The Clumsy Game-Player You and a partner are playing an Iterated Prisoner's Dilemma. Both of you have publicly pre-committed to the tit-for-tat strategy. By iteration 5, you're going happily along, raking up the bonuses of cooperation, when your partner unexpectedly presses the "defect" button. "Uh, sorry," says your partner. "My finger slipped." "I still have to punish you just in case," you say. "I'm going to defect next turn, and we'll see how you like it." "Well," said your partner, "knowing that, I guess I'll defect next turn too, and we'll both lose out. But hey, it was just a slipped finger. By not trusting me, you're costing us both the benefits of one turn of cooperation." "True", you respond "but if I don't do it, you'll feel free to defect whenever you feel like it, using the 'finger slipped' excuse." "How about this?" proposes your partner. "I promise to take extra care that my finger won't slip again. You promise that if my finger does slip again, you will punish me terribly, defecting for a bunch of turns. That way, we trust each other again, and we can still get the benefits of cooperation next turn." You don't believe that your partner's finger really slipped, not for an instant. But the plan still seems like a good one. You accept the deal, and you continue cooperating until the experimenter ends the game. After the game, you wonder what went wrong, and whether you could have played better. You decide that there was no better way to deal with your partner's "finger-slip" - after all, the plan you enacted gave you maximum possible utility under the circumstances. But you wish that you'd pre-committed, at the beginning, to saying "and I will punish finger slips equally to deliberate defections, so make sure you're careful." The Lazy Student You are a perfectly utilitarian school teacher, who attaches exactly the same weight to others' welfare as to your own. You have to have the reports of all fifty students in your class ready by the tim