Crawl Across the Ocean

Tuesday, August 03, 2010

62. The Evolution of Cooperation (part 2 of 2)

Note: This post is the sixty-second in a series about government and commercial ethics. Click here for the full listing of the series. The first post in the series has more detail on the book 'Systems of Survival' by Jane Jacobs which inspired this series.

This post is a continuation of last week's post which began discussing The Evolution of Cooperation by Robert Axelrod and covered the first 6 chapters.

In chapter 7 Axelrod provides advice for how people should act if they are in a position where, rather than accepting that they are in a Prisoner's Dilemma and trying to choose the best action based on their situation, they can try to change the situation.

Axelrod notes that while in most cases people will want to influence the situation to encourage cooperation, there are some cases (such as when businesses collude, or in the original Prisoner's Dilemma when the interrogator was trying to get the Prisoners to rat on each other) where the goal will be to discourage cooperation.

So the following advice is for encouraging cooperation in the Prisoner's Dilemma - if you want to discourage cooperation, do the opposite.

1. Enlarge the shadow of the future.

What this means is that interactions between people should be structured so that the same people meet repeatedly rather than meeting a different person every time. It might also mean setting things up so that interactions are more frequent and spaced closer together in time. Basically any change that increases the potential risk of suffering retaliation if you choose to defect rather than cooperate with someone.

2. Change the payoffs

The bigger the payoff for defecting, the greater the temptation to do so. So reducing the payoff from defection or increasing the payoff from cooperation makes cooperation more likely. For example, the potential of an audit, helps encourage people to do their taxes accurately

3. Teach people to care about each other

This is really just another way to change the payoffs. If you care for the other person's wellbeing as much as your own, than their can never really be a Prisoner's Dilemma. And every increase in empathy reduces the element of dilemma in the situation.

4. Teach reciprocity

If people turn the other cheek and forgive each other 490 times or more, then this just allows people who exploit the suckers to prosper. If people repay kindness with kindness but also defection with defection, then this will help keep down the population of defectors and exploiters.

5. Improve recognition abilities

If you don't recognize the person who defected on you last time around, you won't be able to exact your revenge this time around. If you can tell ahead of time whether someone looks like a cooperator or a defector then you can be much better off rather than going in blind.

In Chapter 8, Axelrod looks at some ways in which a basic scenario of
randomly occurring interactions can be modified.
4 different types of 'structure' are considered.

1) Stereotyping - stereotyping means that you judge people based on some easily obesrvable characteristic such as the colour of their skin. Axelrod points out that these sorts of stereotypes can be self-reinforcing. If a blue person expects to be poorly treated by a green person (and vice-versa) then they have no reason to cooperate and will defect against each other. This defective behaviour then reinforces the notion that those blue/green people never cooperate. While this has negative consequences for everyone in that opportunities for cooperation are missed, it also has particularly negative consequences for whichever stereotyped group is in the minority since they will face a lack of cooperation from a majority of the population.

2) Reputations - Axelrod points out that it is good to have a reputation as a bully (someone who will respond to any defection with a very heavy retaliation) since that will scare people into cooperating with you. The hazards of establishing this sort of reputation is that you must pass up opportunities to engage in cooperative behaviour with people by forgiving them for their past transgression. And if more than one person is trying to establish a reputation as a bully, this can lead to a long series of defections until one gets the upper hand.

3) Government - The government needs to design the payoff structure such that most of the citizens will comply on their own. Punishment is generally reserved for setting an example of the few people who do defect and reassuring people that other people are getting away with breaking the laws. Once enough people began to ignore a particular law, because they don't respect the legitimacy of the law and the punishment/reward payoffs aren't set correctly, then enforcing compliance becomes extremely difficult because the cost is simply too high to physically coerce a large percentage of the population and the law tends to break down (see Prohibition, War on Drugs, Marijuana).

4) Territory - Axelrom segues from talking about government to talking about territory by noting that, 'an interesting characteristic of governments that has not yet been taken into account is that they are based upon specific territories.'

Axelrod develops a formal territorial model in which each participant in the situation has four neighbours, one to the North, South, East and West. Each round, a participant plays a repeated Prisoner's Dilemma against the four neighbours and is assigned a score based on their combined result against their four neighbours. Then for the next round, if a participant finds that one of their neighbours did better than they did, they switch to using their neighbours strategy. In this way, successful strategies can spread throughout the population.

Axelrod finds that in the territorial model, it is at least as hard (or harder) for a new strategy to invade a population using a given strategy (as compared to a mode where people meet randomly). If a strategy is stable (resistant to invasion by other strategies) in a population that mixes randomly, it will be stable as well in a population that is organized territorially.

Another finding was that in a territorial model, where people imitate their best neighbour, strategies that do really well in some situations and poorly in others tend to do better than they would in a model where people mix randomly. The territorial nature of the model means that you end up with a greater diversity of strategies in certain areas, and this allows the inconsistent strategy to thrive and convert its neighbours in the areas where conditions are suitable, while dying away rapidly where conditions are unsuitable.

Chapter 9 is a conclusion which basically just recaps everything that has
come before.

The quick summary of Axelrod's results is that, cooperation based on reciprocation (e.g. tit for tat style behaviour) can get started and can thrive in a wide variety of environments and that it withstand attempted 'invasions' by uncooperative strategies. Furthermore, the people doing the cooperating don't have to be friends, they don't have to possess foresight and they don't have to be rational. These characteristics might help, but they are not necessary as shown by the evolution of cooperation between enemy soldiers on the front in WWI, cooperation between bacteria and so on. Furthermore, neither altruistic behaviour nor a central authority is required to maintain cooperation (at least in Axelrod's model where people still retain the capacity to retaliate after someone has defected against them).
Axelrod notes that Prisoner's Dilemma situations ...

As always, there is far more to the book, then I covered here. The Evolution of Cooperation is noteworthy for the clear prose of the author and the thorough take on one particular type of interaction, the repeated Prisoner's Dilemma with two participants. I recommend anyone interested enough in the topic to have made it to the end of this post, should read it for themselves (if they haven't already).

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