• pirc_lover@feddit.ukEnglish
    45·
    16 days ago

    What always bugs me about this in popular culture is that you only get to ask one guard the question, not both. So the question you would ask here would be:

    “If I asked the other guard for a credit card number, expiry date and security code that wasn’t yours, what is an answer they could give me?”

    • schema@lemmy.worldEnglish
      9·
      16 days ago

      Wouldn’t it be easier to just ask something like “is red a color?” To one guard?

      I think the original riddle also had 2 doors and the question was something like “which door would your partner say leads to freedom” iirc, which makes both point to the one that leads to death.

      • pirc_lover@feddit.ukEnglish
        17·
        16 days ago

        You only get one question to one guard. So if you ask ‘is red a colour’, you find out which guard is lying, but not which door is the correct one (or either of the guards’ credit card info)

      • pirc_lover@feddit.ukEnglish
        9·
        16 days ago

        “If I asked the other guard for a credit card number, expiry date and security code that wasn’t yours, what is an answer they could give me?”

        Truth guard: the other guard lies => if asked for details that weren’t the truth guard, must lie => tells details that are truth guard’s => truth guard tells you these correct details

        Lie guard: other guard tells truth => could state any details that are not lie guard’s => lie guard must therefore tell you their credit card info

        So you get one of the guard’s info. You could change it to a specific guard’s info if you’d like.

        • tetris11@feddit.ukEnglish
          11·
          16 days ago

          I guess I’m not getting it. Couldn’t the “that wasn’t yours” part be misconstrued to allow for anyone’s info?

          The truth guard could recite someone else’s credit card (which would still be a win), but the lie guard could fabricate false numbers completely

          • pirc_lover@feddit.ukEnglish
            5·
            16 days ago

            You could rephrase it to

            “If I asked the other guard for an example of a credit card number, expiry date and security code that weren’t the details of the guard I am currently talking to, what is an answer they could give me?”

            if you’re worried about misinterpretation.

            If you were to ask the lying guard for ‘an example of a credit card number, expiry date and security code that weren’t the details of the other guard’, they would necessarily have to give the correct details, which the truth guard would pass on

            If you were to ask the truthful guard for ‘an example of a credit card number, expiry date and security code that weren’t the details of the other guard’, they would necessarily not be the correct details. However, the truthful guard could answer with any incorrect details, and so the complement of the set of details the truth guard could give is only the correct details, which the lying guard would therefore have to give. That’s why you ask for ‘an example’.

            • sem@piefed.blahaj.zoneEnglish
              2·
              15 days ago

              If you were to ask the lying guard for ‘an example of a credit card number, expiry date and security code that weren’t the details of the other guard’, they would necessarily have to give the correct details, which the truth guard would pass on

              Couldn’t they just lie and give you a non-working example?

              Or are you hinging your question on a variation of “don’t tell me the other guard’s credit card information”, which you expect the lying card to contradict and tell you?

              • pirc_lover@feddit.ukEnglish
                2·
                15 days ago

                You’re asking for an example of details that aren’t those of the other guard. If they give you a non-working example, then the lying guard has been truthful. Which is a contradiction.

                Consider the question ‘what is an example of something that is not a cat?’. Any answer that is not a cat is truthful; therefore the lying guard must give an example of a cat.

                • sem@piefed.blahaj.zoneEnglish
                  2·
                  15 days ago

                  Ah, ok, so to clarity, you could also ask, “tell me anything that isn’t the other guard’s number,” and they have to tell you exactly the other guard’s number.

  • Pika@sh.itjust.worksEnglish
    4·
    15 days ago

    an easy cope out: “I don’t know” unless he’s actually memorised the number its a truth, I know I don’t remember more than the last 4 on any of my cards.

  • Wataba@sh.itjust.worksEnglish
    31·
    16 days ago

    The one doing the explaining has to be truthful anyway, otherwise its just a Samurai Jack situation and they’re both liars.

    In the first panel theyre both being truthful. Just sayingm

    • ITGuyLevi@programming.devEnglish
      2·
      16 days ago

      Which goes to say that neither of them ‘always lies’, this version seems a bit messed up in the setup.