It’s the study of strategic decision-making where each player’s best choice depends on what the others do. It models interactions as "games" with players, options, and payoffs to predict and explain behaviour.

What is a simple example of game theory?

The prisoner’s dilemma: two people are each better off betraying the other, so both betray and both end up worse than if they’d cooperated — individual rationality producing a bad joint outcome.

Why is game theory useful?

It reveals why rational individuals sometimes reach poor collective results — price wars, arms races, overfishing — and helps design rules and incentives so self-interested players are steered toward better outcomes.

Game theory

Mathematics & strategy

Game theory is the study of strategic decisions, where your best move depends on what others choose and theirs depends on you. It models situations as "games" with players, choices, and payoffs — revealing why rational individuals sometimes reach bad collective outcomes.

How it works

Map the players, their possible choices, and the payoff each combination gives everyone. Then reason about how others will act in their own interest, and choose your move anticipating theirs — looking for equilibria where no one can improve by changing alone.

How to use it

Anticipating competitors’, negotiators’, or rivals’ responses to your moves.
Understanding why arms races, price wars, and overfishing happen despite hurting everyone.
Designing rules and incentives so that self-interested players reach good outcomes.

Worked example

Two rival shops both want to cut prices to win customers. If both hold, both profit; if one cuts, it grabs the market; fearing that, both cut — and both end up worse off. Individually rational choices produce a collectively bad result.

Where it fails

Classic game theory assumes rational, self-interested players with known payoffs — real people are emotional, cooperative, repeat the game, and misread the stakes. The models illuminate the logic but rarely capture the full mess of human behaviour.

The deeper point

Its most important lesson is uncomfortable: many disasters require no villains. When payoffs are structured a certain way, perfectly reasonable people produce ruin together — so the fix is usually the rules of the game, not the morality of the players.

Frequently asked

What is game theory?: It’s the study of strategic decision-making where each player’s best choice depends on what the others do. It models interactions as "games" with players, options, and payoffs to predict and explain behaviour.
What is a simple example of game theory?: The prisoner’s dilemma: two people are each better off betraying the other, so both betray and both end up worse than if they’d cooperated — individual rationality producing a bad joint outcome.
Why is game theory useful?: It reveals why rational individuals sometimes reach poor collective results — price wars, arms races, overfishing — and helps design rules and incentives so self-interested players are steered toward better outcomes.

Second-order thinking Tragedy of the commons Incentives

Editorial synthesis © ReadGlobe 2026, drawing on the mental-models tradition (Charlie Munger, Farnam Street) and the primary sources for each model. · Last reviewed 2026-05-29.