already know,” Pinker writes. However, by “blurting out what every observer could see”—Pinker cites such idioms as “letting the cat out of the bag” or getting it “out there”—he made the emperor's nakedness public knowledge, which was enough to change everyone's view of the emperor “from obsequious deference to ridicule and contempt.”
The story of the naked emperor shows how shared knowledge enhances collective action. Everyone in the Imperium knows that the Emperor is a fool, but no one wants to risk criticizing him. Every man for himself. This is what game theorists call a coordination problem. If everyone acted together, revolution would be possible, but when individuals act alone, they face punishment; what's worse is that they have an incentive to work against the common good, such as by impersonating each other or denying each other's reality. However, once the emperor's nudity became public knowledge, the problem of coordination could be solved.
Life is full of coordination problems that can be solved by common knowledge, Pinker writes. In the simplest example, two people trying to pass through a narrow doorway at the same time can coordinate most effectively with each other if they consciously adhere to the same conventions about who should have priority. (They may know that they agree that priority goes to whoever arrives first, or whoever is the boss, or whoever is “ladies first.”) In America, it is common knowledge that you drive on the right, not the left. While reading Pinker, I thought that in New York it is common knowledge that pedestrians often wait to cross while standing on the street rather than on the side of the road. City drivers know they need to take this into account, and pedestrians know they know it, and vice versa. Try it somewhere else and you will take your life into your own hands.
Large groups of people, Pinker writes, often solve the problem of coordinating and holding themselves together by cultivating beliefs that are “generally accepted but not easily verifiable.” Pinker cites the view on the American right “that the 2020 presidential election was stolen,” as well as the view “among the young, educated left” that “being a man or a woman has nothing to do with biology.” It is precisely because such ideas are controversial and not obvious (they are far from saying “that the sun rises in the east,” writes Pinker) that they serve as reliable signals of group membership. If someone tells you that they believe in Pizzagate, you can be pretty sure that they hold many related beliefs, and coordination can begin.
Ideas like these make people who are actually completely different feel similar. General knowledge is taken very seriously; it becomes a litmus test of belonging and a driving force of division. It shapes the course of society and affects us as individuals. However, according to Pinker, it has much in common with more innocuous beliefs and conventions, such as traffic rules. For fans of “KPop Demon Hunters” it is an article of faith that singer EJAE is a generational talent due to her extraordinary vocal range that seems to span two and a half octaves; within MAGAit is common knowledge that the radical left is trying to indoctrinate children into gender ideology; Within certain groups of artificial intelligence researchers, everyone knows that everyone thinks that superintelligence may soon take over the world. How might life be different if we viewed such beliefs not as ideas necessarily attractive in themselves, but as uniquely effective solutions to coordination problems?
If people who strive to work together cultivate shared knowledge, they also control, suppress, and hide it, both to maintain group cohesion and to avoid grouping with people they don't like. Members of a religious community may punish heretics who question accepted knowledge; in doing so, they sometimes create opportunities for people to confirm their group membership, facilitating punishment. The more people join the crowd, the more everyone believes that everyone believes the dogma. (Pinker argues that it is this dynamic that lies at the heart of cancel culture.) “The shy leader’s inner circle may act as if everything is fine”; perhaps those within the circle are trying to prevent mutual knowledge of his evasion (everyone knows about it) from becoming common knowledge (everyone knows that everyone knows about it). Likewise, when an unstable leader makes autocratic statements, his aides may insist that he is “only joking.” You could say they put a brown bag on the beer.
Yet in other circumstances, avoidance of common knowledge can be subtle and even pleasant. Consider two people who like each other: They may agree to hang out, but they do so in a way that doesn't make their mutual attraction known to them. (Two friends can enjoy a hike, right?) What a couple hides can strengthen the electricity between them or provide shelter if the charge dissipates. Pinker recalls an episode of Seinfeld in which George tells Jerry and Elaine about a recent date. “She invites me to coffee at twelve o’clock in the evening,” George recalls. “And I'm not getting up. “No, thank you. I don't want coffee. It keeps me awake. It’s too late for me to drink coffee.” I told her this. Such stupid people should not be allowed to live!” Why wasn't his date included in her proposal beforehand? Pinker ultimately characterizes this kind of indirection as providing “plausible deniability of common knowledge.” George knows where he wants to go for the evening, and apparently so does she, but her performative ignorance gives both parties a chance to de-escalate tensions. It can be helpful to pretend that you are just friends.
