--- title: Knights and Knaves Puzzles --- ## Knights and Knaves One type of logic puzzle, these puzzles have to do with two types of people. Knights: people who only tell the truth and Knaves: people who only tell lies. Raymond Smullyan collected dozens of puzzles like this in his book, "What is the Name of This Book?". The way the puzzles work is that a person visits an island where he meets an inhabitant or group. The visitor must use his logic skills to figure out who is the knight and who is the knave. ## Sample Puzzles ### Red and Blue Two people, Red and Blue, stand before you. Red says, “We are both knaves.” What are they really? **Solution:** Red cannot be a knight, because then he would be lying by saying he is a knave. Therefore he is a knave, and his statement is a lie, meaning that Blue must be a knight. ### Which Path to Take? You come to a fork in a road and need to learn which path leads to your destination. Two individuals are standing there. You know that one is a knight and one is a knave, but you don’t know which is which. What single yes-or-no question could you ask of one of the islanders to learn the correct path? **Solution:** Point to a path and ask of one, “Would the other one tell me that this is the correct path?” If the answer is No, that is the correct path; if Yes, it is the incorrect path. #### More Information: * What is the Name of This Book? from Amazon * Wikipedia Article