WHEN EVERYONE KNOWS THAT EVERYONE KNOWS…: Common Knowledge and the Mysteries of Money, Power, and Everyday Life, by Steven Pinker
What is common knowledge? For the type of social psychology at the heart of Steven Pinker’s new book, it’s not enough to say that it occurs when everybody knows something; everybody also has to know that everybody else knows it.
Take the story of the emperor’s new clothes. When the emperor parades naked through the town, nobody really sees the fine suit he believes he is wearing. But in each person’s mind is the slim possibility that everyone else is seeing something different. It takes the innocent observation of a child to turn many cases of identical but private knowledge into common knowledge.
Needless to say, this is a powerful thing. What if, instead of a vain emperor, we imagine a repressive dictator? Once everybody knows that everybody knows the regime is corrupt, the possibility of organized resistance arises. Or as Pinker, the Harvard psychology professor and prolific author, puts it, “As the pluralistic ignorance unravels, the protest can snowball and take in a growing number of defectors who had been falsifying their loyalty.” The key is coordination. How do I signal to you that I know you know?
Of course, the significance of common knowledge is not limited to the political sphere. It is, Pinker argues, “a keystone in understanding the social world.” The first part of “When Everyone Knows That Everyone Knows…” offers a summary of work on common knowledge over the last half century by psychologists, mathematicians, economists and game theorists.
We start with the best known of game theory’s thought experiments, the prisoner’s dilemma. The scenario is this: Two crooks, partners in crime, have been apprehended and sentenced to six months in the lockup. But the prosecutor knows that another, bigger crime has also been committed by the pair; there just isn’t enough evidence to convict. So each crook is offered — separately — a plea deal: Rat on your partner and you can go free while he gets 10 years. However, if they both rat on each other, they’ll both get six years.
So, to recap: If both prisoners keep mum, they can both sit in jail for six months; if they both rat on each other, they’ll both do six years; but if one keeps mum while the other rats him out, the rat walks free while consigning his accomplice to a decade in the slammer.
Played as a one-off, the best strategy is simply to rat. But if the game is played repeatedly, across a population where players can see and remember how other players behaved — and know that their own decisions can be seen — then collaborative strategies begin to emerge, the situation becoming one in which “cheaters will eventually be excluded from beneficial cooperation.”
Pinker leads us through a series of similar games and inductive reasoning puzzles, along with experiments he undertook with his graduate students at Harvard. These were designed to analyze their subjects’ emotional responses to certain scenarios, most memorably being made to sing the chorus to Adele’s “Rolling in the Deep” in public. Pinker suggests that coordination has helped drive the evolution of non-linguistic cues like laughter, crying and glaring. A blush, for example, represents a social signal that he decodes as “Yes, I screwed up, but I know I screwed up, according to standards I understand and share.” The fact that a blush is an autonomic reflex makes it more trustworthy than a verbal apology.
All of this material is well organized and clearly explained. The problems arise from Pinker’s inability to keep himself out of the narrative. The line between engagingly informal and distractingly unfiltered is a delicate one, and there is a certain charm to the affable, playfully bumptious professor who can’t resist the provocation of scare quotes around the word “microaggressions,” or who interrupts his description of the induction problem formerly known as the puzzle of the cheating wives with a full paragraph of eye-rolling at the wokeness of its many reformulations (which have involved swapping out wives for husbands, muddy children and girls in red or white hats, among other variations).
Too often, however, the first-person interventions are ill judged, and the effects they produce are surely not the ones intended. A section on embarrassment — with the Adele experiment — is capped with a personal anecdote in which Pinker interprets the phrase “black tie optional” on an invitation as an opportunity to wear a dinner suit, rather than permission not to. The ensuing situation, and the rather delicious phrasing, “I mistakenly assumed it was the default, and on the designated evening found myself as the only man among the hundreds of luminaries decked out in a tuxedo,” could have been scripted by the team at “Frasier.” Nevertheless, the story is intrusive and unnecessary, its self-abasement really self-delight.
In an interesting section on why we assign more moral weight to anonymous charity than to public giving, Pinker considers the relative generosity of Bill Gates (a public giver) and Steve Jobs (an anonymous one). He laments that “the revealed anonymity burnished Jobs’s reputation as a philanthropist … despite his having given away at most a thousandth of what Gates did.” This may be accurate, but it sits awkwardly with the thanks offered to Gates (for “patient guidance”) in the book’s preface and the blurb from Gates that appears on the back cover (“One of the most insightful books I’ve read about what makes us human”). Pinker’s point still stands — just about. But, again, there’s a garrulous naïveté about the distinction between personal and professional that risks undermining the patient work of the book’s larger teaching objective.
Early on in “When Everyone Knows That Everyone Knows…,” in a passage about how less adversarial strategies can make for more productive debate, Pinker takes aim — half-cryptically — at a few bêtes noires:
At the most refined levels of intellectual colloquy, in debating forums named after venerable British universities and periodicals whose names are permutations of New York, London, Review, Literary, Books, and Times, the customary style of argumentation is gladiatorial combat. … It’s an entertaining sport, but a dubious way to seek the truth.
Can he mean us? It reads as defensiveness, another irruption of the author’s ego, a petulant attempt to spike the critics’ guns. It also betrays a basic misunderstanding of what a newspaper review sets out to do. A book can be bad without its thesis being untrue. That, at least, should be common knowledge.
WHEN EVERYONE KNOWS THAT EVERYONE KNOWS…: Common Knowledge and the Mysteries of Money, Power, and Everyday Life | By Steven Pinker | Scribner | 364 pp. | $30
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