How to Solve the ‘The Three Gods Riddle’, Which Has Been Described ‘Hardest Logic Puzzle Ever’

TED-Ed writer Alex Gendler explains how to solve what he calls the “hardest logic puzzle ever,” the three gods riddle. An astronaut is stranded on an alien world, and to get home they have to correctly identify three alien overlords using only yes-no questions, but without knowing which alien word means “yes” and which means “no.”

You and your team have crash-landed on an ancient planet. Can you appease the three alien overlords who rule it and get your team safely home? Created by logician Raymond Smullyan, and popularized by his colleague George Boolos, this riddle has been called the hardest logic puzzle ever. Alex Gendler shows how to solve it.