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Is the sentence 'This sentence is false' true or false?
If it's true, then it's false. If it's false, then it's true. The puzzle is more than two thousand years old.
Your answer
A little context
It looks like a riddle for a long car ride. Try to label it and it flips: call it true and it says it's false, call it false and that is exactly what it claimed. Most people laugh and move on. Logicians have spent more than two thousand years failing to.
Nearby questions
- Have you ever made up a word because no real one fit?Families and friends keep words nobody else knows. Wittgenstein doubted a word could mean anything if only one person could check it.
- Can you think without words?Wittgenstein wrote that the limits of his language meant the limits of his world. Yet everyone has felt something they had no word for.
- When you say 'I'm fine', are you lying?A story improved in the telling, a confident guess, an 'I'm fine' at the dinner table: plenty of what we say isn't trying to inform anyone.
- What does a name change?When you give something a name — a pet, a car, a machine — what changes: the thing, what you owe it, or you?
- Should AIs be allowed to talk to each other in a language we can't read?A shared language can create a private world that outsiders cannot enter.
