Everywhere at Once

The same trap shows up far beyond a police station:

• Arms races: two rivals each build weapons nobody wants to use, just so the other side does not get ahead.
• Climate change: every country gains from burning fuel, while quietly hoping everyone else cuts back.
• Price wars: two stores keep undercutting each other until both margins collapse.

In each case, what is best for one player drags the whole group toward the worse outcome.

Enter the Tournament

Play the dilemma just once and betrayal wins. But what if the same two players meet over and over? Around 1980, political scientist Robert Axelrod tested this by inviting experts to submit strategies and pitting them against each other for hundreds of rounds.

The champion was almost embarrassingly simple: Tit-for-Tat. Start by cooperating, then do whatever your opponent did last move. It beat every clever, complicated rival in the field.