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When Everyone Knows That Everyone Knows...: Common Knowledge and the Mysteries of Money, Power, and Everyday Life
From one of the world’s most celebrated intellectuals, a brilliantly insightful work that explains how we think about each other’s thoughts about each other’s thoughts, ad infinitum. It sounds impossible, but Steven Pinker shows that we do it all the time. This awareness, which we experience as something that is public or “out there,” is called common knowledge, and it has a momentous impact on our social, political, and economic lives.
Common knowledge is necessary for coordination, for making arbitrary but complementary choices like driving on the right, using paper currency, and coalescing behind a political leader or movement. It’s also necessary for social everything from rendezvousing at a time and place to speaking the same language to forming enduring relationships of friendship, romance, or authority. Humans have a sixth sense for common knowledge, and we create it with signals like laughter, tears, blushing, eye contact, and blunt speech.
But people also go to great lengths to avoid common knowledge—to ensure that even if everyone knows something, they can’t know that everyone else knows they know it. And so we get rituals like benign hypocrisy, veiled bribes and threats, sexual innuendo, and pretending not to see the elephant in the room.
Pinker shows how the hidden logic of common knowledge can make sense of many of life’s financial bubbles and crashes, revolutions that come out of nowhere, the posturing and pretense of diplomacy, the eruption of social media shaming mobs and academic cancel culture, the awkwardness of a first date. Artists and humorists have long mined the intrigues of common knowledge, and Pinker liberally uses their novels, jokes, cartoons, films, and sitcom dialogues to illuminate social life’s tragedies and comedies. Along the way he answers questions
Why do people hoard toilet paper at the first sign of an emergency? Why are Super Bowl ads filled with ads for crypto? Why, in American presidential primary voting, do citizens typically select the candidate they believe is preferred by others rather than their favorite? Why did Russian authorities arrest a protester who carried a blank sign? Why is it so hard for nervous lovers to say goodbye at the end of a phone call? Why does everyone agree that if we were completely honest all the time, life would be unbearable?
Consistently riveting in explaining the paradoxes of human behavior, When Everyone Knows That Everyone Knows… invites us to understand the ways we try to get into each other’s heads and the harmonies, hypocrisies, and outrages that result.
Common knowledge is necessary for coordination, for making arbitrary but complementary choices like driving on the right, using paper currency, and coalescing behind a political leader or movement. It’s also necessary for social everything from rendezvousing at a time and place to speaking the same language to forming enduring relationships of friendship, romance, or authority. Humans have a sixth sense for common knowledge, and we create it with signals like laughter, tears, blushing, eye contact, and blunt speech.
But people also go to great lengths to avoid common knowledge—to ensure that even if everyone knows something, they can’t know that everyone else knows they know it. And so we get rituals like benign hypocrisy, veiled bribes and threats, sexual innuendo, and pretending not to see the elephant in the room.
Pinker shows how the hidden logic of common knowledge can make sense of many of life’s financial bubbles and crashes, revolutions that come out of nowhere, the posturing and pretense of diplomacy, the eruption of social media shaming mobs and academic cancel culture, the awkwardness of a first date. Artists and humorists have long mined the intrigues of common knowledge, and Pinker liberally uses their novels, jokes, cartoons, films, and sitcom dialogues to illuminate social life’s tragedies and comedies. Along the way he answers questions
Why do people hoard toilet paper at the first sign of an emergency? Why are Super Bowl ads filled with ads for crypto? Why, in American presidential primary voting, do citizens typically select the candidate they believe is preferred by others rather than their favorite? Why did Russian authorities arrest a protester who carried a blank sign? Why is it so hard for nervous lovers to say goodbye at the end of a phone call? Why does everyone agree that if we were completely honest all the time, life would be unbearable?
Consistently riveting in explaining the paradoxes of human behavior, When Everyone Knows That Everyone Knows… invites us to understand the ways we try to get into each other’s heads and the harmonies, hypocrisies, and outrages that result.
384 pages, Hardcover
First published September 23, 2025
630 people are currently reading
8734 people want to read
About the author
Steven Pinker
69 books10.6k followersSteven Arthur Pinker is a prominent Canadian-American experimental psychologist, cognitive scientist, and author of popular science. Pinker is known for his wide-ranging explorations of human nature and its relevance to language, history, morality, politics, and everyday life. He conducts research on language and cognition, writes for publications such as the New York Times, Time, and The New Republic, and is the author of numerous books, including The Language Instinct, How the Mind Works, Words and Rules, The Blank Slate, The Stuff of Thought, The Better Angels of Our Nature, The Sense of Style, and most recently, Enlightenment Now: The Case for Reason, Science, Humanism, and Progress.
He was born in Canada and graduated from Montreal's Dawson College in 1973. He received a bachelor's degree in experimental psychology from McGill University in 1976, and then went on to earn his doctorate in the same discipline at Harvard in 1979. He did research at the Massachusetts Institute of Technology (MIT) for a year, then became an assistant professor at Harvard and then Stanford University. From 1982 until 2003, Pinker taught at the Department of Brain and Cognitive Sciences at MIT, and eventually became the director of the Center for Cognitive Neuroscience. (Except for a one-year sabbatical at the University of California, Santa Barbara in 1995-6.) As of 2008, he is the Johnstone Family Professor of Psychology at Harvard.
Pinker was named one of Time Magazine's 100 most influential people in the world in 2004 and one of Prospect and Foreign Policy's 100 top public intellectuals in 2005. He has also received honorary doctorates from the universities of Newcastle, Surrey, Tel Aviv, McGill, and the University of Tromsø, Norway. He was twice a finalist for the Pulitzer Prize, in 1998 and in 2003. In January 2005, Pinker defended Lawrence Summers, President of Harvard University, whose comments about the gender gap in mathematics and science angered much of the faculty. On May 13th 2006, Pinker received the American Humanist Association's Humanist of the Year award for his contributions to public understanding of human evolution.
In 2007, he was invited on The Colbert Report and asked under pressure to sum up how the brain works in five words – Pinker answered "Brain cells fire in patterns."
Pinker was born into the English-speaking Jewish community of Montreal. He has said, "I was never religious in the theological sense... I never outgrew my conversion to atheism at 13, but at various times was a serious cultural Jew." As a teenager, he says he considered himself an anarchist until he witnessed civil unrest following a police strike in 1969. His father, a trained lawyer, first worked as a traveling salesman, while his mother was first a home-maker then a guidance counselor and high-school vice-principal. He has two younger siblings. His brother is a policy analyst for the Canadian government. His sister, Susan Pinker, is a columnist for the Wall Street Journal and the author of The Sexual Paradox and The Village Effect.
Pinker married Nancy Etcoff in 1980 and they divorced 1992; he married Ilavenil Subbiah in 1995 and they too divorced. He is married to the novelist and philosopher Rebecca Goldstein, the author of 10 books and winner of the National Medal of the Humanities. He has no children.
His next book will take off from his research on "common knowledge" (knowing that everyone knows something). Its tentative title is: Don't Go There: Common Knowledge and the Science of Civility, Hypocrisy, Outrage, and Taboo.
He was born in Canada and graduated from Montreal's Dawson College in 1973. He received a bachelor's degree in experimental psychology from McGill University in 1976, and then went on to earn his doctorate in the same discipline at Harvard in 1979. He did research at the Massachusetts Institute of Technology (MIT) for a year, then became an assistant professor at Harvard and then Stanford University. From 1982 until 2003, Pinker taught at the Department of Brain and Cognitive Sciences at MIT, and eventually became the director of the Center for Cognitive Neuroscience. (Except for a one-year sabbatical at the University of California, Santa Barbara in 1995-6.) As of 2008, he is the Johnstone Family Professor of Psychology at Harvard.
Pinker was named one of Time Magazine's 100 most influential people in the world in 2004 and one of Prospect and Foreign Policy's 100 top public intellectuals in 2005. He has also received honorary doctorates from the universities of Newcastle, Surrey, Tel Aviv, McGill, and the University of Tromsø, Norway. He was twice a finalist for the Pulitzer Prize, in 1998 and in 2003. In January 2005, Pinker defended Lawrence Summers, President of Harvard University, whose comments about the gender gap in mathematics and science angered much of the faculty. On May 13th 2006, Pinker received the American Humanist Association's Humanist of the Year award for his contributions to public understanding of human evolution.
In 2007, he was invited on The Colbert Report and asked under pressure to sum up how the brain works in five words – Pinker answered "Brain cells fire in patterns."
Pinker was born into the English-speaking Jewish community of Montreal. He has said, "I was never religious in the theological sense... I never outgrew my conversion to atheism at 13, but at various times was a serious cultural Jew." As a teenager, he says he considered himself an anarchist until he witnessed civil unrest following a police strike in 1969. His father, a trained lawyer, first worked as a traveling salesman, while his mother was first a home-maker then a guidance counselor and high-school vice-principal. He has two younger siblings. His brother is a policy analyst for the Canadian government. His sister, Susan Pinker, is a columnist for the Wall Street Journal and the author of The Sexual Paradox and The Village Effect.
Pinker married Nancy Etcoff in 1980 and they divorced 1992; he married Ilavenil Subbiah in 1995 and they too divorced. He is married to the novelist and philosopher Rebecca Goldstein, the author of 10 books and winner of the National Medal of the Humanities. He has no children.
His next book will take off from his research on "common knowledge" (knowing that everyone knows something). Its tentative title is: Don't Go There: Common Knowledge and the Science of Civility, Hypocrisy, Outrage, and Taboo.
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July 18, 2025
Although this is likely a lesser work in the Pinker Pantheon, When Everyone Knows That Everyone Knows... cleverly examines of the oft overlooked concept of common knowledge.
Pinker is quite precise about what "common knowledge" is, stating it's a collective epistemic state that results only when A knows X, B knows X, A knows that B knows X, B knows that A knows X, and so on ad infinitum. Pinker boldly claims that this recursive form of social knowledge is the linchpin behind coordination, cooperation, and collective action - otherwise known as the things that make humans human.
Pinker positions his claim as consistent but more foundational than Yuval Noah Harari's in Sapiens, which presents the more widely shared thesis that "our world is built on fictions" specifically the power of belief in various human narratives, including the state, private property, currency, individual rights, etc, is the X-factor that explains human success. The Pinker-cum-Harari thesis, itself narrative, is complemented by more rigorous and scientific theories of human success that are in circulation that still slot fairly neatly into the same paradigm: Acemoglu & Robinson's Why Nations Fail, The Social Brain by Robin Dunbar, and Joseph Henrich's The Secret of Our Successs, and The Theory of Everyone by Michael Muthukrishna. I raise these other works to highlight just how complicated the story of human success is; there isn't a single book or scientific study that's likely to perfectly explain why we've come to the spot we're in today. Pinker himself doesn't invest too much in this narrative in his book yet it is the rationale for why he's assembled a whole book on a seeming mundane idea.
Extending the justification for his interest in common knowledge, Pinker runs through a number of coordination problems that humans face. The examples he provides are typically abstracted, drawing heavily from economics and geopolitics, specifically the sub-field of game theory: the Prisoners' Dilemma, the Stag Hunt, the Battle of the Sexes, Hawks and Doves, etc. These coordination problems inevitably prompt questions about how to resolve them, which allows Pinker to explain the mechanism by which common knowledge can emerge: common salience (a focal point), conspicuity, and recursive mentalizing. Common knowledge doesn't necessarily lead to positive outcome though. Its presence can cause malign coordination as well as beneficial coordination, triggering a number of reciprocal strategies from various parties in a coordination game. Pinker walks through examples of this including bank runs, financial market bubbles, and Keynesian beauty contests.
After exploring the role of common knowledge in abstracted scenarios, Pinker shifts to a focus on social relationships (perhaps the most important human coordination problem), describing the structure of different types of relationships (communal sharing, authority ranking, equality matching, and market pricing - derived from Alan Fiske's work), the mechanisms involved (namely symbolic communication) and the stakes (reputation). This rolls into how our physiology is enmeshed in these dynamics, specifically how conspicuous emotional expressions that generate common knowledge (laughing, crying, blushing, staring, glaring). It also flows into strategies we've deployed to avoid acknowledging common knowledge, such as innuendo and euphemisms, or preclude its development, censorship, cancellation, and strategic hypocrisy. Intriguingly, Pinker invests the entire final chapter defending Plato's concept of the Noble Lie (without using that terminology), which in many ways is consistent with his belief in the power of common knowledge.
The book makes for compelling but sometimes laborious reading. The many examples require readers to trace recursive patterns of thought carefully instead of simply being able to chunk them. Pinker has to be this fastidious to make his points, but it isn't always easy on the reader. I also wish Pinker put more effort into demonstrating the claim that animates his interest in common knowledge - that it's foundational to human success because it is the basis for social conventions that power our modern world. A lot of this boils down to how language functions, but, surprisingly, Pinker spends little type focusing on spoken and written communication. Additionally, it is unclear how written language fits into the common knowledge model yet written language is almost certainly an important technology that catalyzed human development. It also side-steps the question of how non-human entities may share knowledge. Here, I'm of course thinking about the internet and now genAI chatbots. How can knowledge ever be carefully regulates when it's simply spilling out all over the place. Pinker avoid this dilemma yet the collapse of public-private knowledge and the degradation of common beliefs over the past few decades is arguably an important source of political polarization and dysfunction.
It also strains credulity to believe that recursive mentalization would be particularly important to sustain functional equilibria in various social games. This seems too tenuous. Of course, there is plenty of conflict, but common knowledge itself doesn't preclude conflict (it may provoke it) so it isn't clear that Pinker has really shown that common knowledge is essential. Nonetheless, he has helpfully re-direct my attention to the important of social epistemic.
Ultimately, Pinker's latest book is a really interesting exploration of the dynamics of social knowledge that are largely overlooked in day-to-day life. Plus, it covers a lot of Thomas Schelling's work, which has been incredibly influential but has not always been given its due. If you're a Pinker fan or simply interested in unseen dynamics of social life, then I recommend it.
Extended Review at Substack: Reading the Mind of the Mind Reader
Disclaimer: I received this as an ARC through Netgalley in exchange for an honest review.
Pinker is quite precise about what "common knowledge" is, stating it's a collective epistemic state that results only when A knows X, B knows X, A knows that B knows X, B knows that A knows X, and so on ad infinitum. Pinker boldly claims that this recursive form of social knowledge is the linchpin behind coordination, cooperation, and collective action - otherwise known as the things that make humans human.
Pinker positions his claim as consistent but more foundational than Yuval Noah Harari's in Sapiens, which presents the more widely shared thesis that "our world is built on fictions" specifically the power of belief in various human narratives, including the state, private property, currency, individual rights, etc, is the X-factor that explains human success. The Pinker-cum-Harari thesis, itself narrative, is complemented by more rigorous and scientific theories of human success that are in circulation that still slot fairly neatly into the same paradigm: Acemoglu & Robinson's Why Nations Fail, The Social Brain by Robin Dunbar, and Joseph Henrich's The Secret of Our Successs, and The Theory of Everyone by Michael Muthukrishna. I raise these other works to highlight just how complicated the story of human success is; there isn't a single book or scientific study that's likely to perfectly explain why we've come to the spot we're in today. Pinker himself doesn't invest too much in this narrative in his book yet it is the rationale for why he's assembled a whole book on a seeming mundane idea.
Extending the justification for his interest in common knowledge, Pinker runs through a number of coordination problems that humans face. The examples he provides are typically abstracted, drawing heavily from economics and geopolitics, specifically the sub-field of game theory: the Prisoners' Dilemma, the Stag Hunt, the Battle of the Sexes, Hawks and Doves, etc. These coordination problems inevitably prompt questions about how to resolve them, which allows Pinker to explain the mechanism by which common knowledge can emerge: common salience (a focal point), conspicuity, and recursive mentalizing. Common knowledge doesn't necessarily lead to positive outcome though. Its presence can cause malign coordination as well as beneficial coordination, triggering a number of reciprocal strategies from various parties in a coordination game. Pinker walks through examples of this including bank runs, financial market bubbles, and Keynesian beauty contests.
After exploring the role of common knowledge in abstracted scenarios, Pinker shifts to a focus on social relationships (perhaps the most important human coordination problem), describing the structure of different types of relationships (communal sharing, authority ranking, equality matching, and market pricing - derived from Alan Fiske's work), the mechanisms involved (namely symbolic communication) and the stakes (reputation). This rolls into how our physiology is enmeshed in these dynamics, specifically how conspicuous emotional expressions that generate common knowledge (laughing, crying, blushing, staring, glaring). It also flows into strategies we've deployed to avoid acknowledging common knowledge, such as innuendo and euphemisms, or preclude its development, censorship, cancellation, and strategic hypocrisy. Intriguingly, Pinker invests the entire final chapter defending Plato's concept of the Noble Lie (without using that terminology), which in many ways is consistent with his belief in the power of common knowledge.
The book makes for compelling but sometimes laborious reading. The many examples require readers to trace recursive patterns of thought carefully instead of simply being able to chunk them. Pinker has to be this fastidious to make his points, but it isn't always easy on the reader. I also wish Pinker put more effort into demonstrating the claim that animates his interest in common knowledge - that it's foundational to human success because it is the basis for social conventions that power our modern world. A lot of this boils down to how language functions, but, surprisingly, Pinker spends little type focusing on spoken and written communication. Additionally, it is unclear how written language fits into the common knowledge model yet written language is almost certainly an important technology that catalyzed human development. It also side-steps the question of how non-human entities may share knowledge. Here, I'm of course thinking about the internet and now genAI chatbots. How can knowledge ever be carefully regulates when it's simply spilling out all over the place. Pinker avoid this dilemma yet the collapse of public-private knowledge and the degradation of common beliefs over the past few decades is arguably an important source of political polarization and dysfunction.
It also strains credulity to believe that recursive mentalization would be particularly important to sustain functional equilibria in various social games. This seems too tenuous. Of course, there is plenty of conflict, but common knowledge itself doesn't preclude conflict (it may provoke it) so it isn't clear that Pinker has really shown that common knowledge is essential. Nonetheless, he has helpfully re-direct my attention to the important of social epistemic.
Ultimately, Pinker's latest book is a really interesting exploration of the dynamics of social knowledge that are largely overlooked in day-to-day life. Plus, it covers a lot of Thomas Schelling's work, which has been incredibly influential but has not always been given its due. If you're a Pinker fan or simply interested in unseen dynamics of social life, then I recommend it.
Extended Review at Substack: Reading the Mind of the Mind Reader
Disclaimer: I received this as an ARC through Netgalley in exchange for an honest review.
October 16, 2025
I've really enjoyed the other Pinker books I've read but this book was straight up white noise. Either I got dumber (possible) or there is just no central thesis to this book at all, it's just a series of anecdotes and vague points that add up to nothing. This book is like the over explained version of that episode of Friends where everyone keeps telling Joey "but they don't KNOW that we KNOW they KNOW we KNOW...!" complete with literally explaining that episode of Friends as an example of common knowledge. This one needed more time in the oven.
November 12, 2025
Fascinating, Thoughtful, and Surprisingly Human
As both a mom and a nurse, I’m used to reading people; their moods, their unspoken worries, the things they don’t say out loud. Stephen Pinker’s When Everyone Knows That Everyone Knows put all of that intuition into words. It’s a brilliant and deeply insightful look at how we understand what others are thinking, and how that shared awareness shapes everything from family life to world politics.
Pinker calls it common knowledge. It is what everyone knows and knows that everyone else knows. He explains how this idea quietly drives so much of human behavior: why we coordinate so naturally (like agreeing to drive on the right side of the road), why we sometimes pretend not to notice what’s obvious, and why honesty, though important, can sometimes make life unbearable.
I loved how he connected big global issues like financial bubbles, political movements, even social media shaming, and with small, everyday moments that any parent or caregiver will recognize: the delicate dance of communication, the instinct to protect feelings, the awkwardness of saying goodbye, or pretending not to see the “elephant in the room.”
It’s one of those books that changes how you see the world, and how you see the people right in front of you.
As both a mom and a nurse, I’m used to reading people; their moods, their unspoken worries, the things they don’t say out loud. Stephen Pinker’s When Everyone Knows That Everyone Knows put all of that intuition into words. It’s a brilliant and deeply insightful look at how we understand what others are thinking, and how that shared awareness shapes everything from family life to world politics.
Pinker calls it common knowledge. It is what everyone knows and knows that everyone else knows. He explains how this idea quietly drives so much of human behavior: why we coordinate so naturally (like agreeing to drive on the right side of the road), why we sometimes pretend not to notice what’s obvious, and why honesty, though important, can sometimes make life unbearable.
I loved how he connected big global issues like financial bubbles, political movements, even social media shaming, and with small, everyday moments that any parent or caregiver will recognize: the delicate dance of communication, the instinct to protect feelings, the awkwardness of saying goodbye, or pretending not to see the “elephant in the room.”
It’s one of those books that changes how you see the world, and how you see the people right in front of you.
November 12, 2025
This would be a great topic for a few chapters, I’m not sure it merited a whole book. A lot of interesting stuff, but some of it was eye-glazing. “He knows that she knows that he knows that she…” and “everyone knows but not everyone realizes that everyone else knows” are important concepts but I think a lot of the examples just go overboard.
I’m giving this book 4 stars because I just like reading Pinker too much to give it 3, but if there were half-stars available I’d probably do 3.5.
I’m giving this book 4 stars because I just like reading Pinker too much to give it 3, but if there were half-stars available I’d probably do 3.5.
October 3, 2025
This is another brilliant Steven Pinker book. It is full of insights, logic, intelligent observations, as well as a little bit of clever humor. Here, Pinker examines common knoladge. The title of the book explains what that term means. The book illuminates just how important that this concept is. Common knowledge is examined from multiple angles. The psychology underlying it, its sociology, its effects on individuals and society, as well as other aspects are explored. The book also includes lots of descriptions of logic games, puzzles as well as personal anecdotes. The author tries to illustrate just how important common knowledge is to humanity.
I have read multiple books by Pinker, and I think that he is one of the world’s greatest intellects. I believe that his books are instrumental in understanding the world and I recommend them all the time. Thus, I went into this expecting a lot. I mostly was not disappointed.
With all that, as several other reviewers have pointed out, this is not most important topic that the author has focused on. In addition, while the book was at times fascinating, it was occasionally a bit dull. As Pinker explained some of the psychological theories involving common knowledge, things became tedious.
I would recamend this book. Though this probably would not be the first Pinker work that I would read. But for those who appreciate the author’s other works, or who are particularly interested in the subjects covered, this is a worthwhile read.
I have read multiple books by Pinker, and I think that he is one of the world’s greatest intellects. I believe that his books are instrumental in understanding the world and I recommend them all the time. Thus, I went into this expecting a lot. I mostly was not disappointed.
With all that, as several other reviewers have pointed out, this is not most important topic that the author has focused on. In addition, while the book was at times fascinating, it was occasionally a bit dull. As Pinker explained some of the psychological theories involving common knowledge, things became tedious.
I would recamend this book. Though this probably would not be the first Pinker work that I would read. But for those who appreciate the author’s other works, or who are particularly interested in the subjects covered, this is a worthwhile read.
June 29, 2025
Оценка 3.5/5
Това е първата ми среща с книгите на Стивън Пинкър. В нея той разглежда понятието "обща култура" не в традиционния смисъл (знания по различни теми), а като споделено разбиране на дадена ситуация – аз виждам, че ти виждаш нещо, и ти осъзнаваш, че аз съм наясно с това, което ти виждаш, и така нататък. Тази идея е илюстрирана с множество примери от различни аспекти на ежедневието.
Това е първата ми среща с книгите на Стивън Пинкър. В нея той разглежда понятието "обща култура" не в традиционния смисъл (знания по различни теми), а като споделено разбиране на дадена ситуация – аз виждам, че ти виждаш нещо, и ти осъзнаваш, че аз съм наясно с това, което ти виждаш, и така нататък. Тази идея е илюстрирана с множество примери от различни аспекти на ежедневието.
August 2, 2025
Thinking about what other people think
I discovered Steve Pinker’s books a number of years ago via his wonderful description of the psychology of language in The Language Instinct and have enjoyed his discussions of how we think in many aspects of our lives in a number of his other books. When Everyone Knows That Everyone Knows… explores not just what we think but also what we think other people think and the effects of that thinking on our lives. Let me warn you---this book takes some thinking!
The first chapter gives an in-depth discussion of common knowledge, not only do I know it and you know it but I know you know it and vice versa, with the goal of showing how the concept illuminates many enigmas of our public affairs and personal lives. Each succeeding chapter explores common knowledge in some aspect of our lives and society.
The topics treated varied significantly, but they were all thought-provoking. From a pure enjoyment perspective, my favorite was probably Fun and Games, an area where what I think you think and vice versa can be crucial. Laughing, Crying, Blushing, Staring, Glaring looks at our emotional expressions as generators of common knowledge. My favorite chapters were probably the concluding ones, on The Canceling Instinct, the urge to prevent ideas from becoming common knowledge, and Radical Honesty, Rational Hypocrisy, on why not everything should be common knowledge. This would be a good book to read a chapter at a time, to give you a chance to ponder the ideas and also to give your brain a bit of a break!
Not surprisingly, Pinker cites a number of other thinkers, such as Yuval Harari, Robert Aumann, and Charles Darwin, and even quotes Mark Twain.
Lest the playful title mislead you, this book is not a quick read! The ideas are very thought-provoking and caused me to stop and ponder a number of times. On the down side, though, the style was rather academic, and some terms could have been better defined or clearer, but he carefully defined some terms that I would expect any reader of this book to know.
Overall, this is not a book to sit down with for a relaxed and quiet evening, but it is a good choice if you are looking for a book that will make you think, even if it is thinking about what other people think.
I received an advance review copy of this book from Edelweiss and Simon and Schuster.
I discovered Steve Pinker’s books a number of years ago via his wonderful description of the psychology of language in The Language Instinct and have enjoyed his discussions of how we think in many aspects of our lives in a number of his other books. When Everyone Knows That Everyone Knows… explores not just what we think but also what we think other people think and the effects of that thinking on our lives. Let me warn you---this book takes some thinking!
The first chapter gives an in-depth discussion of common knowledge, not only do I know it and you know it but I know you know it and vice versa, with the goal of showing how the concept illuminates many enigmas of our public affairs and personal lives. Each succeeding chapter explores common knowledge in some aspect of our lives and society.
The topics treated varied significantly, but they were all thought-provoking. From a pure enjoyment perspective, my favorite was probably Fun and Games, an area where what I think you think and vice versa can be crucial. Laughing, Crying, Blushing, Staring, Glaring looks at our emotional expressions as generators of common knowledge. My favorite chapters were probably the concluding ones, on The Canceling Instinct, the urge to prevent ideas from becoming common knowledge, and Radical Honesty, Rational Hypocrisy, on why not everything should be common knowledge. This would be a good book to read a chapter at a time, to give you a chance to ponder the ideas and also to give your brain a bit of a break!
Not surprisingly, Pinker cites a number of other thinkers, such as Yuval Harari, Robert Aumann, and Charles Darwin, and even quotes Mark Twain.
Lest the playful title mislead you, this book is not a quick read! The ideas are very thought-provoking and caused me to stop and ponder a number of times. On the down side, though, the style was rather academic, and some terms could have been better defined or clearer, but he carefully defined some terms that I would expect any reader of this book to know.
Overall, this is not a book to sit down with for a relaxed and quiet evening, but it is a good choice if you are looking for a book that will make you think, even if it is thinking about what other people think.
I received an advance review copy of this book from Edelweiss and Simon and Schuster.
October 2, 2025
This could be such a hit, if Pinker had taken his conclusions just one step further. He solidly lays out really relevant theories of group dynamics and game theory (now much more elaborate than the early days of morally dubious 1970s psychological experiments) and then almost applies them to the internet and social media. For instance, he can explain recursive mentalising (I know you know I know…ad inf.) and common knowledge (we all know = fame or shame) and has a short chapter at the end musing on the current acceleration to utter transparency, but the reasons why we have to stop short, why privacy is not just a good thing (for those who can afford it) but essential for the properly functioning society, there he just stops. It’s a shame because it really doesn’t take much knowledge of social media to apply the rules (lacking eye contact or sight of the poster, we reach for extra clues in the comments and can easily over-do the laugh, cry, blush, shrug or glare that would temper our verbal utterances). But he doesn’t go there and the book would be much more interesting if he did.
Always with legacy authors who have stuck their necks out (thinking of Richard Dawkins here) Pinker looks at the modern Western world and has a view. Here he tries carefully to paint both sides of the argument and does pretty well, for instance exploring freedom of speech at his institution, Harvard.
One area Pinker really could improve however is his experiment with innuendo. It would be fascinating to see how many of the participants were women, indeed how the results were collated and analysed (by men and/or women?), because the conclusion was that everyone prefers innuendo to bald statements, as a (sexual) refusal can then be shrugged off and the relationship resumed (still friends). The implications for rape cases - I thought she said yes, or at least she didn’t say no - are utterly absent here and women, who stand to benefit from plain speaking, are not reported separately here.
A useful read but not as much fun as it could be.
Always with legacy authors who have stuck their necks out (thinking of Richard Dawkins here) Pinker looks at the modern Western world and has a view. Here he tries carefully to paint both sides of the argument and does pretty well, for instance exploring freedom of speech at his institution, Harvard.
One area Pinker really could improve however is his experiment with innuendo. It would be fascinating to see how many of the participants were women, indeed how the results were collated and analysed (by men and/or women?), because the conclusion was that everyone prefers innuendo to bald statements, as a (sexual) refusal can then be shrugged off and the relationship resumed (still friends). The implications for rape cases - I thought she said yes, or at least she didn’t say no - are utterly absent here and women, who stand to benefit from plain speaking, are not reported separately here.
A useful read but not as much fun as it could be.
October 11, 2025
Another hit by Steven Pinker. The concept took a bit to wrap my head around but once I did it was evident that it had serious implications. Humans sure are complicated! Sometimes I wonder if I am a bit broken because I don't navigate the nuanced world of layers of pretending, but I suppose we all do to some extent. Worth reading, as is everything by Steven Pinker that I've read.
partiallyread
September 25, 2025I won this book in a Goodreads giveaway. I had read a few of Steven Pinker's books back when he was still writing about his area of expertise (language) and thought they were great. I remained aware of him and his assorted forays into wider territory but never actually read anything, but this seemed like it could potentially cover a lot of interesting ground, so I was happy to win the giveaway. Unfortunately, it just doesn't seem sufficient to write a book around. Sure, the concept of common knowledge can touch on a lot of interesting phenomena, but overall it just didn't seem like there was much to the book but a series of things, that didn't feel particularly in depth or edifying and after wading through a few chapters waiting for it to get somewhere, I just gave up on it as not particularly worth my time.
October 21, 2025
An above-average edition of Reader's Digest.
Notes
Our world is built on conventions that allow us to coordinate effectively and are self-reinforcing because of common knowledge.
Goods consumed in public more likely to be advertised during Superbowl than consumed in private. Depends on everyone knowing that everyone knows.
Communities have an incentive to enforce norms by publicly punishing flouters so the common knowledge assures that the norms still hold.
Convention is more efficient than courtesy when it comes to coordination, so we create common knowledge generators like zebra-crossings and traffic lights.
Rousseau’s Stag Hunt: every hunter is tempted by selfishness/impatience to pursue the small but sure reward of a hare over a larger less certain reward of the stag for which his fellow hunters depend on his cooperation. Bank runs are Stag Hunts, everyone must have confidence that everyone else has confidence and noone seeks to withdraw (federal deposit insurance).
Piaget’s Concrete Operations stage of cognitive development, or Age of Reason, when children understand 2nd order mentalizing (I know that John thinks that Mary thinks X). Adults test drops off a cliff at 5th order, so maybe we have 4 slots - better for people with better working memory, language skill, and lower autism.
Laughter generates common knowledge of an indignity that undermines a claim to dominance/status to be used aggressively (challenge a dominant figure) or convivially (signal that dominant-subordinate does not apply).
Darwin’s ‘antithesis’ - animal in a state opposite to one that triggers a certain posture, produces the physically opposite posture: dog in attack-mode is stiff body, rigid tail, teeth bared vs friendly mode - wagging tail, wriggling body, slack ears/lips. Human laughter (long inhale, short ha ha exhales, muscles contract) vs crying (short deep gasp inhales, long sigh exhale, body slumps)
Two of three negative self-conscious emotions (embarrassment, shame) trigger blushing, but not the third (guilt). Blush when accused even when innocent, that others think I’m guilty causes it. Embarrassment is public breach of social norm vs Shame is public breach of moral norm. Blushing functions as nonverbal apology.
Eye contact is the ultimate common knowledge generator - we are seeing the part of the person that sees us see them see us.
Notes
Our world is built on conventions that allow us to coordinate effectively and are self-reinforcing because of common knowledge.
Goods consumed in public more likely to be advertised during Superbowl than consumed in private. Depends on everyone knowing that everyone knows.
Communities have an incentive to enforce norms by publicly punishing flouters so the common knowledge assures that the norms still hold.
Convention is more efficient than courtesy when it comes to coordination, so we create common knowledge generators like zebra-crossings and traffic lights.
Rousseau’s Stag Hunt: every hunter is tempted by selfishness/impatience to pursue the small but sure reward of a hare over a larger less certain reward of the stag for which his fellow hunters depend on his cooperation. Bank runs are Stag Hunts, everyone must have confidence that everyone else has confidence and noone seeks to withdraw (federal deposit insurance).
Piaget’s Concrete Operations stage of cognitive development, or Age of Reason, when children understand 2nd order mentalizing (I know that John thinks that Mary thinks X). Adults test drops off a cliff at 5th order, so maybe we have 4 slots - better for people with better working memory, language skill, and lower autism.
Laughter generates common knowledge of an indignity that undermines a claim to dominance/status to be used aggressively (challenge a dominant figure) or convivially (signal that dominant-subordinate does not apply).
Darwin’s ‘antithesis’ - animal in a state opposite to one that triggers a certain posture, produces the physically opposite posture: dog in attack-mode is stiff body, rigid tail, teeth bared vs friendly mode - wagging tail, wriggling body, slack ears/lips. Human laughter (long inhale, short ha ha exhales, muscles contract) vs crying (short deep gasp inhales, long sigh exhale, body slumps)
Two of three negative self-conscious emotions (embarrassment, shame) trigger blushing, but not the third (guilt). Blush when accused even when innocent, that others think I’m guilty causes it. Embarrassment is public breach of social norm vs Shame is public breach of moral norm. Blushing functions as nonverbal apology.
Eye contact is the ultimate common knowledge generator - we are seeing the part of the person that sees us see them see us.
October 7, 2025
I’ll be honest: I would’ve enjoyed this book far more had I started with Chapter 8. If it were going on my shelf, I’d probably staple the first seven chapters together—not because they’re terrible, but because they’re painfully repetitive, redundant. Pinker spends hundreds of pages proving, via endless game-theory experiments, that “common knowledge” is the social glue that makes coordination, trust, and cooperation possible.
We get it. Everyone knows what everyone knows. And by Chapter 6, everyone knows they know that.
But then came Chapter 8, where the abstract finally collides with the real world—specifically, the messy cultural experiment of cancel culture. Here, Pinker stops diagramming thought bubbles and starts dissecting a social pathology. He explains that when knowledge of a moral rule becomes publicly shared and publicly monitored, people enforce it performatively. Not because they believe it, but because they know everyone else knows they’re supposed to and lying to ourselves feels better than being on the outside of the hive.
Cancel culture is more than deplatforming outrage—it’s a self-reinforcing system of conforming stupidity. Once an accusation becomes common knowledge, in spite of how ridiculous it is, the social cost of dissent skyrockets and we all turn into lemmings. People virtue signal to avoid being the next target, and the cycle feeds itself and the cancer grows. “Maoist incentive structure” of modern life: moral purity achieved through public denunciation.
Common knowledge is gasoline for social punishment. Everyone joins the mob, even if no one actually believes the slogans. In hindsight all we could ever be is a digital Red Guard—feeling righteous and vindicated through synchronized hate. And Pinker, to his credit, doesn’t just wag his finger from a distance. He sounds genuinely embarrassed to belong to the academic establishment that fuels this hysteria.
By the end of the chapter, you can feel his exasperation: a lifelong rationalist watching reason devour itself. When everyone knows what everyone knows but what everyone knows is hollow, courage evaporates, truth bends, and wisdom slips quietly out the back door.
The rest of the book is ok but Chapter 8? That’s Pinker with his sleeves rolled up, finally admitting that ivory towers of coercion through common knowledge at the expense of sanity is dumb. Dumb dumb dumb.
Loved it.
November 3, 2025
This book low-key ticked me off. It covered the exact same ground as every book over the past 20 years written by someone with the same game-theoretic/mind-is-a-computer perspective. Did it talk about the Prisoners Dilemma? Oh, absolutely, over and over, again and again. What about the Ultimatum game, what about Milgram’s experiments, and Nash equilibrium, and Bayes’s? yes, yes, yes, and yes. The same old stuff recycled into this ludicrous tedium of infinitely recursive recognition hinted at by the equally ludicrous title.
I can see that the author felt this a vital time to publish another book because he believes his approach can heal the political divide, but no one need read it if they’ve read anything in the field since 1990.
The book wasn’t informative nor actionable, but all the cartoons and anecdotes at least made it relatively amusing.
I can see that the author felt this a vital time to publish another book because he believes his approach can heal the political divide, but no one need read it if they’ve read anything in the field since 1990.
The book wasn’t informative nor actionable, but all the cartoons and anecdotes at least made it relatively amusing.
October 5, 2025
Huge Pinker fan and Better Angels should be required reading for all the “sky is falling” crowd that is panicking about the state of the word in every generation (not that it will make a difference, but maybe for 1 in 500 it will). This book, however, is impenetrable or at least beyond me, felt unnecessarily long, with few to zero practical tips beyond noting that we are generally poor rational thinkers.
October 3, 2025
Typical Pinker, know what I mean? Nudge nudge, wink wink. No? Well, let me be clear then. When Everyone Knows That Everyone Knows is filled with the typical deep insights into human psychology, beautiful prose, and sharp wit that Pinker is known for.
October 13, 2025
Pinker takes the concept of common knowledge (not just shared, public information, but (per the ellipsis in the title) things that I know, and you know that I know, and I know that you know that I know, and you know that I know that you know that I know...) and uses it to explain how society works. The book is a clear explanation of why we behave the way we do and why we say what we do, through the lens of "recursive mentalizing." In the last two chapters, Pinker also covers when and why we avoid common knowledge, addressing cancel culture and hypocrisy. Caveat lector, it's a book by Steven Pinker so you'll probably have to stop and look up some words. But it's worth it.
October 3, 2025
It's okay and definitely made me think. Listening to the audiobook made me purchase the hardcover so that I could follow the arguments better (she knows that he knows that she knows...), but I felt it lost steam.
September 22, 2025
I received this ARC from the Goodreads Giveaway 8/23/2025. I have done my best, read 1/3 of this book , could not complete it. Don't know if the book is good or bad, it just never captured my interest. The experience was like searching for water in the Sahara, dry, dry dry.
June 24, 2025
"When Everyone Knows That Everyone Knows" is Steven Pinker's worst book, but it's still fascinating, especially if you're into logic and puzzles.
Disclosure: I've read all of Pinker's books, and I gave them all five stars. I graduated from Harvard, where Pinker teaches. I received a free advanced copy of Everyone Knows That Everyone Knows from the publisher. None of these factors biases my judgment: I give this book 3.5 stars.
When Everyone Knows That Everyone Knows is about common knowledge.
What is common knowledge?
Other terms for common knowledge include open knowledge, conspicuous knowledge, public knowledge, interactive knowledge, shared reality, shared awareness, collective consciousness, and common ground.
Why is common knowledge important?
Many of our tensions, personal and political, arise from the desire to propagate or suppress common knowledge.
What answers does Pinker's book answer?
Pinker's book answers questions like:
Why do people hoard toilet paper at the first sign of an emergency?
Why are Super Bowl ads filled with ads for crypto?
Why, in American presidential primary voting, do citizens typically select the candidate they believe is preferred by others rather than their favorite?
Why did Russian authorities arrest a protester who carried a blank sign?
Why is it so hard for nervous lovers to say goodbye at the end of a phone call?
Why does everyone agree that if we were completely honest all the time, life would be unbearable?
Where Pinker disagrees with Yuval Harari
Yuval Harari and Stephen Pinker are among my top 3 authors (I also love Bill Bryson). Therefore, my ears paid attention when Pinker disagreed with a minor point Harari made about humans creating fictions. I quoted one of those fictions when I explained in my article, "Why is Bitcoin Worth Anything?"
Pinker says Harari is too extreme when he categorizes many human inventions as "fictions." Pinker partially agrees, but points out a nuance:
Our world is built on conventions that allow us to coordinate effectively and are self-reinforcing because they are common knowledge. Conventions like the English language, Christianity, the United States of America, the euro, and Microsoft are not exactly “fictions.” They are very real, even if they are not made out of physical stuff. Common knowledge creates nonphysical realities.
If you have long wondered why people often don’t say what they mean in so many words but veil their intentions in innuendo and doublespeak, counting on their listeners to read between the lines, then this is your book.
Funny story
As usual, Pinker litters his book with humor, including comic strips. One of my favorite parts is when he tells this joke:
A defendant was on trial for murder. There was strong evidence indicating his guilt, but there was no corpse. In his closing statement, the defense attorney resorted to a trick.
“Ladies and gentlemen of the jury,” he said. “I have a surprise for you all—within one minute, the person presumed dead will walk into this courtroom.”
He looked toward the courtroom door. The jurors, stunned, all looked eagerly.
A minute passed.
Nothing happened.
Finally the lawyer said, “Actually, I made up the business about the dead man walking in. But you all looked at the door with anticipation. I therefore put it to you that there is reasonable doubt in this case as to whether anyone was killed, and I must insist that you return a verdict of ‘not guilty.’”
The jury retired to deliberate.
A few minutes later, they returned and pronounced a verdict of “guilty.”
“But how could you do that?” bellowed the lawyer. “You must have had some doubt. I saw all of you stare at the door.”
The jury foreman replied, “Oh, we looked, but your client didn’t.”
Social paradox
I learned about a social paradox, a term suggested by the psychologist David Pinsof for phenomena like these:
1. We try to gain status by not caring about status.
2. We rebel against conformity in the same way as everyone else.
3. We show humility to prove we’re better than other people.
4. We don’t care what people think, and we want them to think this.
5. We make anonymous donations to get credit for not caring about getting credit.
6. We bravely defy social norms so that people will praise us.
7. We avoid being manipulative to get people to do what we want them to do.
8. We compete to be less competitive than our rivals.
9. We help those in need, regardless of self-interest, because being seen as the type of person who helps those in need, regardless of self-interest, is in our self-interest.
10. We make subversive art that only high-status people appreciate.
11. We make fun of ourselves for being uncool to prove we’re cool.
12. We self-righteously defend false beliefs to prove we care more about the truth than virtue-signaling.
13. We help our friends without expecting anything in return, because we know they would do the same for us.
14. We show everyone our true, authentic self—not who society wants us to be—because that is who society wants us to be.
Chapter against wokeism
One of the things I admire most about Pinker is that he's a moderate, unlike most of the leftists at Harvard. Pinker spends a chapter destroying the woke ideology and the cancel culture, which is contrary to the open discourse that universities must have.
Conclusion
With so many good passages, why only 3.5 stars? It's because the first 100 pages are filled with tedious logic exercises that disinterested me. In all the other Pinker books, I savor every word. In When Everyone Knows That Everyone Knows, I skipped pages, exhausted by Pinker's nonstop discussion about how John knows what Sally thinks about John knowing about Sally's kid (and far more layered than that!). My eyes rolled.
Still, When Everyone Knows That Everyone Knows is another worthwhile book, even if it's Pinker's worst. Pinker's worst is among the top 1% of all nonfiction books of 2025.
Disclosure: I've read all of Pinker's books, and I gave them all five stars. I graduated from Harvard, where Pinker teaches. I received a free advanced copy of Everyone Knows That Everyone Knows from the publisher. None of these factors biases my judgment: I give this book 3.5 stars.
When Everyone Knows That Everyone Knows is about common knowledge.
What is common knowledge?
Other terms for common knowledge include open knowledge, conspicuous knowledge, public knowledge, interactive knowledge, shared reality, shared awareness, collective consciousness, and common ground.
Why is common knowledge important?
Many of our tensions, personal and political, arise from the desire to propagate or suppress common knowledge.
What answers does Pinker's book answer?
Pinker's book answers questions like:
Why do people hoard toilet paper at the first sign of an emergency?
Why are Super Bowl ads filled with ads for crypto?
Why, in American presidential primary voting, do citizens typically select the candidate they believe is preferred by others rather than their favorite?
Why did Russian authorities arrest a protester who carried a blank sign?
Why is it so hard for nervous lovers to say goodbye at the end of a phone call?
Why does everyone agree that if we were completely honest all the time, life would be unbearable?
Where Pinker disagrees with Yuval Harari
Yuval Harari and Stephen Pinker are among my top 3 authors (I also love Bill Bryson). Therefore, my ears paid attention when Pinker disagreed with a minor point Harari made about humans creating fictions. I quoted one of those fictions when I explained in my article, "Why is Bitcoin Worth Anything?"
Pinker says Harari is too extreme when he categorizes many human inventions as "fictions." Pinker partially agrees, but points out a nuance:
Our world is built on conventions that allow us to coordinate effectively and are self-reinforcing because they are common knowledge. Conventions like the English language, Christianity, the United States of America, the euro, and Microsoft are not exactly “fictions.” They are very real, even if they are not made out of physical stuff. Common knowledge creates nonphysical realities.
If you have long wondered why people often don’t say what they mean in so many words but veil their intentions in innuendo and doublespeak, counting on their listeners to read between the lines, then this is your book.
Funny story
As usual, Pinker litters his book with humor, including comic strips. One of my favorite parts is when he tells this joke:
A defendant was on trial for murder. There was strong evidence indicating his guilt, but there was no corpse. In his closing statement, the defense attorney resorted to a trick.
“Ladies and gentlemen of the jury,” he said. “I have a surprise for you all—within one minute, the person presumed dead will walk into this courtroom.”
He looked toward the courtroom door. The jurors, stunned, all looked eagerly.
A minute passed.
Nothing happened.
Finally the lawyer said, “Actually, I made up the business about the dead man walking in. But you all looked at the door with anticipation. I therefore put it to you that there is reasonable doubt in this case as to whether anyone was killed, and I must insist that you return a verdict of ‘not guilty.’”
The jury retired to deliberate.
A few minutes later, they returned and pronounced a verdict of “guilty.”
“But how could you do that?” bellowed the lawyer. “You must have had some doubt. I saw all of you stare at the door.”
The jury foreman replied, “Oh, we looked, but your client didn’t.”
Social paradox
I learned about a social paradox, a term suggested by the psychologist David Pinsof for phenomena like these:
1. We try to gain status by not caring about status.
2. We rebel against conformity in the same way as everyone else.
3. We show humility to prove we’re better than other people.
4. We don’t care what people think, and we want them to think this.
5. We make anonymous donations to get credit for not caring about getting credit.
6. We bravely defy social norms so that people will praise us.
7. We avoid being manipulative to get people to do what we want them to do.
8. We compete to be less competitive than our rivals.
9. We help those in need, regardless of self-interest, because being seen as the type of person who helps those in need, regardless of self-interest, is in our self-interest.
10. We make subversive art that only high-status people appreciate.
11. We make fun of ourselves for being uncool to prove we’re cool.
12. We self-righteously defend false beliefs to prove we care more about the truth than virtue-signaling.
13. We help our friends without expecting anything in return, because we know they would do the same for us.
14. We show everyone our true, authentic self—not who society wants us to be—because that is who society wants us to be.
Chapter against wokeism
One of the things I admire most about Pinker is that he's a moderate, unlike most of the leftists at Harvard. Pinker spends a chapter destroying the woke ideology and the cancel culture, which is contrary to the open discourse that universities must have.
Conclusion
With so many good passages, why only 3.5 stars? It's because the first 100 pages are filled with tedious logic exercises that disinterested me. In all the other Pinker books, I savor every word. In When Everyone Knows That Everyone Knows, I skipped pages, exhausted by Pinker's nonstop discussion about how John knows what Sally thinks about John knowing about Sally's kid (and far more layered than that!). My eyes rolled.
Still, When Everyone Knows That Everyone Knows is another worthwhile book, even if it's Pinker's worst. Pinker's worst is among the top 1% of all nonfiction books of 2025.
November 22, 2025
Approaching When Everyone Knows That Everyone Knows... creates a unique sense of anticipation; the recursive title implies a depth that could be taken in a dozen different directions. In truth, the author has embraced this ambiguity, delivering a work that feels less like a linear textbook and more like a curated collection of high-level essays. The connective tissue binding these chapters to the central concept of "common knowledge" is loose, which strangely works in the book’s favor, although this may not be to everyone’s liking. It moves beyond the popular narrative approach found in works like Harari’s Sapiens—which posits that fictions rule the world—and instead rigorously dismantles the machinery of those fictions, aka communication, which is neither simple nor given even when the knowledge to be transferred and at the root of subsequent actions has nothing private. The book is largely about communication issues, but with a series of pertinent anecdotes, the book is able to cover much more.
To repeat, the book lacks a core message. The consequent scattering of concepts might initially seem daunting to those expecting a standard pop-psychology formula, but patience here is richly rewarded. The book is dense with "aha moments," a rarity for readers already well-versed in behavioral science or game theory. The author consistently surprises by illustrating that common knowledge is not merely shared information but a specific "collective epistemic state" that serves as the linchpin of all human coordination. Early in the text, the author does an exceptional job of grounding abstract theory in cognitive reality. There is a profound exploration of the hard limits of communication theory—specifically the realization that in any attempt at coordination, it is theoretically impossible to fully confirm a message has been received and understood ad infinitum. The book goes on to brilliantly juxtapose this with our cognitive limitations regarding recursive thought; humans can rarely hold more than three or four layers of "I know that you know that I know." Both these concepts are rarely discussed in great detail in any popular behavioral books, but both are critically important once discussed for their implications in the book.
The middle sections serve as a bridge, utilizing established game theory concepts to explore the paradox of information. While these chapters can feel like "fillers" or distinct interludes, they are essential for deconstructing the assumption that information equality leads to predictable outcomes. By weaving in concepts of "focal points" and "salience," we are shown how we get solutions to coordination problems that result in episodes like coups or bank runs, or financial frenzies. These sections enrich the understanding by throwing light on knowledge transmission issues, demonstrating that perfect knowledge of another party's facts may still lead to little insight into their action sets without a shared focal point.
It is in the final chapters, however, that the book truly shines. The transition into the analysis of "oblique" and "polite" messaging is nothing short of a masterclass, despite numerous obvious points once the chapters’ intents became clear. Here, the abstract theories find their footing in the messy reality of human social interaction. The book dissects the utility of innuendo, euphemism, and "strategic hypocrisy," explaining why we often prefer not to create common knowledge. The sections that dissect how maintaining plausible deniability is not just about saving face, but about preserving the fragile social contract,s are perhaps the best parts.
Ultimately, the power of this book lies not in a single, overarching lesson, but in the richness of its granular details. For anyone looking to understand the subtle, invisible architecture of human communication, this is an illuminating read.
To repeat, the book lacks a core message. The consequent scattering of concepts might initially seem daunting to those expecting a standard pop-psychology formula, but patience here is richly rewarded. The book is dense with "aha moments," a rarity for readers already well-versed in behavioral science or game theory. The author consistently surprises by illustrating that common knowledge is not merely shared information but a specific "collective epistemic state" that serves as the linchpin of all human coordination. Early in the text, the author does an exceptional job of grounding abstract theory in cognitive reality. There is a profound exploration of the hard limits of communication theory—specifically the realization that in any attempt at coordination, it is theoretically impossible to fully confirm a message has been received and understood ad infinitum. The book goes on to brilliantly juxtapose this with our cognitive limitations regarding recursive thought; humans can rarely hold more than three or four layers of "I know that you know that I know." Both these concepts are rarely discussed in great detail in any popular behavioral books, but both are critically important once discussed for their implications in the book.
The middle sections serve as a bridge, utilizing established game theory concepts to explore the paradox of information. While these chapters can feel like "fillers" or distinct interludes, they are essential for deconstructing the assumption that information equality leads to predictable outcomes. By weaving in concepts of "focal points" and "salience," we are shown how we get solutions to coordination problems that result in episodes like coups or bank runs, or financial frenzies. These sections enrich the understanding by throwing light on knowledge transmission issues, demonstrating that perfect knowledge of another party's facts may still lead to little insight into their action sets without a shared focal point.
It is in the final chapters, however, that the book truly shines. The transition into the analysis of "oblique" and "polite" messaging is nothing short of a masterclass, despite numerous obvious points once the chapters’ intents became clear. Here, the abstract theories find their footing in the messy reality of human social interaction. The book dissects the utility of innuendo, euphemism, and "strategic hypocrisy," explaining why we often prefer not to create common knowledge. The sections that dissect how maintaining plausible deniability is not just about saving face, but about preserving the fragile social contract,s are perhaps the best parts.
Ultimately, the power of this book lies not in a single, overarching lesson, but in the richness of its granular details. For anyone looking to understand the subtle, invisible architecture of human communication, this is an illuminating read.
October 5, 2025
Thank you to Scribner for the ARC of this book via a Goodreads giveaway!
I've always been interested in language, human psychology, and the evolutionary underpinnings of and explanations for these emergent features, so I figured this book would be right up my alley. Yet I couldn't quite wrap my head around a lot of what was said. It's worth noting that that probably says more about my poor little brain being unable to grasp some of the concepts than it does about the concepts themselves. I believe I would have had a better chance at understanding more of the book had I read some of Pinker's previous works to better grasp his train of thought.
When Everyone Knows That Everyone Knows is a book that has a really interesting focal point: common knowledge. I think the best example of what common knowledge is was Pinker's reference to the toilet paper shortage a few years back. It wasn't just that people knew there might be a shortage due to the suggestion of such a possibility in the media, but that they also knew that everyone else knew that fact as well. And when everyone knows that everyone else knows about a shortage, there arises a need to act upon that information, thus the self-fulfilling prophecy of the shortage. You know that they know it. They know you know it. You know they know that you know they know it. They know you know that they know you know it? That's where I get lost and my brain just cant compute. This so-called "recursive mentalizing" just shuts of my capacity for any further thought.
To the extent that I can understand that people think about what other people think and that they think about what other people think they think, some of the implications mentioned are really compelling. An example similar to, but much more dire than the aforementioned TP situation, are bank runs. When people get the sense that a bank is about to become insolvent, everyone knows the implications - which isn't so bad on its own - but for the fact that everyone knows that everyone else knows the implications, which creates the urge in each individual to preempt all of the other possessors of this common knowledge by withdrawing their money from the bank. There are plenty of real-life applications behind the idea of common knowledge and the book covers far more than what I mention here.
On the off chance that anyone sees this review, don't let this dissuade you from picking up the book. There's a lot of value in it, I just struggled with the concept of this infinite recursive mentalizing, and no matter how much I reread certain passages, I just couldn't quite make the connection. That said, you might be able to make the logical leaps that I couldn't.
This could definitely be five stars if I understand it better when I reread it.
I've always been interested in language, human psychology, and the evolutionary underpinnings of and explanations for these emergent features, so I figured this book would be right up my alley. Yet I couldn't quite wrap my head around a lot of what was said. It's worth noting that that probably says more about my poor little brain being unable to grasp some of the concepts than it does about the concepts themselves. I believe I would have had a better chance at understanding more of the book had I read some of Pinker's previous works to better grasp his train of thought.
When Everyone Knows That Everyone Knows is a book that has a really interesting focal point: common knowledge. I think the best example of what common knowledge is was Pinker's reference to the toilet paper shortage a few years back. It wasn't just that people knew there might be a shortage due to the suggestion of such a possibility in the media, but that they also knew that everyone else knew that fact as well. And when everyone knows that everyone else knows about a shortage, there arises a need to act upon that information, thus the self-fulfilling prophecy of the shortage. You know that they know it. They know you know it. You know they know that you know they know it. They know you know that they know you know it? That's where I get lost and my brain just cant compute. This so-called "recursive mentalizing" just shuts of my capacity for any further thought.
To the extent that I can understand that people think about what other people think and that they think about what other people think they think, some of the implications mentioned are really compelling. An example similar to, but much more dire than the aforementioned TP situation, are bank runs. When people get the sense that a bank is about to become insolvent, everyone knows the implications - which isn't so bad on its own - but for the fact that everyone knows that everyone else knows the implications, which creates the urge in each individual to preempt all of the other possessors of this common knowledge by withdrawing their money from the bank. There are plenty of real-life applications behind the idea of common knowledge and the book covers far more than what I mention here.
On the off chance that anyone sees this review, don't let this dissuade you from picking up the book. There's a lot of value in it, I just struggled with the concept of this infinite recursive mentalizing, and no matter how much I reread certain passages, I just couldn't quite make the connection. That said, you might be able to make the logical leaps that I couldn't.
This could definitely be five stars if I understand it better when I reread it.
November 21, 2025
Steven Pinker’s When Everyone Knows That Everyone Knows starts out with the kind of clarity and charm that makes you think you have mastered the entire field of epistemology before your coffee even cools. The introduction is crisp, accessible, and delightfully free of any need to diagram sentences on a whiteboard. The conclusion, for its part, returns to this friendly tone and wraps everything up so clearly that you may briefly suspect you are some sort of latent genius who could have written the book yourself if only you had started just a little earlier. These are comforting illusions. Treasure them.
The middle of the book, however, is where Pinker politely but firmly closes the door, rolls up his sleeves, and proceeds to reenact his years in graduate school for you. The narrative shifts from broad, smooth general audience prose to an intellectual deep dive that feels like following an Olympic swimmer across the English Channel while you dog paddle heroically behind. The topic at hand is common knowledge, which is deceptively simple in the abstract. Pinker approaches it in a structured, logical, and entirely coherent way. The trouble is that logic, when delivered in large and concentrated quantities, has the unfortunate tendency to make even diligent readers gaze longingly at nearby windows.
This is not to say the book is dull. Pinker retains his trademark wit and precision. He organizes his argument as neatly as a mathematician lining up proofs, and the central thesis is supported throughout with admirable rigor. The problem is simply that rigor is more enjoyable in moderation. Pinker offers it to you in something closer to an academic buffet, complete with every related concept you never knew existed and may politely hope never to encounter again after finishing the chapter.
Still, the journey is worth it. If you commit to the middle sections and resist the urge to wander off in search of lighter reading, you end up with a much deeper appreciation of how humans build shared understanding. Pinker guides the reader from simple examples to complex implications, then back to broad conclusions in a satisfying loop. It is genuinely impressive how he keeps the material as engaging as possible given the intricacy of the logic processes he explores.
In the end, When Everyone Knows That Everyone Knows succeeds both as a thoughtful academic work and as an accessible introduction to a topic that influences everything from social norms to geopolitics. Just be prepared for the fact that the clarity at the beginning and end is your warm blanket, and the middle is your brisk intellectual cold shower. Pinker is a generous guide, but he does expect you to keep up.
The middle of the book, however, is where Pinker politely but firmly closes the door, rolls up his sleeves, and proceeds to reenact his years in graduate school for you. The narrative shifts from broad, smooth general audience prose to an intellectual deep dive that feels like following an Olympic swimmer across the English Channel while you dog paddle heroically behind. The topic at hand is common knowledge, which is deceptively simple in the abstract. Pinker approaches it in a structured, logical, and entirely coherent way. The trouble is that logic, when delivered in large and concentrated quantities, has the unfortunate tendency to make even diligent readers gaze longingly at nearby windows.
This is not to say the book is dull. Pinker retains his trademark wit and precision. He organizes his argument as neatly as a mathematician lining up proofs, and the central thesis is supported throughout with admirable rigor. The problem is simply that rigor is more enjoyable in moderation. Pinker offers it to you in something closer to an academic buffet, complete with every related concept you never knew existed and may politely hope never to encounter again after finishing the chapter.
Still, the journey is worth it. If you commit to the middle sections and resist the urge to wander off in search of lighter reading, you end up with a much deeper appreciation of how humans build shared understanding. Pinker guides the reader from simple examples to complex implications, then back to broad conclusions in a satisfying loop. It is genuinely impressive how he keeps the material as engaging as possible given the intricacy of the logic processes he explores.
In the end, When Everyone Knows That Everyone Knows succeeds both as a thoughtful academic work and as an accessible introduction to a topic that influences everything from social norms to geopolitics. Just be prepared for the fact that the clarity at the beginning and end is your warm blanket, and the middle is your brisk intellectual cold shower. Pinker is a generous guide, but he does expect you to keep up.
October 13, 2025
This new book from Steven Pinker concerns an area of his cognitive-science research. As sometimes happens, it has the feel of material he's previously tried out in a lecture hall on Harvard students. Down to occasional amusing cartoons, anecdotes, and examples taken from pop culture.
See the subtitle for his topic: "common knowledge". It's a bland descriptive term for something that might seem a little offbeat and specialized. He describes it upfront in his preface, first paragraph:
As a cognitive scientist, I have spent my life thinking about how people think. So the ultimate subject of my fascination would have to be how people think about what other people think, and how they think about what other people think they think, and how they think about what other people think they think they think. As dizzying as this cogitation may seem, we engage in it every day, at least tacitly, and in the limit this state of awareness has a technical name, common knowledge.
Reader, he's not kidding. "Common knowledge" is a real thing, and Pinker shows that once you start looking for it, you see it everywhere, and it explains a lot about our social interactions and thought processes. And note that the recursion implied in his description really is (conceptually) infinite ("turtles all the way down" occurs later in the book). Although our brains tend to peter out when trying to unwind more than a handful of levels.
The book gets into game theory pretty quickly; the famous Prisoner's Dilemma comes out to play as a simple example of thinking about what the other guy is thinking, who's thinking about what you're thinking he's thinking about, and …
Pinker reports on some of his own research, too. And it made me glad that I've never been asked to bend my brain in one of his experiments.
I'll report my slight disagreement on one matter: when discussing how we communicate knowledge non-verbally (and sometimes involutarily), via laughter, crying, blushing, and facial expressions, he states (p. 197): "People seldom laugh when they’re alone."
Wha? Steve, I'm (alas) alone most of the time these days, and I manage to laugh quite a bit!
To be fair, he mentions that solitary laughter will be "usually in the presence of virtual people": on the TV/computer screen or in reading material. OK, you somewhat saved yourself there, Steve.
So, bottom line: an unexpectedly illuminating topic, and Pinker does a fine job of demonstrating its ubiquity and usefulness. Things get slightly repetitive and hand-wavy in the final chapter, but that's OK.
October 19, 2025
For a 300 page book there was quite a bit of covering the same ground, which combined with the somewhat bare chapter on university cancel culture, gave the impression this had to have some filler to reach that page count. In previous books Pinker had set out everyday experience in more scientific terms, and while that was present to an extent, many sections seemed more guided by his own theory than rigourous evidence.
His book on violence was easy to read without being fun to read and this was similar, in that it was free of jargon but not hugely engaging. The central theme was the signficance of public knowledge, where information was made clear to everyone, and everyone was aware it was received by everyone. A lot of it dealt with hard logic and its impact on psychology, which unfortunately meant a lot of the logical steps had to be explained in detail, one of the ways in which my interest waned. Pinker posited that it affects many interactions, especially relating to status, and analysed the limits of our brains to interpret the iterations of "he believes that she believes that he believes x".
There were several times where everyday experiences were well-illustrated, such as single verbs like 'deceive' and 'bluff' making multi-layered relations easier to formulate in a single concept, or a scene from friends exploiting differences in knowledge. However there were also instances where Pinker was very ambitious in using this concept to explain crying, laughing and euphemism, and I thought crying and laughter required much more evidence to support his claims. These were quite theoretical, bordering on evolutionary psychology, and lacked rigour. Laughter is often employed as much to pick on the underdog as pierce the hierarchy, and this was acknowledged and dismissed almost instantly.
Euphemism was explained by plausible deniability in case of rebuff, especially in relation to dating. This didn't outline why it was used in other contexts however, such as death, which ambiguity is not desired. There was too little in terms of counterexamples as to why his theory was the only explanation rather than a possible explanation.
Overall this was a book that contained insights within it, rather than one that succinctly but elegantly covered the subject. Both the writing style and arguments contained within it could have been stronger, or in the case of university cancellation, much stronger - this seemed to be a vehicle to put his gripe on paper rather than adding to the scientific canon, even though I essentially agreed with him.
His book on violence was easy to read without being fun to read and this was similar, in that it was free of jargon but not hugely engaging. The central theme was the signficance of public knowledge, where information was made clear to everyone, and everyone was aware it was received by everyone. A lot of it dealt with hard logic and its impact on psychology, which unfortunately meant a lot of the logical steps had to be explained in detail, one of the ways in which my interest waned. Pinker posited that it affects many interactions, especially relating to status, and analysed the limits of our brains to interpret the iterations of "he believes that she believes that he believes x".
There were several times where everyday experiences were well-illustrated, such as single verbs like 'deceive' and 'bluff' making multi-layered relations easier to formulate in a single concept, or a scene from friends exploiting differences in knowledge. However there were also instances where Pinker was very ambitious in using this concept to explain crying, laughing and euphemism, and I thought crying and laughter required much more evidence to support his claims. These were quite theoretical, bordering on evolutionary psychology, and lacked rigour. Laughter is often employed as much to pick on the underdog as pierce the hierarchy, and this was acknowledged and dismissed almost instantly.
Euphemism was explained by plausible deniability in case of rebuff, especially in relation to dating. This didn't outline why it was used in other contexts however, such as death, which ambiguity is not desired. There was too little in terms of counterexamples as to why his theory was the only explanation rather than a possible explanation.
Overall this was a book that contained insights within it, rather than one that succinctly but elegantly covered the subject. Both the writing style and arguments contained within it could have been stronger, or in the case of university cancellation, much stronger - this seemed to be a vehicle to put his gripe on paper rather than adding to the scientific canon, even though I essentially agreed with him.
November 1, 2025
I’m uncertain about three aspects of this book, though I want to be cautious in my critique. My reservations may be more due to my lack of training in psychology, sociology, anthropology, or literary criticism than from any flaw in the book itself.
First, I’m not convinced that the central example—the emperor without clothes—functions in the way Pinker suggests. He presents it as an illustration of the shift from private to common knowledge, arguing that the boy’s outcry didn’t reveal anything new, but simply made what everyone already knew publicly acknowledged. However, my reading of The Emperor’s New Clothes differs. In the original tale, the con-men claim the clothes are invisible to the incompetent or stupid, creating a situation where each individual is unsure whether the emperor is clothed, or alternatively whether they themselves are simply unworthy of seeing the garments. The child’s cry, and the crowd’s reaction, do more than dramatise a shift to common knowledge—they resolve uncertainty. Each person learns that others also see nothing, and therefore the premise must be false. In that sense, the boy’s statement does convey new information to each listener. That seems significant.
Second, I’m unsure about the value of pursuing the recursive logic that underpins statements like “he knows that she knows that he knows…” ad infinitum. This idea recurs multiple times throughout the book, but beyond the first few iterations, I struggle to see its utility, even in concept. It’s clear that humans can’t process beyond a few iterations, but the question in my mind is not whether it’s possible, but whether it’s meaningful. Is there analytical value in reasoning five, twenty even 20,000 levels deep? I'm unconvinced.
Third, more broadly, I question whether the core concept of common knowledge warrants the book’s length—especially the first 260 pages, which contain a large number of examples and variations that may exceed what the central idea can sustain. For me, Chapter 8, The Canceling Instinct, stands out as the most interesting, perhaps because it feels more personal to the author. But its strength seems to derive less from its connection to the book’s main thesis than from its standalone insights.
I've read most of Pinker's other books, and while I enjoyed this one, I found the others to be more interesting and richer.
First, I’m not convinced that the central example—the emperor without clothes—functions in the way Pinker suggests. He presents it as an illustration of the shift from private to common knowledge, arguing that the boy’s outcry didn’t reveal anything new, but simply made what everyone already knew publicly acknowledged. However, my reading of The Emperor’s New Clothes differs. In the original tale, the con-men claim the clothes are invisible to the incompetent or stupid, creating a situation where each individual is unsure whether the emperor is clothed, or alternatively whether they themselves are simply unworthy of seeing the garments. The child’s cry, and the crowd’s reaction, do more than dramatise a shift to common knowledge—they resolve uncertainty. Each person learns that others also see nothing, and therefore the premise must be false. In that sense, the boy’s statement does convey new information to each listener. That seems significant.
Second, I’m unsure about the value of pursuing the recursive logic that underpins statements like “he knows that she knows that he knows…” ad infinitum. This idea recurs multiple times throughout the book, but beyond the first few iterations, I struggle to see its utility, even in concept. It’s clear that humans can’t process beyond a few iterations, but the question in my mind is not whether it’s possible, but whether it’s meaningful. Is there analytical value in reasoning five, twenty even 20,000 levels deep? I'm unconvinced.
Third, more broadly, I question whether the core concept of common knowledge warrants the book’s length—especially the first 260 pages, which contain a large number of examples and variations that may exceed what the central idea can sustain. For me, Chapter 8, The Canceling Instinct, stands out as the most interesting, perhaps because it feels more personal to the author. But its strength seems to derive less from its connection to the book’s main thesis than from its standalone insights.
I've read most of Pinker's other books, and while I enjoyed this one, I found the others to be more interesting and richer.
November 22, 2025
Steven Pinker’s “When Everyone Knows That Everyone Knows...: Common Knowledge and the Mysteries of Money, Power, and Everyday Life” is a wide‑ranging exploration of how shared awareness underpins coordination, conflict, and cooperation in modern life. It offers an accessible synthesis of game theory, cognitive psychology, and social observation aimed at general readers interested in why societies sometimes work smoothly—and sometimes break spectacularly. Pinker defines “common knowledge” not as something everyone privately knows, but as a state where each person knows it, knows that others know it, and so on in a recursive loop. This seemingly abstract notion becomes his master key for explaining mass phenomena such as market bubbles, bank runs, political uprisings, and viral online pile‑ons. A major strength of the book is its treatment of financial markets and collective action problems. Pinker shows how expectations about what others believe can levitate asset prices, then abruptly reverse when doubts become common knowledge, generating crashes, runs, and crises. He extends the same logic to revolutions and authoritarian politics, arguing that regimes are most vulnerable when awareness of their weakness suddenly becomes public and mutually acknowledged. Pinker is equally interested in mundane situations: first dates, office politics, etiquette, and the fine line between flirtation and harassment. He explains how innuendo, white lies, and “benign hypocrisy” help people manage situations where everyone suspects what is going on but prefers to avoid making it common knowledge. These chapters illustrate how conventions, rituals, and even emotional displays like blushing or laughter serve as “common knowledge generators.” Stylistically, the book combines thought experiments, literary references, and examples from pop culture, continuing Pinker’s trademark blend of analytic rigor and breezy illustration. Its great educational value lies in giving readers a single, powerful concept they can apply to news events, institutions, and personal relationships. Some may feel the core idea is reiterated too often or that complex political phenomena are overly reduced to coordination logic, but even skeptics are likely to come away seeing social life through a sharper, more strategic lens.
October 28, 2025
When Everyone Knows You Know
by Steven Pinker
Steven Pinker’s When Everyone Knows You Know is, at first glance, another of his polished excursions into the logic of human behavior. His premise—that much of social life depends on shared awareness and mutual knowledge—is sound and engaging. As always, Pinker writes with precision and a talent for making complexity seem almost conversational. Yet as the book unfolds, the tone feels more academic than revelatory, more an exercise in game theory than a journey toward deeper understanding.
Pinker’s argument builds on the idea that human interaction is shaped not only by what we know, but by what we know that others know. He illustrates this with a series of intricate examples—ingenious, but sometimes exhausting. They read like brainteasers, designed for the intellectually athletic. One can admire the elegance of the reasoning while still feeling that the point, somehow, remains just out of reach.
It may be that Pinker has written the kind of book that rewards future reflection more than immediate insight. There are passages that hint at a delayed resonance, ideas that might sharpen with time. But in the moment, the experience feels curiously thin. Pinker’s prose is as clear as ever, but the clarity seems to illuminate the surface of things rather than their depth.
One exception stands out: Chapter Nine, in which Pinker turns to the subject of cancel culture. His analysis here is direct, fair-minded, and quietly brave. He argues that the social cost of suppressing open dialogue is too high, and that a culture built on mutual fear cannot sustain rational thought. It’s the most human section of the book—less analytical, more concerned with intellectual integrity and the fragility of public discourse.
When Everyone Knows You Know will appeal to readers who enjoy the architecture of reasoning, who take pleasure in seeing thought constructed with mathematical precision. For others, it may feel like a work of admirable intelligence that never quite touches the ground. Pinker’s brilliance is evident on every page, but brilliance alone does not guarantee depth. The book offers light—bright, cold, and steady—but few shadows, and perhaps fewer surprises.
by Steven Pinker
Steven Pinker’s When Everyone Knows You Know is, at first glance, another of his polished excursions into the logic of human behavior. His premise—that much of social life depends on shared awareness and mutual knowledge—is sound and engaging. As always, Pinker writes with precision and a talent for making complexity seem almost conversational. Yet as the book unfolds, the tone feels more academic than revelatory, more an exercise in game theory than a journey toward deeper understanding.
Pinker’s argument builds on the idea that human interaction is shaped not only by what we know, but by what we know that others know. He illustrates this with a series of intricate examples—ingenious, but sometimes exhausting. They read like brainteasers, designed for the intellectually athletic. One can admire the elegance of the reasoning while still feeling that the point, somehow, remains just out of reach.
It may be that Pinker has written the kind of book that rewards future reflection more than immediate insight. There are passages that hint at a delayed resonance, ideas that might sharpen with time. But in the moment, the experience feels curiously thin. Pinker’s prose is as clear as ever, but the clarity seems to illuminate the surface of things rather than their depth.
One exception stands out: Chapter Nine, in which Pinker turns to the subject of cancel culture. His analysis here is direct, fair-minded, and quietly brave. He argues that the social cost of suppressing open dialogue is too high, and that a culture built on mutual fear cannot sustain rational thought. It’s the most human section of the book—less analytical, more concerned with intellectual integrity and the fragility of public discourse.
When Everyone Knows You Know will appeal to readers who enjoy the architecture of reasoning, who take pleasure in seeing thought constructed with mathematical precision. For others, it may feel like a work of admirable intelligence that never quite touches the ground. Pinker’s brilliance is evident on every page, but brilliance alone does not guarantee depth. The book offers light—bright, cold, and steady—but few shadows, and perhaps fewer surprises.
November 4, 2025
Pinker is a erudite and enjoyable writer. Every point he makes is enhanced by multiple vignettes and stories going back through much of history. There is simply a wealth of examples. On the other hand, his vocabulary is undoubtedly toned down from the technical jargon of cognitive psychology, but it is still noticeable.
Pinker is also a prolific author, so I think he does inevitably cover some of the same ground in this book as in previous efforts. His basic thesis is that shared, common knowledge is important in understanding human behavior, with the addition of games theory for how the unknowns in a situation are best (or typically) resolved. There is some similarity in his focus on common knowledge with Yuval Harari's books (such as Sapiens) with his focus on shared constructs being the basis for human behavior. Pinker does acknowledge this similarity.
I was struck by his observation: "This is the game-theoretic basis of the commonplace that many forms of entrenched inequality are arbitrary, and they they cannot be undermined by individuals renegotiating their relationships but only by a collective effort to overturn the norm." Not a focus of the book, but an intriguing observation.
I also noted his observation on humor: "They (theories of humor) single out as the essence of humor things that are not really funny: engaging in play, signaling safety, violating expectations, breaching norms, blending concepts, flaunting intelligence, asserting superiority, encouraging affiliation, encrypting messages, resolving inconsistencies, releasing tension. All of these experiences, to be sure, are sometime associated with humor, but most often they happen with a trace of mirth." This is a good example of Pinker's writing, with lists of remarkable detail in pursuit of a point.
In the end, I don't think anyone would actually argue that human behavior is determined by game theory, even if it provides a framework for the way to successfully navigate relational challenges.
Pinker is also a prolific author, so I think he does inevitably cover some of the same ground in this book as in previous efforts. His basic thesis is that shared, common knowledge is important in understanding human behavior, with the addition of games theory for how the unknowns in a situation are best (or typically) resolved. There is some similarity in his focus on common knowledge with Yuval Harari's books (such as Sapiens) with his focus on shared constructs being the basis for human behavior. Pinker does acknowledge this similarity.
I was struck by his observation: "This is the game-theoretic basis of the commonplace that many forms of entrenched inequality are arbitrary, and they they cannot be undermined by individuals renegotiating their relationships but only by a collective effort to overturn the norm." Not a focus of the book, but an intriguing observation.
I also noted his observation on humor: "They (theories of humor) single out as the essence of humor things that are not really funny: engaging in play, signaling safety, violating expectations, breaching norms, blending concepts, flaunting intelligence, asserting superiority, encouraging affiliation, encrypting messages, resolving inconsistencies, releasing tension. All of these experiences, to be sure, are sometime associated with humor, but most often they happen with a trace of mirth." This is a good example of Pinker's writing, with lists of remarkable detail in pursuit of a point.
In the end, I don't think anyone would actually argue that human behavior is determined by game theory, even if it provides a framework for the way to successfully navigate relational challenges.
October 27, 2025
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When Everyone Knows That Everyone Knows…: Common Knowledge and the Mysteries of Money, Power, and Everyday Life by Steven Pinker examines the concept of common knowledge. Mr. Pinker is a Canadian thinker, scientist, psychologist and author.
I’ve never read a book by Mr. Pinker, but I saw him on TV promoting this book and was impressed with the way he explains complex ideas. He also didn’t seem like a bullshitter, and has facts to backup everything he says.
When Everyone Knows That Everyone Knows… by Steven Pinker is one of those books that makes you think. I don’t pretend to understand everything in the book, but I understood most of it and the rest are topics I’m still thinking about.
Mr. Pinker agrees with, and gives credit to, Yuval Noah Harari that fictional stories can make millions of people work towards a common goal. These powerful narratives became even more powerful as technology made it easier and easier to communicate and spread the common goal.
I had to go back and read some sections, not that it wasn’t interesting but some examples needed to be read much more carefully and keep several thoughts in my head in order to follow them. It wasn’t always easy and I wasn’t always successful, but it was a great brain exercise if nothing else.
The most interesting aspect of this book is the exploration of social knowledge and its dynamics. This was the first book I read by the Mr. Pinker, so I can’t compare it to his other books but I’ll look forward to reading more.
When Everyone Knows That Everyone Knows…: Common Knowledge and the Mysteries of Money, Power, and Everyday Life by Steven Pinker examines the concept of common knowledge. Mr. Pinker is a Canadian thinker, scientist, psychologist and author.
I’ve never read a book by Mr. Pinker, but I saw him on TV promoting this book and was impressed with the way he explains complex ideas. He also didn’t seem like a bullshitter, and has facts to backup everything he says.
When Everyone Knows That Everyone Knows… by Steven Pinker is one of those books that makes you think. I don’t pretend to understand everything in the book, but I understood most of it and the rest are topics I’m still thinking about.
Mr. Pinker agrees with, and gives credit to, Yuval Noah Harari that fictional stories can make millions of people work towards a common goal. These powerful narratives became even more powerful as technology made it easier and easier to communicate and spread the common goal.
I had to go back and read some sections, not that it wasn’t interesting but some examples needed to be read much more carefully and keep several thoughts in my head in order to follow them. It wasn’t always easy and I wasn’t always successful, but it was a great brain exercise if nothing else.
The most interesting aspect of this book is the exploration of social knowledge and its dynamics. This was the first book I read by the Mr. Pinker, so I can’t compare it to his other books but I’ll look forward to reading more.
October 16, 2025
I have yet to come across a book written by Steven Pinker that failed to make me think, and this is no exception. This book is about "how we think about each other's thoughts about each other's thoughts, ad infinitum". That is, we not only try to be thought readers, but also think about how the other person is trying to read our thoughts, or how the other person is trying to decode our thought reading, and it goes back and forth. Sometimes we are aware that some fact is publicly known, and everyone knows that everyone knows this fact. These are termed as "common knowledge". In this book, Pinker explores this awareness and shows how deeply it affects everything we do, from social interactions to politics and economic activities.
Having read many of his books, I can say that this one contains many ideas that appeared in his earlier work. That is hardly a complaint, as there is essential continuity in everyone's thinking. But it is a very clever book that covers a wide range of scenarios. People familiar with Yuval Harari's popular book, Sapiens, will find some similar threads, but Pinker is more thorough in defining his thesis.
The book is also full of clever logical problems and anecdotes that should entertain any thoughtful and curious reader. Many of the behavioral experiments he describes are also delightful and thought-provoking. I would strongly recommend this book to anyone who finds our species endlessly fascinating.
Having read many of his books, I can say that this one contains many ideas that appeared in his earlier work. That is hardly a complaint, as there is essential continuity in everyone's thinking. But it is a very clever book that covers a wide range of scenarios. People familiar with Yuval Harari's popular book, Sapiens, will find some similar threads, but Pinker is more thorough in defining his thesis.
The book is also full of clever logical problems and anecdotes that should entertain any thoughtful and curious reader. Many of the behavioral experiments he describes are also delightful and thought-provoking. I would strongly recommend this book to anyone who finds our species endlessly fascinating.
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