Economics means that if the theater is on fire, in terms of maximizing personal interests, it is to run out first. If everyone wants to do this, the result will inevitably be that everyone is blocked at the door and no one can run out. Individuals pursue the maximization of interests without considering the interests of others, which leads to staged group tragedies.

The story of "Prisoner's Dilemma" tells that two suspects were caught by the police after committing a crime and were held in different rooms for interrogation. The police knew that the two men were guilty, but they lacked sufficient evidence. The police told everyone: if both people deny it, they will be sentenced to one year each; If both confess, they will be sentenced to eight years each; If two people have a confession, a denial, a confession, and a denial, they will be sentenced to ten years. Therefore, every prisoner is faced with two choices: confession or denial. But no matter how the partner chooses, the best choice for every prisoner is confession: if the partner denies it, he will be released if he confesses, and if he denies it, he will be sentenced to ten years. Confession is better than no confession; If your partner confesses and confesses himself, you will be sentenced to eight years. Confession is better than denial. As a result, both suspects chose to confess and were sentenced to eight years in prison. If both of them deny it, it is obviously a good result to sentence them to one year each. The profound problem reflected by the prisoner's dilemma is that the individual rationality of human beings sometimes leads to the collective irrationality-smart human beings will be trapped by their own cleverness or harm the collective interests.