Lost in the woods, you finally happen upon a rickety old bridge across a deep ravine. The ravine is too steep to go down and climb back up. You need to know if the bridge is safe. As 'luck' would have it, you recognize that on the other side of the bridge is that dreadful town, "Knight-and-Liarville". Everyone who lives there is a knight (who always tells the truth) or a liar (who always lies). You are tired and you've been lost in Knight-and-Liarville before. You see three men on the other side of the bridge.
You shout out: "Are you a knight?"
The first man says something, but you can't hear what he said.
The second man shouts, "He said he was a knight."
The third man shouts, "No, he didn't. He said he was a liar."
Which man do you ask to find out whether or not the bridge is safe?
Everyone seems to be assuming that the first person actually answered the question as asked.
Suppose the first person said "My shoes are blue"
In this case, the second man is a liar as well as the third.
We KNOW the first person did NOT say "I am a liar." Therefore the third person IS a liar. But the veracity of the second person cannot be determined, since we don't know what the first persons actually said.
Only 1 is safe to ask...
