The Hardest Logic Puzzle Ever (and How to Solve It)

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It's that strange time of year, the lull between Christmas and New Year, when you're not really celebrating but not really working either. So, how about you wrap your brain around the world's hardest logic puzzle to keep yourself amused? Y'know, just for fun.

New Scientist has a lovely feature (which is available to read if you sign up for a free account) in its Christmas issue about the world's most difficult logic problem. If you're wondering what could possibly be so tough, check it out:

"Three gods A, B, and C are called, in some order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or falsely is a completely random matter. Your task is to determine the identities of A, B, and C by asking three yes-no questions; each question must be put to exactly one god. The gods understand English, but will answer all questions in their own language in which the words for 'yes' and 'no' are 'da' and 'ja', in some order. You do not know which word means which."


It was dreamt up—and solved—by US logician George Boolos shortly before his death in 1996. What makes it so difficult is it's incredible amount of problems, all squeezed into one puzzle: language barriers, untruthfulness, and randomness, too. Philosophers claims that cracking the puzzle reveals the true nature of logic itself to those willing to toil with the problem—but if you can't be bothered, you can find a (relatively) simple solution here. [New Scientist]

Image by a r b o under Creative Commons license