06/02/2026
The Prisoner’s Dilemma
The Prisoner’s Dilemma is a game theory model in which two players acting in their own self-interest choose to defect rather than cooperate, even though mutual cooperation would lead to a better outcome for both.
The picture shows a classic example from game theory called the Prisoner’s Dilemma, where two individuals, A and B, must each decide whether to cooperate by staying silent or defect by betraying the other. The important twist is that neither prisoner knows what the other will choose, and their outcomes depend on the combination of both decisions.
If both prisoners stay silent, they are cooperating with each other. Because neither confesses, the police lack evidence, so each serves only 1 year. This is the best joint outcome for the two of them together.
If A stays silent while B betrays him, A is punished heavily with 3 years in prison, while B goes free. The reverse happens if A betrays while B stays silent. In either case, the betrayer gets the best personal outcome, and the silent prisoner suffers the worst.
But if both A and B betray each other, neither gains an advantage, and they both end up serving 2 years. This outcome is worse for both than mutual cooperation, yet better than being the only prisoner who stayed silent.
The dilemma is that although cooperation gives the best joint outcome, the incentive to betray is strong because defecting always gives a better personal result regardless of what the other person does. As a result, both prisoners usually choose to defect, and they end up with 2 years each, which is worse than the 1 year they would have served if they had both cooperated.