Steven Pinker’s "When Everyone Knows That Everyone Knows" is an exploration of common knowledge—how it transforms social dynamics, enables coordination, and why societies often avoid it. Here are the main points, strengths, and weaknesses of the book, and reasons it is a worthwhile read:
Common knowledge—when everyone knows that everyone else knows something, and this is widely recognized—is crucial for social coordination, large-scale collective action, and cultural norms.newscientist+3
The difference between private knowledge and common knowledge explains phenomena like self-censorship, preference falsification, and pluralistic ignorance, which allow disliked norms or oppressive regimes to persist until a public sign signals shared dissent.nytimes+1
Social conventions (like money, traffic rules, public demonstrations) function because they are common knowledge, not just privately held beliefs.simonandschuster+2
Pinker uses game theory and psychological insight to show how common knowledge can lead to sudden, radical social change—such as revolutions—when enough people realize their shared views and act together.newscientist+1
The book explores the paradoxical tendency for people and societies to sometimes actively avoid common knowledge, creating rituals, hypocrisy, and veiled communications to maintain ambiguity and avoid controversy.simonandschuster
Pinker connects common knowledge to ethical and political questions, including debates about “cancel culture” and public censorship, suggesting these efforts are attempts to control what becomes common knowledge.observer+1
Pinker presents complex logical, philosophical, and psychological ideas with clarity and wit, using relatable examples from pop culture, history, and everyday life (e.g. game theory dilemmas, the "Emperor's New Clothes" story).observer+2
The book offers a fresh framework for understanding how social change succeeds or fails, and why norms persist far past their real popularity.psychologytoday+1
Pinker’s synthesis of research from game theory, cognitive science, and social psychology is thorough, making abstract concepts accessible to general readers.stevenpinker+2
Some reviewers find parts of the book dry or overly abstract, especially compared to Pinker’s more narrative-driven earlier works.observer
Pinker’s treatment of controversial topics (especially “cancel culture” and censorship) can seem too rational and simplistic, glossing over the emotional and irrational complexities of real-world social conflict.newscientist+1
At times, Pinker’s reliance on logical reasoning risks underestimating the difficulty of resolving deeply embedded social tensions and misconceptions.observer
The book sheds light on why certain norms are hard to challenge, why collective action can suddenly become possible, and why silence or hypocrisy can dominate public life.nytimes+2
Pinker’s ideas offer readers new tools and perspectives for thinking about political change, social reform, ethical debate, and everyday coordination challenges.stevenpinker+1
For academics, policy thinkers, and anyone interested in collective behavior, the book provides a rigorous and thought-provoking account of the mechanics underlying major shifts in culture and society.stevenpinker+1
Overall, "When Everyone Knows That Everyone Knows" is a stimulating, challenging book that makes a vital—if sometimes abstract—contribution to understanding how societies can change, stagnate, or coordinate, all through the hidden but powerful force of common knowledge.nytimes+2