The Spiral of Awareness

What Fuels Revolution, Social Embarrassment and Public Acclaim? It’s Common Knowledge. WHEN EVERYONE KNOWS THAT EVERYONE KNOWS…: Common Knowledge and the Mysteries of Money, Power, and Everyday Life, by Steven Pinker.

In a new book, the Harvard psychologist Steven Pinker argues that an awareness that everyone knows what you know is a powerful driver of human social life.

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.

- Author: Dennis Duncan, The New York Times

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