You’re asking for an example of details that aren’t those of the other guard. If they give you a non-working example, then the lying guard has been truthful. Which is a contradiction.
Consider the question ‘what is an example of something that is not a cat?’. Any answer that is not a cat is truthful; therefore the lying guard must give an example of a cat.
Ah, ok, so to clarity, you could also ask, “tell me anything that isn’t the other guard’s number,” and they have to tell you exactly the other guard’s number.
![Two Guards Riddle. [11]](https://lemmy.world/pictrs/image/d5137530-1a9a-4e36-9cdc-f4de97e02362.jpeg){kind=link}
You’re asking for an example of details that aren’t those of the other guard. If they give you a non-working example, then the lying guard has been truthful. Which is a contradiction.
Consider the question ‘what is an example of something that is not a cat?’. Any answer that is not a cat is truthful; therefore the lying guard must give an example of a cat.
Ah, ok, so to clarity, you could also ask, “tell me anything that isn’t the other guard’s number,” and they have to tell you exactly the other guard’s number.