User:Anon126/Truthful and Liar Problem
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- Although some may think this is a paradox, it is by no means the case. There is a definite solution.
This is a puzzle about one who tells the truth (a "truthful") and one who tells lies (a liar).
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[edit] Problem
- You come across two doors, with two people (a truthful and a liar), one standing in front of each door. One door leads to the World of Truth(fuls) and the other leading to the World of Liars. The persons stand in front of the respective doors to their world. You want to get to the truthful world, yet you cannot tell which is which, and which person is the truthful and which is the liar. You may ask one of them one question about them to try to tell who's the truthful. The problem is, what do you ask? (assume that they know about each other's honesty, and, to clear up unclear pronoun references, assume (only when reading this) the truthful is a male, and the liar is female (you still can't tell which is the truthful, though))
[edit] Solution
- The most common solution is, "What would the other say about you [whom you are asking] if I asked him [the other] if you told the truth?"
[edit] Truthful's Response
- The truthful would respond that the other would call him a liar. He knows the liar would call him a liar, and, since he speaks the truth, says she would call him a liar.
[edit] Liar's Response
- The liar would say that the truthful would call her a truthful, since she knows he would call her a liar. Since she tells lies, she will say that he calls her a truthful.
