In 1978, American philosopher and mathematician Raymond Smullyan refined an existing logic puzzle to test deductive reasoning, or how well a person applies broad rules to arrive at a specific answer. In his “knights and knaves” scheme, problem solvers must determine the occupations of people on an island based on how they self-identify.
Instructions: There is an island on which all the inhabitants are knights or knaves. Knights always tell the truth, and knaves always lie. Based on the statements, answer the question.
1. You encounter two people: Alison and Bernard.
Alison asserts, “At least one of us is a knave.”
What are Alison and Bernard?
2. Three people approach: Alvin, Byron, and Claudia.
Alvin says, “All three of us are knaves.”
Byron says, “Exactly one of us is a knight.”
What are Alvin, Byron, and Claudia?
3. A trio of island dwellers greet you on the beach: Alicia, Betty, and Clyde.
Two of the group are the same, either both knights or both knaves.
Alicia offers, “Betty is a knave.”
And Betty counters, “Alicia and Clyde are the same type.”
What is Clyde?