Prisioner's Dilemma

A prisoner is told "If you tell a lie we will hang you; if you tell the truth we will shoot you." What can he say to save himself? Note that he must say something to save himself.

Answer:

He must say, "You will hang me." in order to escape from the clutches of death. Let us see how this works out. He cannot be hanged because he had predicted correctly and therefore uttered a true statement which calls for shooting him. He cannot be shot also since he had prophecied wrongly that he would be hanged. In either case, the statement uttered by the prisioner has put the authorities on the horns of a dilemma and the sentence can not be logically carried out thereby sending him scot-free.