── ── Mental model

Prisoner's Dilemma

Whatever the other party does, each player is individually better off defecting — so both defect, and both end up worse than mutual cooperation. This is the structural skeleton beneath price wars, arms races, overfishing, and ad spend spirals. The problem is never character; it is structure. Exhortations to cooperate fail. Change the matrix.

How it works

Run the Game Diagnosis. Diagnose first, then redesign.

1. State the players and choices. Who are the parties? What are the two actions each can take? If you cannot reduce the situation to a small number of players and moves, the PD lens probably doesn't fit. 2. Write the payoff matrix. Fill in all four cells: (C,C), (C,D), (D,C), (D,D). Use real numbers or ordinal rankings (1st-best through 4th-worst). The diagnosis requires numbers — you cannot identify the structure by intuition alone. 3. Check whether it is a Prisoner's Dilemma. The defining ordering: T > R > P > S (and typically 2R > T + S). If T > R > S > P it is Chicken. If R > T there is no dilemma. 4. Identify the dominant strategy. In a true PD, "defect" dominates regardless of what the other player does (T > R; P > S). This is why the trap is structural. 5. Identify the equilibrium. Both defect → both get P, even though both prefer R. Nash equilibrium = the trap. 6. Design the escape. Four mechanisms: Repetition (shadow of the future); Reputation (third-party observation); Enforcement (contract/law changes payoffs); Matrix transformation (vertical integration, side payments, pre-commitment devices). 7. Pick the right escape and test it. Each mechanism has costs and prerequisites — diagnose which is actually available. Re-draw the post-escape matrix: if defection is still dominant, the escape is theatrical.

When to use it

• user asks 'why does everyone keep doing X when it's obviously bad for all of us', 'how do we get out of this race to the bottom', 'should we trust them not to defect', 'we'd both be better off cooperating but it never happens', 'is this a prisoner's dilemma / Nash equilibrium / tragedy of the commons / race to the bottom'

Worked example

Flood, Dresher, and Tucker — RAND, 1950

The Prisoner's Dilemma was not derived from a story. The story was attached to the matrix after the matrix had already been written down and observed to misbehave in a laboratory.