The Prisoner’s Dilemma and the Tit for Tat strategy

The Prisoner’s Dilemma game is a favorite subject of analysis for theoretical biologists. This game has many versions, one of which can, for example, be described as follows: Two offenders were caught after they committed a serious crime. There is no direct evidence against them so that, if they cooperate, i.e. deny their guilt, no one can prove their main crime and they will be sentenced only for secondary crimes, such as having possession of a stolen object, with a relatively milder punishment, for example, 3 years in prison. The prisoners are closed in their separate cells and each receives the following offer. If he confesses first and designates his accomplice as the principal guilty party, then he will receive only a mild punishment, for example, one year in prison. However, if he denies his guilt, while the other prisoner who received the same offer, confesses first, then he will receive a sentence of many years. However, if they both betray their accomplices, each will receive a sentence of 5 years in prison. In theoretical studies, the game is played for points rather than years in prison. Usually a game is analyzed in which the reward is 3 points for mutual cooperation, 1 point for mutual betrayal and 5 points for the betrayer and 0 points for the betrayed in one-sided betrayal. Mathematical analysis of the problem demonstrates that, under the given conditions, it is preferable for either of the prisoners to immediately betray his accomplice and not expose himself to the risk of being the second to opt for this approach. The course of a large portion of actual interrogation processes indicates that most offenders do not need to be conversant with the mathematical apparatus of game theory in order to find the only right strategy. Situations that are more or less similar to the prisoner’s dilemma are, of course, encountered in nature. An individual sometimes finds himself in a situation where he must choose between betrayal, which can bring great profit or only a small loss, and cooperation, which can bring average profit if the partner also cooperates, but a major loss if the partner betrays him. Under conditions where the two partners will not meet again in the future, or where organisms are involved that cannot recognize or remember their former opponents, both individuals will almost certainly make a choice in accordance with the theory of the “always betray” strategy. A different situation occurs if two individuals play the Prisoner’s Dilemma game repeatedly and are capable of remembering the course of the last game. Then the Tit for Tat strategy turns out to be very advantageous. This consists in cooperation in the first game and then, in future games, always repeating the strategy of the other player in the previous game. In nature (and human society), the same opponents frequently meet repeatedly. Consequently, a strategy similar to the Tit for Tat strategy is often employed.