How people keep track of who knows what about who knows what about who knows what...

What is it about?

Common knowledge - when everyone knows that everyone knows, and everyone knows that, ad infinitum - is essential to human coordination, from social relationships to corporations, nations, and the global system. But how can an infinite number of "I know that she knows that I know..." propositions fit inside a finite head? The investigators (including Steven Pinker, author of the New York Times Bestseller "When Everyone Knows That Everyone Knows...: Common Knowledge and the Mysteries of Money, Power, and Everyday Life") propose people achieve coordination by tracking a few layers of who knows what who else knows and by treating publicly witnessed events as licensing implicit common knowledge. In two studies, participants inferred that public events justified arbitrarily deep mutual understanding, though they sometimes overextended or confused knowledge states. This mix of valid and faulty reasoning helps explain how humans achieve large-scale coordination while also being prone to missteps, from everyday faux pas to collective dilemmas such as bubbles, bank runs, panic buying, and strategic miscalculations.

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Photo by Vinicius "amnx" Amano on Unsplash

Photo by Vinicius "amnx" Amano on Unsplash

Why is it important?

At smaller, personal scales, people's failure to keep track of who knows what about who knows what may lead to faux pas and snafus such as inadvertently blurting out a secret, having a seemingly obvious implication go over one’s head, playing Alphonse-and-Gaston at a four-way stop sign, writing in opaque academic jargon, and being the sole applauder between movements of a sonata. At larger, collective scales, it may consist of pluralistic ignorance (when everyone assumes that everyone believes some-thing, such as support for a regime, but no one actually believes it), commitment to an inferior technological standard (as in VHS vs. Betamax), misjudging an enemy’s resolve in an international game of chicken, or acting on rumors that reverberate into self-fulfilling bubbles, hoarding, panic buying, and bank runs

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