MovieChat Forums > La habitación de Fermat (2007) Discussion > one always the truth one always lies

one always the truth one always lies


a better answer (what single question can you ask to get the true answer if you don't know which guy is which)

"If I were to ask you which is the real exit, what would you answer?"

More elegant than "What would the other guy say if I asked him?" to get the false answer.

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how can it be better if its incorrect?

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Some people don't use their brain.

What is the difference of your "elegant" question with:

"which is the right door?"

Either question don't solve the riddle!

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Wow this is my nominee for the 'dumbest post ever' award.

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[deleted]

I think you (zzz05) misunderstood the situation. Lets say door 1 is the real exit and door 2 is the fake one

"If I were to ask you which is the real exit, what would you answer?"

The truth teller answers "door 1"
The liar answers "door 2"
The trouble is you don't know which one is the liar or the truth teller

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Actually, that's not quite correct, and the OP is right.

Assuming still that 1 is real and 2 is fake:

"Which is real"?

The truth teller answers "door 1"

"If I were to ask you which is real, which would you answer?"

The truth teller answers "door 1"


"Which is real"?

The liar answers "door 2"

"If I were to ask you which is real, which would you answer?"

The liar answers "door 1"


If asked directly, the liar answer "door 2". And if asked about how he would answer, he would lie and say "door 1"

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hmmm well edit: actually according to wikipedia (yes..) zzz05 reasoning would actually work IF you could ask both of them, but you can only ask one question once according to the rules of the riddle spoken in the film (I think?? I forgotten)

wait whats the anwser!

I give up.

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zzz05's post is like a Rorschach test to draw out people who can't reason.

The question zzz05 suggests is in fact the easiest one to use to get the right answer, as both the truth teller and the liar will be "forced" to say which is the correct door. The truth teller will indicate the correct door, because he is only capable of truth. The liar will also indicate the correct door, because he will be "forced" into lying about his usual lying - the double negative that results in the positive (correct answer).

This riddle is millenia old, as is zzz05's solution. Just because you don't understand the solution doesn't make the solution wrong.

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I now understand the reasoning behind zzz05's question, i.e. the liar will lie about lying, and that double negative will give you the correct door.

Both solutions work, but the question "What would the other guy say if I asked him which door was safe?" is the recognised solution to the The Double Jeopardy Doors riddle that this is based on, just look it up on the internet.

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ok, here we go. I'm so glad fblogin works, or I would've made an account for this post only.

Say door 1 is the correct door. lets say you ask the official recognised question.

The person who tells the truth:

What would the other guy say is I asked him which door was safe?
Door 2

You take door 2


The person who lies:
What...safe?
I don't know :D

You're screwed..

This just needed to be added..

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Wrong,because you would know the answer given about which door to choose would be in the truth teller's answer.The one saying "I don't know" would obviously be the liar.Since both know the answer,and only one would lie about it,the one saying he doesn't know would be the liar and you'd get the solution from the other one.

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tane_v_w:

If the liar is allowed to answer the way you suggested, then the puzzle has no solution, period. The answer your liar gives is equivalent to the liar not answering at all by giving any non-sequitir as an answer.

Since your scenario has no solution, it is not worth considering.

So, we're back to the original scenario, and zzz05's correct answer.

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An elegant answer indeed. Although I must admit my first reaction was similar to that of the posters calling you an idiot.

Always ask yourself :"What would Neil Patrick Harris do ?"

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Personally I think avoiding the double negative is easier to understand but I see where you're going.

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what's wrong with the simple questions with obvious answers? like "am i a human being?" the one who lies says no, the other says yes.

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Well you'll find out who is the liar, but you still won't know which door to go through. And you only get 1 question.

http://www.youtube.com/watch?v=1hFvxzTMw6k
The Ricky Gervais version of this puzzle ^

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oh, that's right. So the men aren't tied to the doors. I assumed they were kind of guards.

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[deleted]

After hearing this puzzle it rang a bell to me like i'd heard it before wasnt this the same riddle that jennifer connelly had to answer at one point in labrynth too?

Walter Crewes: God is just an imaginary friend for grown ups.

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Along with the ancient greek meeting the Cretan.

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The real question about this riddle is:

What thought process leads you to either of the correct solutions?

Seems to me it's a huge inductive leap that no one I've ever known has made without assistance, and I've known some very smart people.

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