On an island of Knights (who always tell the truth) and Knaves (who always lie), Arthur says to you: 'My friend and I are both Knaves.' What are Arthur and his friend?
Arthur is a Knave and his friend is a Knight.
If Arthur were a Knight, his claim that both are Knaves would be a lie, which a Knight cannot tell. Thus, Arthur must be a Knave. Because Arthur is a Knave, his statement must be false. The opposite of 'both are Knaves' is 'at least one is a Knight'. Since Arthur himself is a Knave, his friend must be the Knight.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Hard. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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