Solving a Game when Rationality Is Common Knowledge
Man in Black: All right: where is the poison? The battle of wits has begun. It ends when you decide and we both drink and find out who is right and who is dead.
Vizzini: But it’s so simple. All I have to do is divine from what I know of you. Are you the sort of man who would put the poison into his own goblet, or his enemy’s? Now, a clever man would put the poison into his own gob- let, because he would know that only a great fool would reach for what he was given. I’m not a great fool, so I can clearly not choose the wine in front of you. But you must have known I was not a great fool; you would have counted on it, so I can clearly not choose the wine in front of me. —FROM THE MOVIE THE PRINCESS BRIDE