You meet six men on a road side. The problem is that your wallet is mysteriously missing and you can't figure out if these men are truth tellers or not. So you ask a few questions and here are their answers:

Allan: "Fred stole it. Fred also hears quite well."

Barry: "Calvin is a liar. I did not steal it and I know Allan did not steal it."

Calvin: "Allan and Dwayne are both knights. Eddy stole it."

Dwayne: "Allan is a liar. I did not steal it."

Eddy: "Only 4 of us are knights. I did not steal it. I know Calvin did not steal it."

Fred: "I am deaf but read lips. Barry did not steal it."

Who stole the wallet?

P.S. You are sure that all of the men either lie or tell the truth. No one does both.

(In reply to Perception and Reality by Brian Smith)

I was thinking something like that, but it seems that a knight who always told the truth would certainly 'know' if they said they did, the implication of that being that if they know something to be true, then it certainly should be true.

That said, it seems to be the only really plausible explanation (and it would certainly account for the strange title of the problem). If that is the case, Allan or Calvin (incidentally, one of the liars) must have taken the wallet, and somehow Barry or Eddy is mistaken in what they 'know.'

Good observation!

Posted by DJ on 2003-06-10 15:51:45