Steven Pinker, "When Everyone Knows That Everyone Knows...: Common Knowledge and the Mysteries of Money, Power, and Everyday Life" (Scribner, 2025)

In this episode of NBN Book of the Day, cognitive scientist and best-selling author Steven Pinker discusses his latest book, *When Everyone Knows That Everyone Knows: Common Knowledge and the Mysteries of Money, Power, and Everyday Life*. Pinker explores the concept of 'common knowledge'—not just knowing something, but knowing that others know it, and knowing that they know you know it, ad infinitum. He illustrates how this recursive awareness underpins human coordination in everything from social interactions and romantic advances to political revolutions, currency systems, and international diplomacy. Using examples ranging from polite requests for the salt to Israel’s nuclear ambiguity, Pinker reveals how common knowledge enables cooperation, maintains power structures, and preserves social harmony. He also examines how involuntary expressions like blushing, crying, and laughter function as powerful, involuntary signals that generate shared awareness, reinforcing social bonds or challenging hierarchies. The conversation concludes with a reflection on truth, arguing that while humans naturally gravitate toward comforting myths, only deliberately engineered institutions like science and journalism can reliably uncover objective truth. The episode offers a profound lens for understanding the hidden mechanics of social life.