A teacher places three coins in front of her student: 1 copper, 1 silver, and 1 gold. She tells her student, “If you tell me a true statement, you will be given one of the coins. But if your statement proves to be false, you will be given nothing.”
What should the pupil say to guarantee being given the gold coin?
She says: “You will not give me the copper or silver coin.” If this is true, you get the gold coin. It cannot be a lie, because if it were a lie, it would have to come true!