Game theory is the study of strategic interaction — how rational agents make decisions when the outcome depends not just on what they do, but on what others do.
It sounds abstract but it’s everywhere. Every negotiation, every market, every political election, every social interaction involves game theory whether you know it or not.
The classic games:
Prisoner’s Dilemma — two suspects can cooperate (stay silent) or defect (rat each other out). Individual rationality leads to both defecting, even though both cooperating would be better. This explains why cooperation is hard and why trust is valuable.
Coordination Game — both players benefit from choosing the same option (driving on the same side of the road). The challenge is agreeing which option without communication. This is why standards, norms, and conventions exist.
Chicken — two drivers heading toward each other. First to swerve loses face; neither swerving means both crash. Explains nuclear brinksmanship, business standoffs, and many political negotiations.
Repeated games — when you play the same game many times with the same people, everything changes. Reputation matters. Tit-for-tat (cooperate first, then mirror what the other does) turns out to be remarkably effective. This is why long-term relationships produce more cooperation than one-off interactions.
Key concepts:
- Nash Equilibrium — a stable state where no player can improve their outcome by changing strategy alone. Not necessarily the best outcome — just a stable one.
- Zero-sum vs. positive-sum — in zero-sum games, one person’s gain is another’s loss. In positive-sum games, everyone can win. Most real-world situations are positive-sum, but people often mistakenly treat them as zero-sum.
- Signaling — actions that communicate information. A college degree signals competence (whether or not it actually develops it). Expensive advertising signals a company plans to stick around.
The deepest lesson of game theory: the structure of the game matters more than the players. Change the rules and you change the behavior. This is why institutional design — how you set up the game — is more important than finding good players.
Related: Economics, microeconomics, Persuasion