“I will begin on the assumption of mutual cooperation. If you cheat on me, however, not only will I refuse to cooperate, but I will punish you, even to my own near-term detriment. After some time, though, I might forgive you and try cooperating again, just in case your cheating was an error or a miscommunication, or on the chance you have reformed your ways. If, however, you cheat again, the probability of my forgiving you again will become lower and my punishment even more terrible.”
