The hardest moments in working with others often come when you feel the other person might betray you. If both sides trust each other, both can benefit. But if only one side keeps the promise, that side loses. That is why we often ask, “Am I the only one being foolish?”
The extended EBS program Hobby Is Science explains this familiar anxiety through game theory. Professor Choi Jung-kyu uses the language of economics and evolutionary science to show why human societies have created cooperation even in situations where betrayal appears profitable. The key is not goodwill alone. Repetition, reputation, the possibility of retaliation, institutions, and rules for handling free riders must work together.

Game Theory Is a Tool for Choices Involving Other People
Game theory is not a problem you calculate alone. Your own choice matters, but you also have to anticipate what the other person will choose. That is why game theory is used in economics, politics, biology, and psychology. It can explain not only human choices but also animal survival strategies and conflicts between states.
The video begins with a scene in which participants choose between split and take all for a reward of one million won. If both choose split, they share peacefully. If only one chooses take all, that person takes everything. If both choose take all, nobody gets anything. It is very simple, but it reveals the tension between trust and betrayal.

The Prisoner’s Dilemma: Each Person Is Rational, Yet the Result Gets Worse
The prisoner’s dilemma is uncomfortable not because humans are irrational. It is uncomfortable because the more each person calculates their own interest, the closer the group can move toward a bad result. If you cannot be sure the other side will cooperate, betrayal can look like a fairly safe choice.
But if everyone thinks that way, cooperation disappears. A choice that is rational for the individual becomes harmful for the group as a whole. Competition between departments, price wars, public resource use, and information sharing inside organizations often resemble this structure.

The Tragedy of the Commons: Everyone Can Work Hard and Still Fail Together
The tragedy of the commons is even more everyday. If each person releases more cattle onto a shared pasture, the individual gains. But if everyone acts the same way, the pasture is destroyed. Nobody may have malicious intent, yet the result becomes the worst possible outcome.
This concept does not explain only environmental problems. Similar situations occur inside organizations. Someone who uses too much meeting time, someone who does not maintain shared documents, or someone who only consumes the team’s trust is also wearing down a kind of commons. Cooperation cannot be maintained by goodwill alone. Rules are needed for managing shared resources.

Tit-for-Tat: Cooperation Is Not Naivety, but Generosity with Memory
The core idea in the latter part of the video is the tit-for-tat strategy. Tit-for-tat begins by cooperating, and after that it responds according to the other side’s previous action. If the other side cooperates, I cooperate. If the other side defects, I respond with defection next time. But if the other side returns to cooperation, I also return to cooperation.
This strategy is interesting because it is simple. It shows goodwill first. It does not ignore betrayal. But it also does not seek revenge forever. A cooperative society needs this balance. If you are only nice, you are exploited; if you only suspect others, no relationship lasts long.

Five Conditions That Create a Cooperative Society
- A structure where people meet repeatedly is needed, rather than one-off encounters.
- Reputations should remain for those who keep promises and those who break them.
- Betrayal should carry a cost, but there should also be a chance to recover.
- Rules for using shared resources must be clear.
- Institutions must not leave free riders unattended.
Cooperation does not appear automatically just because many kind people gather. We must create a structure in which good people can endure. Game theory may look like cold calculation, but in practice it helps us design better communities.

The Message This Video Gives to Work and Organizations
When cooperation collapses in an organization, people blame personalities: “That person is selfish” or “Our team has no culture of collaboration.” Of course, individual attitudes matter. But game theory asks one step further: is the current structure rewarding betrayal?
If performance is evaluated only at the individual level, information sharing decreases. If the cost of failure is too high, nobody tries first. If responsibility is vague but rewards are competitive, people move defensively. If you want cooperation, you need to change the rules of the game more than the slogans.
Related Reading
- The Psychology of People Who Hurt Only Their Family: How Not to Lose Courtesy with Those Closest to You
- Your Team Member May Not Be Slow: The Difference Between Method and Speed That Leaders Miss
- The Decisive Difference Between Companies That Collapse and Companies That Grow Again in the AI Era
- Human Value in the AI Era: What Should Irreplaceable People Prepare?
FAQ
What is game theory?
Game theory is a tool for analyzing situations where another person’s choice affects your outcome. It began in economics but is widely used in politics, biology, psychology, and organizational management.
Why is the prisoner’s dilemma important?
It shows that choices rational for each individual can create bad outcomes for the whole. It helps us see cooperation failure as a structural problem, not only a personality problem.
Does the tragedy of the commons apply only to environmental issues?
No. It applies to any situation involving shared resources. Organizational time, trust, information, and shared documents can also collapse like a commons if they are not managed.
What does tit-for-tat mean?
It is a strategy that cooperates first and then responds according to what the other side did immediately before. It answers cooperation with cooperation and betrayal with betrayal, but returns to cooperation when the other side comes back.
What is needed to build a cooperative organization?
Repeated relationships, reputation, clear rules, costs for betrayal, and opportunities for recovery are needed together. Rather than simply demanding good intentions, it is important to create a structure where cooperation is not a loss.