The Core Lesson

In a one-shot encounter, betrayal is the rational move: you have nothing to lose and a free win to gain. The other person is a stranger you will never see again.

But in repeated encounters, the math flips. Today's betrayal invites tomorrow's revenge, and your reputation travels with you. Cooperation starts to pay. This is why trust grows naturally among people who expect to deal with each other again and again.

The Shadow of the Future

The dilemma exposes a sharp split between short-term and long-term thinking. A move that looks smart in a single round can be ruinous as a way of life.

What changes everything is the shadow of the future: the expectation that this person will be back. When you know the relationship continues, burning a partner today costs you all the cooperation you could have had tomorrow. Cooperation needs a future to protect.