Walking the Dilemma

Walking a prisoner's dilemma means laying out all four outcomes, checking each party's best move against both of the other's choices, and locating the trap.

Two suspects, separated. If both stay silent, each serves one year. If both confess, each serves five. If one confesses while the other stays silent, the confessor walks and the silent one serves ten. Now reason as suspect one. If suspect two confesses, confessing gets five years instead of ten — confess. If suspect two stays silent, confessing gets zero instead of one — confess again. Confessing wins either way, and suspect two runs the same reasoning. So both confess and serve five, when mutual silence cost one. Each played flawlessly; together they bought the worse world. That is the trap: individual rationality, summed, defeating everyone — and why an enforceable agreement, which changes the payoffs, rescues both.