Sancho Panza, servant of
the Don, becomes
governor of
an island with an odd law: A guard questions every visitor, "
Why are you coming here?" If the
visitor answers
truthfully, he may pass, but if he answers
falsely he is hanged.
One day a visitor answers "I came here to be hanged!" The guard is baffled: If they don't hang him, the visitor has lied, and should be hanged; but if he hangs, he has spoken truth and should not be hanged.
Sancho Panza is called on to decide the case. He reasons that whatever he does will break the law, so he lets the visitor go free on the mercy of the court.
A Blather of Paradoxes