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I am looking for the source to the riddle that involved two doors: safety/destruction two guards: one always lies/one always tells the truth time for a single question from a single gaurd.

I first heard and solved this riddle when taking philosophy 101: an intro to logic at Ohio State University back in 1983.

I was surprised to find that they had a problem I'd never heard before as there wern't that many good logic proplems going around back then.

Riddles often have clues to their source,ie based on the conservation of matter so the source may have been from a physics professors lecture.

The riddle under question is based on truth tables or possibly multiples of pos/neg numbers

Does any one have any clues to it's source? has anyone heard it before 1983?

thanks

Ankoganit
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TakenItEasy
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1 Answers1

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The common name for such types of puzzles is a Knights and Knaves puzzle (named by Raymond Smullyan in a book from 1978) or just a liars puzzle. The earliest I've found is Mathematical Recreations (1953) by Maurice Kraitchik.

If you'd like to see some more, the tag here has tons of them, including the exact puzzle you described.

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qwertyu63
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