Steven Pinker on Coordination, Common Knowledge, and the Retreat of Liberal Enlightenment

Steven Pinker in conversation with Tyler Cowen, September 2025. Episode 255 of Conversations with Tyler, recorded around publication of Pinker’s book When Everyone Knows That Everyone Knows… Common Knowledge and the Mysteries of Money, Power, and Everyday Life. The conversation is the most technically precise statement of Common Knowledge as a social-science concept in Pinker’s public work, alongside a frank assessment of liberal enlightenment in 2025.

Key ideas

• Common knowledge is the infrastructure of social order — money, authority, and law depend not merely on what individuals believe, but on the infinite recursive structure: everyone knows that everyone knows that… The dots in the book’s title mark the infinity. Without common knowledge, currency collapses (bank runs), authority evaporates (regime change when protesters see each other seeing each other), and law loses its grip. GDP would ‘tank’ in the absence of this infrastructure.
• Eye contact is an instant common knowledge generator — it is self-referential: you are looking at the part of the person who is looking at the part of you. This is why eye contact is so potent across species and why it can grant common knowledge without explicit recursive reasoning.
• Schelling points are common salience, not common knowledge — a coordination equilibrium in the absence of recursive mentalising. What makes a point a Schelling point is not logic or intrinsic value but that it is salient enough to pop into everyone’s mind simultaneously. At this point, Pinker says, game theory leaves off and ‘human whimsy, caprice, even poetry’ take over.
• Benign hypocrisy and noble lies sustain institutions — the paper bag over the whiskey bottle, escort services, Taiwan’s non-recognised sovereignty, Israel’s nuclear ambiguity: in each case the common pretence preserves an authority or balance that open acknowledgement would destroy. Pinker endorses Robin Hanson’s framing.
• Liberal enlightenment is in retreat because it is counter-intuitive — tribalism, deference to authority, and conformity fit human nature more naturally than checks and balances, universal rights, or markets. Liberal enlightenment requires continuous active maintenance; it is not a natural equilibrium. This is not pessimism about outcomes but diagnosis of the mechanism of backsliding.

Sections

• Common knowledge and the foundations of currency, authority, and law
• Coordination vs common knowledge: the traffic-circle problem and knife-edge properties of formal models
• Eye contact as an instant common-knowledge generator; the coral example
• Schelling points, salience, and the limits of game theory
• Noble lies, benign hypocrisy, and strategic ambiguity (Taiwan, Israel)
• Aumann’s theorem: rational agents cannot agree to disagree; the corollary against speculative trade
• Preferences vs beliefs: chocolate, Hitchcock, Dylan
• Liberal enlightenment in retreat: the 2025 verdict
• Why liberal enlightenment is counter-intuitive and requires maintenance
• LLMs and linguistics: what transformer architecture implicitly builds in; what it omits
• Harvard grade inflation; holistic admissions as ‘mysticism’
• Next project: Enlightenment Now retrospective

Cross-references

• Common Knowledge — new concept page; this episode is the primary source
• Steven Pinker on Language, Reason, and the Future of Violence — companion episode, 2016
• Steven Pinker — speaker page