Common Knowledge: The Divine Tool for Mass Obedience

Have you ever had this experience: facing a celebrity whose work you don’t genuinely like, perhaps even finding it mediocre? Yet, upon hearing they’re performing locally, you unconsciously check ticket prices, or even join the scramble for tickets; if they occasionally endorse a product, you might casually place an order; and if they actually stood before you, your heart would skip a beat, filled with an inexplicable awe.

What exactly is it that you revere?

It’s not the person themselves, but the attention they gather—the fact that “everyone acknowledges they are important.”

The mechanism behind this phenomenon is far grander than mere celebrity effect. The cognitive tool we’re discussing today is precisely the “divine tool” of rulers, named “common knowledge.”

Making one person obey can be based on fear, trust, respect, or love; making a group of people obey requires leadership, narrative ability, or control of armed forces. However, to make “an entire populace”—not just a group, but everyone within your jurisdiction—willingly obey, it doesn’t rely on your personal qualities and abilities.

It relies on another force: they saw each other obeying.

Common knowledge is like a hall of mirrors reflecting each other. Whoever masters it holds the master switch to synchronize the actions of an entire populace.

What is Common Knowledge? Starting from the Depths of “Knowing” #

The concept of “common knowledge” was first proposed by American philosopher David K. Lewis in 1969 [1], who first recognized that human societal coordination relies on common knowledge. Israeli-American economist Robert J. Aumann, in 1976, provided a more rigorous formal expression for it based on game theory [2].

While this theory sounds novel, its core principle is quite simple. Generally speaking, there are three depths of “knowing” about an event:

The first is “private knowledge”: I know, but I don’t know if you know.

The second is “mutual knowledge”: I know, you know, and perhaps everyone knows. However, no one has explicitly stated it, and no one dares to guarantee that the other person definitely knows.

The third is called “common knowledge”: I know, you know, and I know you know, and you know I know, and I know you know I know, and you know I know you know I know… nested endlessly, to infinity.

So, you might ask, why the need for such “fuss” about common knowledge? Isn’t “you know, I know” enough? The answer is: no, it’s not. Let me give you an analogy: we each lead an army, preparing to sandwich the enemy from north and south, and success is only possible if both of us strike simultaneously.

Tonight, I send a messenger to you with a letter, agreeing that you will dispatch troops tomorrow morning. Upon receiving the letter, will you immediately decide to send troops? No. You must confirm that I know you received the letter—so that I will definitely send troops tomorrow morning—only when this condition is met will you dare to dispatch your army.

So you send a messenger back to me, saying: “I received it, let’s both send troops tomorrow morning.”

However, this return letter might also be intercepted by the enemy. So after I receive your reply, I will think: Do you know that I have received your reply? If you don’t know, will you worry that I haven’t received it and therefore not dare to send troops?

So I would have to send another messenger to tell you: “I know you know.”

But this messenger might also be intercepted. So you would worry again: Do I know that you know that I know?

You see, each additional letter only advances certainty by one layer, yet always leaves the next layer uncertain.

To ensure coordinated action, information must become common knowledge for both of us, just like a direct face-to-face conversation. Perhaps we could both light beacon fires on a mountaintop simultaneously; I see it in the south, you see it in the north, and we both clearly know that the other has also seen it, resolving this nesting naturally.

…Of course, if we do that, the enemy will also see it. Therefore, transforming mutual knowledge into common knowledge often faces difficulties. Many times, I truly cannot be sure whether you know.

The most classic example of common knowledge is The Emperor’s New Clothes.

Everyone privately thought the emperor was naked, but what if their own judgment was flawed, and they were mistaken? Perhaps others could see the clothes? Until a child cried out. Once one person shouted, another followed. When more people around you started shouting, you dared to join in.

The child upgraded private knowledge to mutual knowledge, and those who followed upgraded mutual knowledge to common knowledge. All of this happened almost instantaneously, and the coordination of the crowd changed immediately thereafter.

Private knowledge might allow you to see the truth, but common knowledge is what empowers you to act.

Focal Points, Rituals, and the Allure of Celebrities: The Application of Common Knowledge #

Aumann and Thomas Schelling jointly received the 2005 Nobel Memorial Prize in Economic Sciences for their analysis using game theory, which enhanced our understanding of conflict and cooperation. Their research is closely related to common knowledge.

In fact, the “focal point” mentioned by Schelling earlier is itself a form of common knowledge. For instance, Grand Central Station is a landmark familiar to all New Yorkers; therefore, when people arrange a meeting place, both you and I can coincidentally guess that location, allowing it to become a focal point and play a role in coordinating the game.

“Ritual” is also a form of common knowledge. It’s not that the process itself is inherently correct; we comply with it because it is sufficiently conspicuous.

Conspicuous means correct; to be seen is to begin to be obeyed.

This is also why celebrities inspire awe.

American historian Daniel J. Boorstin famously said: a celebrity is “well-known for his well-knownness” [3].

You revere him not because of his personal greatness, but because he is “popular.”

Rituals: The Secret Weapon for Manufacturing Common Knowledge #

So, how exactly are celebrities “forged”? Is it by releasing a good work today, and another tomorrow, and over time naturally becoming a celebrity? No. Common knowledge is not accumulated progressively; it requires a kind of sudden, transformative creation.

Celebrities are crowned through a series of rituals.

The red carpet is to let everyone see him being seen; trending topics are to let everyone know he is being discussed; fan greetings at the airport transform private admiration into a public queue; endorsement posters make his face occupy the city’s daily sight; award ceremonies are where peers and media crown him; concerts allow a group of people to simultaneously confirm, “so many people like him just like me.”

These rituals are not designed to prove how excellent he is, but to prove that he is at the center of common attention.

Korean-American political scientist Michael Suk-Young Chwe published a short book in 2001, Rational Ritual, which was later even specifically recommended by Zuckerberg [4].

Chwe posed a somewhat “strange” question: why are humans so keen on holding circular, centripetal gathering rituals?

Whether it’s the Roman Colosseum, the Kaaba in Mecca, or formations standing centripetally in a square, their forms vary, but the mechanism is the same: an inward-facing circle, allowing everyone to see everyone.

You not only see the ritual happening at the center, but you also see that everyone else is watching this ritual, and you see that they also see you watching.

The power of a ritual lies not in its ability to transmit meaning from the center to you alone, but in its ability to assure you that others have also received the same meaning. The core function of a ritual is to transform a particular meaning into common knowledge.

Chwe also offers a more modern example: why are Super Bowl commercials so expensive? [5]

That is the most expensive advertising slot in the United States, its status comparable to China’s Spring Festival Gala. Today, a regular 30-second Super Bowl ad costs millions of dollars, with prime slots commanding astonishing prices, and this doesn’t even include the enormous costs of production, celebrity endorsements, and pre- and post-marketing. Yet, if you look at the products being advertised, most are household names: beer, potato chips, soft drinks, cars, insurance, food delivery, mobile phones, movie trailers, streaming platforms… Since these products already have sufficient brand recognition, what is the point of spending such a huge sum?

The significance lies in this sense of ritual. What these advertisements truly aim to do is not to transmit information, but to create common knowledge: to let you know that everyone knows this brand is still present, financially powerful, and belongs to the common life of Americans. This is like ancient nobles attending court ceremonies: you are not there to introduce your name to the emperor, but to let everyone see: I am still in this circle.

By the same token—

The Weibo trending list is not news, but a ritual. It doesn’t tell you “what happened,” but “what everyone is watching.”

Blue V verification, follower counts, sales rankings, “100,000 items sold,” the Double Eleven real-time transaction volume big screen, concerts selling out in seconds, premiere red carpets—all these are the same kind of mechanism: they don’t patiently persuade you that “this thing is good,” but rather broadcast to you: “Look, everyone approves of it.”

Rituals target not your judgment, but your coordination instinct.

Now, think about the large conferences you attended from childhood. The leaders spoke in boilerplate phrases, the procedures were meticulously rehearsed, who sat where, who spoke, who received awards—the entire content was devoid of suspense. The public generally knows that “important matters are discussed in small meetings, minor matters in large meetings, and the most important matters are not discussed at all.” So, why are these large conferences still held?

Because the focus of such conferences is inherently not information, but the creation—or more often, the reaffirmation—of common knowledge: the organization still has a center, the center can still convene a crowd, and everyone is still willing to sit here according to the same order.

You are not listening to the leader speak; you are watching your colleagues listen to the leader speak; and your colleagues are also watching you listen to the leader speak.

Scaled Governance: The Political Power of Common Knowledge #

As mentioned earlier, there are two paths to gaining status: domination and prestige. While both methods can compel obedience, their scope of influence is quite limited.

However, scaled governance must rely on common knowledge. The vast majority of people may not know you at all, understand you, or even believe you are particularly capable, yet they still choose to obey—this is precisely the effect that common knowledge can achieve.

Firstly, since others have already obeyed, I had better choose to obey as well. But more importantly, even if I want to resist, as long as I don’t see others resisting, I should not resist, because my unilateral resistance is bound to be ineffective.

Zhao Gao’s “pointing to a deer and calling it a horse” utilized this very principle. That was not merely a loyalty test, but a ritual for manufacturing obedience.

Zhao Gao wanted you to publicly, in front of everyone, call a deer a horse. In this way, every minister could personally witness that every other minister also dared not stand up in opposition.

This instantly transformed the private thought of “none of us dare to defy Zhao Gao” into a block of common knowledge that no one could shake.

Furthermore, have you noticed that the emperors of the Ming and Qing dynasties held very stable positions? Even if an emperor was young and ignorant upon ascending the throne, or even made a series of mistakes later like the Chongzhen Emperor, among the multitude of capable officials in the court, no one dared to easily replace the emperor. You might ask, why is this? After all, during the Han and Tang dynasties in China, changing emperors was a common occurrence.

The answer is also common knowledge. The emperor’s authority did not stem from the emperor’s personal competence, nor from the officials’ loyalty, but from the common acknowledgment by everyone that “the imperial throne was the sole legitimate focal point.”

During the Han and Tang dynasties, there were several powerful focal points in the court—imperial relatives, powerful clans, influential ministers, military, and even eunuchs all had their stable spheres of influence. People understood that if several powers within the palace reached a tacit understanding, replacing an emperor was not unimaginable. This might not necessarily be interpreted as “rebellion”; it could easily be packaged as “purging corrupt officials near the emperor” or “acting under the Empress Dowager’s decree.”

After the Song dynasty, it was completely different. The aristocratic families had already perished during the Huang Chao Rebellion and the Five Dynasties and Ten Kingdoms period, civil officials were mostly commoners who rose through the imperial examinations, politically the power of military figures was weakened, and ideologically the lord-vassal relationship was further reinforced through Neo-Confucianism… The emperor gradually escalated from a political participant to the sole center of the entire order.

Court officials would, of course, still feud with each other, eunuchs would, of course, still wield power, and imperial relatives might still have influence—but these individuals were highly replaceable. Their struggle was over “who is closer to the emperor” and “who speaks for the emperor,” rather than “can the emperor be replaced?”

Imperial authority was the greatest common knowledge that sustained these forces. Even if you felt the emperor was incompetent, as long as you didn’t know that “others also publicly admitted the emperor could be replaced,” you wouldn’t dare take that step. The stability of the imperial throne was not because everyone genuinely supported it, but because everyone knew that everyone had to appear to support it.

Why Do Bad Situations Last So Long? #

Understanding how common knowledge operates allows us to comprehend why many situations that are clearly terrible and widely resented by almost everyone can still persist for extended periods.

Because the failure of complex large systems is extremely difficult to become common knowledge.

A soccer game has a final whistle and a scoreboard; victory or defeat is clear at a glance. The head coach must be replaced when necessary, and team tactics must be adjusted when necessary. However, if you are governing a complex, massive system, then almost no one can declare that you have “lost.”

Take the Russia-Ukraine War as an example. Putin has prolonged the war to this day, incurring huge casualties yet failing to achieve substantial territorial gains, and the national economy is also deteriorating daily, yet Putin’s position remains stable.

He has absolutely no need to concede defeat. He can simply declare that not only have we not lost, but our international standing has improved. Even if the economy struggles in some areas, there is always one sector that is better than before—for instance, industries related to military production are experiencing rapid growth. As long as there is no clear scoreboard, you can even package a battle loss as a victory. Even if a battle genuinely didn’t go well, you can attribute it to the enemy being too cunning or some countries engaging in conspiracies.

A startup company incurs losses for four consecutive years, its product fails to gain traction, and user growth stagnates… but as long as the CEO doesn’t admit failure, there’s always another explanation: the first year is called the “strategic investment phase,” the second year the “market education phase,” the third year the “organizational capability development phase,” and the fourth year “capital winter temporarily suppressed innovation.”

As long as there is no public, commonly acknowledged moment of reckoning, failure can be renamed, postponed, or packaged as a reason for the next round of funding.

This is the advantage of having the “divine tool” in hand. As long as you don’t issue an “edict of self-reproach,” no one can declare that you have lost. You still control common knowledge, and the Mandate of Heaven still rests with you.

Seeing Through and Creating: How to Master Common Knowledge #

So, what can be gained from understanding these principles? Their impact will be beyond imagination.

Firstly, we can gain more freedom. Next time you feel compelled to follow, purchase, or obey something out of impulse, you should distinguish between the thoughts “I genuinely like this” and “everyone says it’s good.”

You will find that many so-called passions are merely bowing to a focal point.

Seeing through it doesn’t necessarily mean you should expose it. This doesn’t imply that you should henceforth be at odds with the world. Conforming to common knowledge is a rational choice, and coordinated action itself is often a wise move. We are not against conforming; rather, we advocate for consciously conforming.

There will always be a moment when you order the dish that truly appeals to you most, instead of the one everyone else is ordering.

Furthermore, you can actively create common knowledge. If you want to mobilize a group of people, lead a team, drive a change, or accomplish something that requires collective effort, merely disseminating information is not enough; you must create common knowledge.

Do not send 100 emails; instead, gather these 100 people into one room, hold a full staff meeting, and ensure everyone’s approval is witnessed by all present. You can negotiate one-on-one privately beforehand, but at the large meeting, everyone must applaud for you.

Whoever can distill chaotic discussions into a statement everyone understands is creating common knowledge. Whoever can make dispersed individuals aware of each other’s presence is creating common knowledge. Whoever can transform private hesitation into public commitment is creating common knowledge.

The Establishment and Collapse of Common Knowledge #

Once common knowledge is established, it is extremely difficult to collapse. Empress Dowager Cixi was driven out of Beijing by the Eight-Nation Alliance, yet the Qing Dynasty did not immediately collapse; even if a well-known brand suffers successive scandals, and consumers verbally abuse it, its shelf presence won’t immediately disappear; even if a celebrity appears in a few bad films, as long as the red carpet, trending topics, endorsements, and fan base continue to operate, he hasn’t truly “capsized”…

However, a tipping point will always arrive: when scandals are no longer just scandals, but become “everyone knows that everyone no longer believes it”; when bad films are no longer just bad films, but become “everyone knows that everyone is no longer buying into it”; when a boss’s mistakes are no longer just private complaints, but become “everyone knows that everyone sees he’s no longer capable”—at this point, common knowledge will be broken through.

It is not broken through by facts, but by “facts becoming common knowledge.”

注释

[1] David K. Lewis, Convention: A Philosophical Study (Cambridge, MA: Harvard University Press, 1969).

[2] Robert J. Aumann, “Agreeing to Disagree,” The Annals of Statistics 4, no. 6 (1976): 1236–1239.

[3] Daniel J. Boorstin, The Image: A Guide to Pseudo-Events in America (New York: Atheneum, 1962).

[4] Michael Suk-Young Chwe, Rational Ritual: Culture, Coordination, and Common Knowledge (Princeton, NJ: Princeton University Press, 2001). Chinese edition: Rational Ritual: Culture, Coordination, and Common Knowledge, Renmin University of China Press, published September 2021.

[5] Michael Suk-Young Chwe, “Culture, Circles, and Commercials: Publicity, Common Knowledge, and Social Coordination,” Rationality and Society 10, no. 1 (1998): 47–75