Cobra Effect · Decisions and strategy
Tit for tat
Cooperate first, answer a betrayal once, then forgive.
7 cards, read aloud in 2:38, with a test and sources.
In 1980 a political scientist asked the world to send him programs.
Robert Axelrod wanted to know what a good strategy looks like when you have to deal with the same person again and again. Economists, mathematicians and psychologists sent 14 entries. He put them in a round robin and ran the game 200 times per pairing.
The game rewards betrayal and then punishes both of you for it.
Each round, both players either cooperate or betray. Whatever the other one does, betraying pays you more that round. But if you both betray, you both end up worse off than if you had both cooperated. Economists call it the prisoner’s dilemma.
The winner was 4 lines long.
Anatol Rapoport sent the shortest program in the tournament. Cooperate on the first move. After that, do whatever the other player did last time. That is the whole of it.
It never beat a single opponent, and it won anyway.
Against anyone at all, it either matches them or loses by one betrayal. It cannot beat you. It can only fail to lose by much. What it does is make the pair rich, and the tournament was scored on total points, not on head to head wins. Axelrod ran it again with 62 entries. It won again.
Axelrod pulled out 4 properties the winners shared.
Be nice. Never betray first. Retaliate. Answer a betrayal at once, so that nobody profits from testing you. Forgive. Go back to cooperating the moment they do. Be clear. A strategy nobody can read is a strategy nobody can cooperate with.
It has one bad habit, and it shows up when the world is noisy.
If a message goes astray and you answer something the other side never did, they answer that. Two copies of the strategy can lock into an echo of revenge that neither of them chose. The repair is to forgive slightly more than you were wronged.
How to carry it into a week that has people in it.
Start generous with everyone. Answer a real breach once, straight away, in proportion. Then drop it completely and go back to normal. And make sure people can tell which of those three you are doing.
Sources
- Effective Choice in the Prisoner’s Dilemma, Robert Axelrod, 1980. The report of the first tournament, its 14 entries, and why the shortest program won. Search the title for the paper in the Journal of Conflict Resolution.
- The Evolution of Cooperation, Robert Axelrod, 1984. The tournaments written up for everyone, with the four properties, and a chapter on soldiers in the trenches of 1914 who worked the same thing out under fire.
- Tit for tat, Wikipedia. The strategy, both tournaments, the trouble it gets into when signals are noisy, and the more forgiving variants that were invented to handle that.
Nearby ideas
- The prisoner’s dilemma. Why two sensible people can both choose the worst outcome.
- Schelling points. Without talking, people meet at whatever stands out.
- The tragedy of the commons. Why shared things get used up, and how communities stop it.
- BATNA. Your power in a negotiation is what you will do if you walk away.
- Explore and exploit. When to try something new, and when to stick with what works.
- First principles. Rebuild a problem from what must be true, not from what everyone does.
- Opportunity cost. The real price of anything is the best thing you gave up for it.
- Chesterton’s fence. Before removing a rule, find out why it was put there.