Steven Pinker on Common Knowledge

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We'd love to hear from you. Today is September 2nd, 2025, and my guest is cognitive psychologist and author Stephen Pinker. The John Stone family professor of psychology at Harvard University. His latest book and the subject of today's conversation is When Everyone Knows That Everyone Knows common knowledge and the mysteries of money, power, and everyday life. Stephen, welcome to Econ Talk.

Thank you. At the heart of the book is this idea of common knowledge, which uh has uh an everyday meaning, but you also mean it in a more technical way. Uh, what do you mean by common knowledge? Common knowledge refers to the state where A knows something, B knows it, A knows that B knows it, B knows that A knows it, A knows that B knows that A knows it ad infinitum. And part of this, there's an attempt at some point in the book to

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