Learning to play nice with other people

It's a dog eat dog world. Every man for himself, no matter the cost. If so, how could behavior such as cooperation arise in the first place?

From evolutionary biology to international diplomacy, we can model many situations using what is called game theory. In these games, actions or strategies are available to each participant, as well as payoffs, which are the positive or negative values ​​that each player gains or loses as a result of each outcome. Some games are zero-sum games, where one player's gain equals the other's loss. Some don't.

One famous game (not zero-sum) is particularly illustrative here. The Prisoner's Dilemma, in its most basic form, involves two “criminals” who are caught and held in separate cells without the ability to communicate.

There is not enough evidence to convict either of the major charges, but enough to convict both of the lesser charges. They are simultaneously offered a deal: testify that the other has committed a more serious crime and be released, while the other will receive three years in prison. But there's a catch: if they both betray each other, they'll each spend two years in prison. If both remain silent, each will receive a year on the juvenile charge.

Each player's payoff can be expressed as the number of years he serves in prison. If both remain silent, everyone's payoff will be -1. If player A betrays player B, A gets 0 and B gets -3. Betray each other and A and B will receive -2 each. How can a player maximize winnings?

Sometimes each player has a strategy that best responds to the other player's actions. This is called a Nash equilibrium: both do what is best for themselves, and both get the best result.

The dilemma is how actions interact if they don't know what the other will do. Imagine that you plan to remain silent. If your opponent feels the same way, you will benefit greatly by betraying. If the enemy plans to betray, you will also achieve a better result by betraying. In any case, your best action is to betray. This is true for both players, so each betrays, and the total payoff is -4.

If both players trust each other and remain silent, the total payoff is -2. The fact that dog-eat-dog produces a worse outcome than cooperation hints at how the latter might arise.

In the famous 1980s experiment62 computer programs played 200 rounds of the prisoner's dilemma. Most importantly, they could make moves based on their opponent's actions in previous rounds. Selfish strategies tended to have worse results than altruistic ones. Successful strategies do not betray first, but do so when the opponent betrayed in the previous game. They were also lenient and returned to silence when the enemy stopped betraying.

Thus, although “pure” game theory leads to a bad result, a little kindness will be able to overcome this. Behave yourself, but don't let anyone take advantage of you. You have game theory to back you up.

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