The Prisoner's Dilemma

Explained for law abiding people.

Just to be sure, I'll explain the problem in the next two paragraphs. If you are already familiar with the dilemma, you can skip those paragraphs and start ready why this problem is also interesting for non criminals.

The prisoners dilemma is usually described as followed: Two criminals are arested, and are questioned seperately. They can remain silent or betray each other. When a suspect gets betrayed, he will go to prison for ten years. The suspect that betrays the other, will be released as a reward for his services. When they betray each other, they will both server eight years. If they both don't tell on each other, they can be convicted vor just a small fact and they will both serve only two years.

The best option for both would be, to keep both silent. They would get of with a total of four year punishment. The dillemma occures when you look at the options of a single prisoner. If the other prisoner keeps silen, the first prisoner kan get away without punishment, by betraying the other. And if the other prisoner has betrayed the first one, the first one can reduce his punishment, by betraying the other. Regardless of the choice of the other prisoner it's benifitial to betray the other. This is true for both prisoners, they will both tell on each others, and get a scentence of eight years. Much more than what they would have had, if they both would have kept silent.

Well, you can say: "I'm not a criminal, so this problem doesn't apply to me." But this problem has many variants. Suppose you are a programmer. You also have a choice. You can design your software, partion your code properly in resuable functions, objects and other modules. Well document your code and use clear variable names and add comments. Another possibility is to start hacking right away without the use of functions or objects, but copy and paste your code for simular functioniality. Code produced in the last way, is impossible to reuse, but your are finished faster, you don't spend time thinking up a good structure and also documenting doesn't cost you time.

Now you have a colleague. You can both choose: Program clean or a quick hack. If both of you program propper you can share each others code and develop your software quickly. But if you look at your individual result, you reach the following conclusion. When your colleague is hacking and you are programming correctly, you can't reuse his code. He can use your code. His productivity will be higher dan yours. He will get promoted, you'll get fired. If you start to hack in such a situation, both your productivities will be the same. You won't be fired immediately, but your productivity is lower than your competitor's. Your company will go bankrupt, and you are both out of work. If your colleague is a clean programmer, and so are you, you just keep your job. But if you start hacking, you will get the promotion, as most productive programmer.

Also in this situation, you are, like the prisoners, better off if you make a choice, that is bad in the bigger picture. Other examples are: Paying taxes. The amount payed by an individual, is nothing compaired to the total amount of tax revenues. It won't be missed, until everybody stops paying taxes. Also in a war, you can choose not to fight. Here also you individual effort is minimal, until everybody stops.

There are many situations where a choice can be made between egoistical and social behavior In those situations the prisoners dilemma is present. The rational (egoistic) choice seems to be the best for the individual, while the other (social) choice is best for everybody.

There are many situations where a choice can be made between egoistical and social behaviour In those situations the prisoners dilemma is present. The rational (egoistic) choice seems to be the best for the individual, while the other (social) choice is best for everybody.

Force or an appeal to conscience isn't always possible. For a series of this kind of situations, mathematicians have developed an optimal strategy. Which is called "Tit-for-tat". It works as follows: Start social and copy the behaviour of the other immediately. Pay attention to the subtle difference between "Tit-for-tat" and "An-eye-for-an-eye" At Tit-for-tat one must start socially. An other important issue is to reward positive behaviour immediately. Be forgiving, at the first sign off good will, be positive aggain yourself.

Tit-for-tat is a good fundament to live your life: