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Two Doors riddle... (Please don't cheat)

Ed© 2008/10/02 02:43:14
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Please No Cheating!!! This is to see if people actually know the riddle.

There are two doors. You have to pick one door. One door leads to great happiness, the other leads to great suffering. But you don't know which door is which.

However, there are two people in the room. One of them always tells the truth, but one of them always lies. But, you don't know which is which.

You can only ask one question. What question should you ask in order to determine which door leads to great happiness?

These two people can't be moved. You must ask a question.
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Top Opinion

  • Roofusgirl101 2009/06/21 19:20:15
    Yes I know
    Roofusgirl101
    +3
    You have to remember that the TRUTH of a LIE is a LIE, and a LIE of the TRUTH is also a LIE. You have to ask either one of the guards what the other guy would say if you asked him which door was good. The guy who always tell the truth would point to the bad door, and the person who always lies would point to the bad door. so obviously the other door is good. think about it... it makes perfect sense.

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  • veniceparrish 2014/11/30 01:59:43
    Yes I know
    veniceparrish
    I know what this riddle says the answer should be and, on its face, it sounds like it should make sense, but in practice, it doesn't work because, with this theory, it would require that the liar tell the truth at some point - or, that the truth teller lie. For instance, If you ask the liar to tell you what the truth teller would say where the truth teller's door leads, the liar would have to say "to hell," because that's a lie. If you asked the truth teller to tell you what the liar would say where the liar's door leads, the truth teller would have to say, "to heaven," because the truth teller knows the liar would lie and, for the truth teller, that would be the truth. So, with this form of the question, you have no answer. If you asked the liar to tell you what the truth teller would say about where the liar's door leads, the liar would have to say, "to heaven," because that's a lie. If you asked the truth teller to tell you what the liar would say about where the truth teller's door leads, the truth teller would have to say "to hell," because the truth teller knows the liar would lie and, for the truth teller, he would be telling the truth. So, no matter how you formulated the question based on this theory, you still would never get an answer. If you still don't understand this, get two people. Designate one the truth teller and one the liar and play it out.
  • JamesC 2014/08/28 10:11:36
    Please be honest... I had to look up the answer
    JamesC
    Pressed wrong button.

    I did know an answer, but it's not the general one given. If the devil is bound to lie, no matter what, then use his nature against him. Ask both, "Which door do you want me to go through?" The the good one, the devil, will point to the one he DOESNT want you to enter. The good one, the angel, will point to the one he DOES want you to enter.

    The logic is a bit odd because if the bad one would tell the truth due to his lie being detrimental to him, that would present an exception that makes the fact he always lies not absolute.
  • venicep... JamesC 2014/11/30 03:04:22
    veniceparrish
    +2
    This is the ONLY version of the question I've heard that could actually work. Every other version I've heard still leaves me with both guards giving answers that would still not give me an answer.
  • Hamid Jawaid 2014/06/06 12:36:27
    Yes I know
    Hamid Jawaid
    Ask the question to one of the robot: "Does exactly one of you lie always?"
    If the answer is "Yes", then this robot is telling the truth. And then ask the other robot :"Which door is happiness?" and this robot will always lie and give the wrong answer.
    and vice versa.
  • venicep... Hamid J... 2014/11/30 03:04:49
    veniceparrish
    +2
    you only get one question.
  • fiona.w.demon 2012/10/30 00:17:47
    Yes I know
    fiona.w.demon
    which door well the other tell me is the happanies one?
  • sasha khramov 2012/08/20 06:01:14
    Yes I know
    sasha khramov
    You ask either one how many doors are in this room? If one says 2 they are telling the truth and you go in the door they're guarding. If they say any number except 2 you go into the opposite door they're guarding.
  • Potchi Mendoza 2011/10/15 11:06:22
    Yes I know
    Potchi Mendoza
    Just ask them a math question, geez. "What's the answer to 1+1?" Obviously, the guard who always tell the truth will answer "2". If you ask the liar, he'll answer any number BUT "2". ;D
  • Tim H Potchi ... 2012/03/01 04:56:14
    Tim H
    +1
    Your answer makes sense, but you have to realize that you just wasted your question and still don't know which door will lead to suffering.
  • David Quigley 2011/09/12 22:21:08
    Please be honest... I had to look up the answer
    David Quigley
    P1(truth) if I ask p2(liar) if p1(truth) is the liar what will he say? no!

    P1(liar) if I ask p2(truth) if p1(liar) is the liar what will he say? yes!

    I thought of an old movie I once saw called the Labyrinth I was tempted to look up the answer but I actually completed it by drawing it out on paper and thinking about it real hard. I didn't want to look up the complete answer on the internet because it would not be fair to Michelle whom I have claimed I love, I also would be lying by cheating, so I kept my word didn't I?
  • Rayndi Dark 2011/08/26 03:39:51 (edited)
    Please be honest... I had to look up the answer
    Rayndi Dark
    My son was asked this question by his 5th grade teacher and of course we came to the world wide web for the answer! Thanks! Can always find ANY answer on the WWW!!!!
  • Ellie 2010/01/12 20:55:49
    Yes I know
    Ellie
    +2
    Just ask either of them which door the other person would say is the 'Happiness' door. Pick the opposite of what they said

    is that right?
  • yo 2009/09/25 20:43:36
    Yes I know
    yo
    +2
    if i asked the other door which door leads to happiness would he say it was yours? if he says yes pick the other door... if he says no pick his door... work it out :)
  • Roofusgirl101 2009/06/21 19:20:15
    Yes I know
    Roofusgirl101
    +3
    You have to remember that the TRUTH of a LIE is a LIE, and a LIE of the TRUTH is also a LIE. You have to ask either one of the guards what the other guy would say if you asked him which door was good. The guy who always tell the truth would point to the bad door, and the person who always lies would point to the bad door. so obviously the other door is good. think about it... it makes perfect sense.
  • not too sure 2009/03/06 18:19:27
    I have no idea...
    not too sure
    i will just take them both and if i go throught the right door i will kill them both for not tellin me
  • Nicole 2009/03/05 03:01:20
    Yes I know
    Nicole
    If i asked you yesterday which door leads to great happiness, what would you say?
  • paulston416 2009/03/01 06:37:08
    Yes I know
    paulston416
    you asked one of the door, "if you were of the opposite doors which one would say is telling the truth.
  • rappingtiger 2008/11/05 23:31:49
    No, I don't know the answer but will guess or I am clueless
    rappingtiger
    i think what i would do is kick both in the lower parts(balls) and laughing my head off while they roll on the ground asking them both if it hurt. The one that says "No." is lying ,because everyone knows that that would hurt, and the one that says "Yes." is telling the truth. Then i would go through the door(the one who says "Yes.") and while going through the door i would say "Sorry." to them both. Ta Da.
  • aMiN 2008/10/16 14:21:38
    Yes I know
    aMiN
    simple....

    just ask one of them... "if you are him (pointing to the other person) ...which door leads to great happiness....")

    then enter to the other door... then you'll be happy.. heheh ^^
  • thewrit 2008/10/04 17:04:34
    Yes I know
    thewrit
    when you get there, pick one, spank him and say:

    "its simple, i will carry you with me. which one are we going?"
  • spanky♥ 2008/10/04 16:30:11
    I have no idea...
    spanky♥
    ....heehee
    i cheated lol
  • MaggieRae17 2008/10/04 05:13:12
    No, I don't know the answer but will guess or I am clueless
    MaggieRae17
    I would ask the both of them, "Tell me what the other would say to the question of which door leads to great happiness?"

    And there ya go. It works.
  • Luna Avis 2008/10/04 03:42:00
    Yes I know
    Luna Avis
    well i would ask what color shirt i am wearing
  • Caitlyn 2008/10/03 10:50:01
    No, I don't know the answer but will guess or I am clueless
    Caitlyn
    Who is happy?
  • Josh 2008/10/03 06:27:17
    I have no idea...
    Josh
    I don't know, but have you heard this one, it's kind of similar...

    You're on an island with to different villages. One village has cannibals that always lie, the other has a friendly tribe that always tells the truth. You come to a fork in the road, one way leads to the friendly village, the other leads to the cannibal village. There is a man standing at the fork, you don't know if he is a cannibal or friendly. You can only ask one question. What do you ask to insure you go to the friendly village?
  • Courtney Michelle <3 2008/10/03 00:45:28
    No, I don't know the answer but will guess or I am clueless
    Courtney Michelle <3
    +1
    umm i guess i'd ask both which door leads to happiness and pick the opposite one
  • Dave Sa... Courtne... 2008/10/03 02:15:19
    Dave Sawyer ♥ Child of God ♥
    +1
    Wouldn't they both give you different answers?
  • Courtne... Dave Sa... 2008/10/03 02:17:02
    Courtney Michelle <3
    +1
    idk probably
  • cappsy has a barcode ~_~ 2008/10/02 20:15:15
    No, I don't know the answer but will guess or I am clueless
    cappsy has a barcode ~_~
    I have no clue
  • Yes I know
    †Eye of The Storm† †Demon†
    i would ask can i have 2 more question
    then i would ask to see some i.d
    and then after i should have figured which one tells the truth so i would ask him which door leads to the eternal happiness
  • cccoke 2008/10/02 14:08:38
    No, I don't know the answer but will guess or I am clueless
    cccoke
    +1
    Ask both and go to the other door ?
  • Ed© cccoke 2008/10/02 14:17:34 (edited)
    Ed©
    +1
    Good morning future Granny

    No thats somewhat close...

    Just ask either of them which door the other person would say is the 'Happiness' door. Pick the other one and you're in good shape.

    The reason... is this...



    Let's assume that the door on the left is the door leading to happiness. The liar would say about the honest person... He would say its on the right. Why? He has to lie.

    The honest person would also have to say that the other person (that being the liar) would say its the right door.

    Either way they would both have to say he would say its the right door. So all in all the left door is the door leading to happiness.

    So just pick the opposite door than what they say.
  • cccoke Ed© 2008/10/02 15:18:49
    cccoke
    +1
    Good morning to you. Did you sleep any last night ?
    I was almost right lol
  • Ed© cccoke 2008/10/02 20:20:01
    Ed©
    +1
    lol ... Yes I slept... From what was it... roughly 12 to 9ish
  • cccoke Ed© 2008/10/03 00:09:25
    cccoke
    Sounds like me lol Hubby woke me up.
  • Ed© cccoke 2008/10/03 01:45:48
    Ed©
    +1
    lol... I had to go to school. and now it's late again lol
  • cccoke Ed© 2008/10/03 01:50:14
    cccoke
    +1
    LOL How do you like my pic ? That is Cricket.
  • Ed© cccoke 2008/10/03 01:53:06
    Ed©
    +1
    This is finally your dog? He is a cutie... Oh I never told you... Our family got another dog... It's a Jack Russel Terrier... He's adorable.
  • cccoke Ed© 2008/10/03 01:57:06 (edited)
    cccoke
    +1
    He is a She lol
    Does your terrier jump all the time ? My sister-in-laws dog does all the time
  • Ed© cccoke 2008/10/03 02:00:40
    Ed©
    +1
    OOPPS.... Don't tell her I said that lol... It's always first nature to say he... Cricket is a very interesting girls name... I have a story book about a bug named Cricket. I just have to think if she was a cricket.

    The terrier hops a lot... He looks like a bunny. We named him Sam. I'll have to post a pic eventually.

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2014/12/17 23:10:29

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