generalmercer:

maybe i have a faulty understanding about how this works but like. i never understood the whole “one of us only tells the truth, the other only lies” like…. just ask them a question you know the answer to. what days christmas. the fucker over here going “april 7th” is the liar. problem solved

Because I’m me and kind of a pedant…

The critical third rule to this game is “You can only ask one question total.”  So you have the one who always lies in front of one door, for example, and the one who always tells the truth in front of the other door, say, and then you can ask ONE question that has to tell you everything you need to know.  Generally, if you can get the answer you need, finding out if you’ve asked the liar is a nonissue.

Exempli gratia: in Labyrinth, when Sarah is faced with the situation, she asks one of the two “would the other one tell me that this door leads to the castle.”  When the answer is yes, she knows that the other door leads to the castle and the one she’s facing leads to certain death.  This is because, if the guard she asked was the liar, she knows the other guard would tell her no, this door does not lead to the castle.  If the guard she asked was not the liar, she knows that the other guard would tell her yes, this door would lead to the castle, and it would be a lie.  QED, the other door leads to the castle.  The fact that Sarah falls down a hole does not change this, because she does eventually reach the castle and Jareth is kind of a cheat.  A faerie cheat, but still.

(via lupinatic)