Why Nice Guys Win

The result that stunned game theorists was this: the nicest strategies tended to win. Three of the strongest were all forgiving in their own way:

• Tit-for-Tat: never betrays first; mirrors the last move.
• Generous Tit-for-Tat: sometimes forgives even an unprovoked betrayal.
• Pavlov: repeats a move that paid off, switches after one that did not.

The aggressive strategies grabbed early points by exploiting others, then drew retaliation from every side and sank. When losing strategies are dropped over repeated rounds, cooperators come to dominate.