110 likes | 267 Views
Cooperation. PLSC 379R Lecture 4. Waltz vs. Sagan in South Asia. We know Waltz is a realist, can you tell that from the argument he makes? What would you say Sagan is?. Time Keeps on Slippin’, Slippin’, Slippin’. Shadow of the future Iterated PD
E N D
Cooperation PLSC 379R Lecture 4
Waltz vs. Sagan in South Asia • We know Waltz is a realist, can you tell that from the argument he makes? • What would you say Sagan is?
Time Keeps on Slippin’,Slippin’, Slippin’ • Shadow of the future • Iterated PD • Potential benefits of future interactions (and/or the probability of future interactions) must be higher than the temptation to defect in the immediate round
Axlerod’s Showdown • Axlerod hosted a tournament where different computer programs played different strategies • All D • Permanent Retaliation (Grim Trigger) • TIT for TAT • Downing
Lessons • Be nice! • Be forgiving! • In the second tournament, some strategies tried to take advantage of the nice and forgiving. They were able to do so in some situations, but did not do well in the tournament.
Should We Care? • Why did TFT work in the tournament? • Would it work in the “real world”? • How are people the same/different from the computer programs? • Did we learn anything useful?
Invasion • Let’s say the world is an archetype realist model • Can cooperation emerge? • Can TFT invade a world of meanies? • You Betcha!!!
Invasion • Must be provoked on first defection • 30p + 9(1-p) > 10? • T=5, R=3, P=1, S=0 • 7 meanies and 3 TFT = meanie 102, TFT 123 • 8 meanies and 2 TFT = meanie 98, TFT 102 • 9 meanies and 1 TFT = meanie 94, TFT 81 • So TFT needs to invade in a group
Invasion • Can ALL D invade a world of TFT? • Not if w is sufficiently large • The mathematical proof is in appendix B
Commitment Problems • Actors can lie about the strategy they intend to play, so commitment is a problem • Iteration helps some • Actions speak louder than words • An actor playing TFT must be willing to get suckered on the first move • How to break out of a cycle of both D?
Read for Paper • Everyone should look at chapter 7 (How to Promote Cooperation) for their paper