Posted by Mark D. on November 30, 2005 at 22:23:22 from 62.255.32.12 user Whiteshill.
In Reply to: Re: Paradox posted by Robert Dilley on November 30, 2005 at 21:29:03:
The solution is actually to ask one guard "If I were to ask the other guard - which exit would he tell me was the one to freedom?"
If it is the liar then the other guard would have told the truth, but the liar would give the opposite answer - ie he would indicate the wrong exit.
If it is the truthful one then he will tell you the wrong one, because the liar would lie, so again the wrong exit would be indicated.
You should choose the other exit.
(I'm sure somebody else could put this more succinctly!)