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TED-Ed Original lessons feature the words and ideas of educators brought to life by professional animators. Are you an educator or animator interested in creating a TED-Ed original? Nominate yourself here »

Meet The Creators

  • Educator Alex Gendler
  • Director Outis


Additional Resources for you to Explore
Find the original paper by George Boolos here. The riddle belongs to a category of puzzles known as Knights and Knaves, many of which can be found in Raymond Smullyan’s classic What is the Name of This Book? For a more in-depth look at these riddles, you can read this overview of the assumptions and possible paradoxes in different versions of the puzzle, or learn more about the law of excluded middle.

Don’t forget that TED-Ed has more riddles! For more fun, start with these three:
Can you solve the river crossing riddle? - Lisa Winer
Can you solve the counterfeit coin riddle? - Jennifer Lu
Can you solve the frog riddle? - Derek Abbott