If the players co-operate by being nice to each other, then both truce; but then one player can win by being mean. So is co-operation rational or not? Given repeated plays in a tournament, negotiation and reciprocation are possible. Mutual profit gives incentive to mutual aid; but exploitation remains tempting. There are many different strategies for dilemma play. I call three of them the “Iron”, “Gold”, and “Silver” rules.
The Iron rule is the rule of rigid exploitation, justified in the name of expediency. Players ruled by the Iron rule see that no matter how the other player plays, exploitation always yields an advantage; they jump to the conclusion that no more thought is necessary, and play accordingly. This strategy is usually called “All D” (AD) for “Always Defect”.
The Gold rule is the policy of absolute altruism. Gold rule players see that a peaceful society would prevail in the long run; they jump to the conclusion that the long run is already here, and play accordingly. This strategy is usually called “All C” (AC) for “Always Cooperate”.
The Silver rule is the strategy of reciprocity. Silver players do unto others as those others have done unto them. They see that only exact imitation can ensure that the game’s inner logic favors cooperation; they jump to the conclusion that the other player is aware of this, and play accordingly. This strategy is usually called “TFT”, for “Tit For Tat”, which starts by cooperating and continues by reciprocation.
The Gold rule is vulnerable, the Iron rule is vicious, and the Silver rule is vain. Gold is for prey (or host) species, Iron for predator (or parasite) species, and Silver for social (or symbiotic) species. Gold says, “what’s mine is yours”; Iron says, “greed is good”; and Silver says, “value for value”.
There exist many other rules: R for Random play; TF2T, “Tit For Two Tats”, which defects only after the other player defects twice in a row; 2TFT (two-tits-for-a-tat); “angry” TFT (TFT starting in an unfriendly state); TFT with occasional “testing” behavior; and TFT with “forgiveness factor”, which ocassionally (at random) forgives misbehavior on the other player’s part. RTFT, “reverse tit-for-tat”, punishes cooperation and rewards competition; best to punish it at all times! There are hybrid strategies like “two tits for two tats, with testing behavior and forgiveness factor.” All these are variants and combinations of the Iron, Gold, and Silver rules.
The strategy Pavlov is a “kingmaker” program; it culls out the weak. “Pavlov” is nice on the next round if this round truced or drew, and is mean on the next round if this round won or lost. That is, Pavlov repeats its present play if it came out truce or win, and switches if if came out draw or loss. Pavlov is a pragmatic strategy; it repeats only prospering tactics. It has a bottom-line agenda; its rule of thumb is “if it ain’t broke don’t fix it”.
Which strategy is best? That depends on many factors; the other player’s strategy, the replay probability w, the “shadow of the future” SF, and the tactical position of the dilemma game itself. Thus dilemma games have a second level of play; strategic as well as tactical. How to play matters as much as what to play.
Negotiation is possible in Dilemma, unlike in competitive games. Negotiation, strategy, and tactics intermesh in the following two negotiation agendas; “Axial Play” and “The Generous Offer”:
Axial Play: for players at balance.
Tactic; a player limits play to truce-draw “axis”.
The board permits no advantage of one over another.
Strategy; that player threatens draw unless truce.
Appeal to principle. Firmness against exploitation.
This is tactically soft-line cooperative and strategically hard-line competitive. This is the Justice agenda; ethical actions, tough bargaining. It stands on shared principle. It says; “Bribe, threaten, and emulate.”
The Generous Offer: for player in position of strength.
Tactic; the player limits play to truce-win “column”.
The board permits no adverse outcome for player.
Strategy; the player offers to share his prosperity.
Appeal to self-interest. Peace bought and paid for.
This is tactically hard-line competitive and strategically soft-line cooperative. This is the Mercy agenda; tough actions, ethical bargaining. It stands on shared privilege. It says; “Make them an offer they can’t refuse.”
Each agenda requires tactical support (the facts on the board) and strategic negotiation (the offer on the table).