Common Knowledge and Social Coordination in StarTalk Special Edition with Steven Pinker

Overview

In this StarTalk Special Edition, Neil deGrasse Tyson hosts a discussion with Steven Pinker about common knowledge, the remarkably human capacity to make private beliefs public in order to coordinate behavior at scales from everyday conversations to large scale institutions and political events. The dialogue weaves together psychology, game theory, linguistics, and evolutionary perspectives to uncover how common knowledge emerges, how it sustains civilization, and how it can break down.

Defining Common Knowledge

The speakers distinguish between private knowledge, which one person may hold, and public knowledge, which others know that you know, that they know you know, and so on. Common knowledge arises not merely from awareness but from the sense that others share and act on the same understanding. Language, public rituals, and salient social cues are key generators, enabling many layers of mutual knowledge to be established in a single moment when a public signal is available to all.

Nonverbal Signals and Public Cues

A large portion of the discussion centers on nonverbal knowledge generators such as laughing, crying, blushing, eye contact, and facial expressions. Pinker and Tyson illustrate how these signals convert private states into observable public signals, shaping how others perceive, react to, and coordinate with us. Eye contact, in particular, is highlighted as a potent generator of common knowledge because it couples minds through direct attention and shared focus.

Culture, Signaling, and Relationships

The conversation explores how different cultures prize different forms of relationships—communal sharing, hierarchical authority, and transactional exchange—and how common knowledge mediates what is expected in each context. The discussion includes anecdotes and cultural references to show how norms and conventions, like what day to stay home, or whether a statement about a bribe is plausible, depend on shared assumptions about others' beliefs and actions.

From Private to Public: Emperors and Closet Doors

One central metaphor is the emperor in The Emperor's New Clothes, where a public admission converts private knowledge into common knowledge, altering power dynamics and ridiculing deference. The guest panelists discuss metaphors like the closet and saving face, explaining how euphemism and innuendo sustain privacy while still coordinating behavior in ways that preserve relationships and reputations.

Economics, Politics, and Real-World Consequences

The talk connects common knowledge to economic and political life, including currency, bank runs, and political momentum. Roosevelt's “the only thing we have to fear is fear itself” is discussed as a diagnosis of common knowledge dynamics in crisis. The dialogue also touches on campaign signaling, widely watched media moments, and the ways in which norms can be flouted, copied, and destabilized by leaders who redefine what is acceptable in public discourse.

Norms, Civility, and the Path Forward

The guests discuss the breakdown of civility and the polarization of public life, proposing norms like epistemic humility, civil disagreement, and cooperative inquiry as essential to science, journalism, and governance. They present a view of argument as a process of converging on truth through information exchange, rather than win-lose battles, and connect this to broader scientific practice and social progress.

Cosmic Perspective and Conclusion

In closing, Pinker and Tyson reflect on the human mind as perhaps the universe’s most complex object. The conversation leaves the listener with a sense of how the study of common knowledge can illuminate not only social dynamics but the potential for science to guide better collective decision making and to preserve the best aspects of civilization.