If one of them says this whole line then he gives away that he's the one that always tells the truth, because the liar would have to lie about how it works. Similarly if the liar says one of us 'always' lies, then he just told you that he doesn't always lie. But if the liar says that one of us always tells the truth, then neither of them will always tell you the truth.
For those who didn't understand: Asking what door the other guard would tell me is safe, always leads to a false answer. If we ask the liar guard ¿What would the other guard say, if i asked wich door is safe? The liar guard would point to the damger door, since the other truthful guard would do the oposite. If we make the same question to the truthful guard, it would answer as the liar, and also point at the danger door. Thus, asking ¿What would the other guard say if we asked wich door is safe? always has the danger door as an answer. This way, we know wich is the danger door, and that the remaining door is the safe one :D I hope this explains it more concisely
You include both the guards in the question since each have 50% chance of telling a lie, together they have 100%. So you get the wrong answer of whatyou ask. If you ask for safety you are pointed towards danger. If you ask for danger you are pointed towards safety.
@@NovaBoiii Just finding the liar doesn't mean you've found the door that leads to safety. It was never established that the liar automatically guards the danger door and vice versa.
The words I've ever heard actually addressed to a newborn were, 'Breath, baby breath!' She was my daughter and she breathed just fine, as soon as she felt like it. :)
Ahh, but what if you pushed the liar guard through the safe door, and he fakes the screams of death, thereby tricking you into going through the danger door?
I see a lot of people not getting the riddle. Part of this is because it's horribly explained in the video. First off, the guards can't speak except to answer one question (not one question each). So the instructions to the riddle have to be given by a third party, or a message on the wall or etc. Second, this riddle involves two riddles in one, really. You have to determine which guard is lying, and which door is safe, and you only have one question. By asking either of the guards "which door would the other guard say is safe", you solve both riddles in one question. In either case, whether you ask the liar or the truthful guard, and no matter which door they guard, they will always pick the same door. So you can ask either guard the question and choose the opposite.
Finally, after all these years, that episode of Yu-Gi-Oh now makes perfect sense to me. Ever since watching that episode I thought it was madness but alas it was shear brilliance and you explained it so simply and elegantly. Well done ✅.
This puzzle becomes next level when there's only 1 door 1 guard and he lies half the time but you get 3 questions to figure out weather it's currently safe to walk through the door.
The key factor that you omitted is that each guard knows that the other guard will respond in the opposite way. There are actually two ways of asking this question, you can ask about the door that leads to death which will reverse your response based on a yes or no answer. So there are two ways of asking this with 8 possible scenarios.
@@RectanerTreadway no because they have to lie, if they double bluff or lie about lying they would be telling the truth by default and also second guessing the lie
You find a way to make them both say the same answer, IF they do so, then you know it's the opposite. The truth teller will accurately predict which door the liar will say is safe and that is always the danger door, and when that prediction matches you know that the liar was lying and that it's the opposite door. Remember you're not asking them each which door is safe, you're asking them which door they think the other will say is safe. By doing so you know that the truth teller will out the liar by correctly predicting his lie.
You can also ask a hypothetical: "If I asked you if this was the door that leads to death, would you say yes?" If it is the door that leads to death, truthful will say yes, but liar will also say yes, because he is lying about the answer he would give you (a double negative) - "Yes, I would tell you yes (not true), this is the door that leads to death," getting him to lie about his lie has forced him to tell the truth. The same works in front of the safe door, where the same question will make both of them say no.
The classic problem has one unstated assumption, namely that the guards both know about the other being either truthful or a liar. If they didn't know each other, the truthful guard would truthfully answer "I don't know which door the other guard would tell you is safe" while the lying guard, it seems, could not give any logically coherent answer to the question.
Basically the point of the riddle is to make a question that would result in the same answer from any of the guards. And at the same time this question gives us the answer to the riddle. So the only way to do it is to "connect" the guards to each other by the question
I loved this conundrum when I was nine years old. I didn't do too well at school but then I did very well in my university entrance exams and went on to graduate from a top university with a GPA of 3,8....I did well at high school with lateral thinking problems ....I wish that I had had more confidence in my intelligence when I was at high school.
Thought of my own question to ask: Ask guard 1 if their door is safe: they say their door is safe. Ask guard 2 if guard 1 just said that their door is safe. If guard 2 says yes, you can tell guard 1 is lying because both can’t be telling the truth, and if guard 2 says no, you can tell guard 1 is telling the truth because guard 2 would be telling an obvious lie.
There is confusion over the rules of the game on how many questions can be asked and how many guards get to hear the question(s). However, you can still find the safety door by asking only ONE guard ONE question: *"Would it be a lie if your told me this door leads to safety?"* *(1)* If the "truthful guard" was standing in front of the *danger door,* he would say "Yes" because he cannot lie. ... You then opt for the other door. *(2)* If the "truthful guard" was standing in front of the *safety door,* he would say "No" because he cannot lie. ... You then opt for that door. *(3)* If the "lying guard" was standing in front of the *danger door,* he cannot say "Yes" because he can only lie. Based on your question, he would be telling you the truth because it would be a "lie" to tell you that the door leads to safety. *(4)* If the "lying guard" was standing in front of the *safety door,* he cannot say "No" either because he can only lie. Based on your question, he would be telling you the truth because it would be a lie to tell you that the door does not lead to safety. ... Based on the wording of your *one question to one guard,* only the "truthful guard" can even offer you an answer! Based on the wording, the "lying guard" is forced to tell the truth either way - to which he is not capable of doing.
By asking any guard what the other would say, you guarantee a lie. Either by asking the liar directly, or by having the honest guard tell you the what the liar would say.
Rules: Guards are identical, although technically this does not matter for our logic, it helps to envision them this way to grasp the set of variables in this equation. Only they know who is the Liar and who is Truth. Only they know who is guarding the passage to paradise. It is not at all guaranteed that the Liar guards hell, nor that Truth-teller guards paradise. You must also basically assume that the Liar intends to see you pick “the bad door” because in the roles of this puzzle, your own role is defined as you intending to pick the “good” door i.e. "Get out of the Dungeon". The conceit of the puzzle is that having a Liar involved at all presents the main conflict for us. We must neutralize this conflict somehow. The goal is not to *fixate* on the liar and figure out who is who; the goal is to formulate a question that *reduces* the odds. A question that makes all the variables "non-randomized" but a better way to state this is, "to make all these variables incriminate the same culprit". Game: Scenario to prove the theory Theory 1 - Honest guard in front of Hell. (To be known as Door U for Undesirable in our process of elimination. The door to paradise will be known as Door Y for YES.) You can’t just ask the Honest-Guard if he’s guarding paradise because you must assume that he could very well be lying. And you can't just ask him "what am I wearing?" or something redundant, because even if you prove that he's a liar, you still haven't proved that he is guarding the door that you need to select. So, here we are, there's two inscrutable guards in front of two indiscernible doors, and I have no choice but to decide randomly who to ask a single question. A. If I end up asking the HONEST guard “what would the other guy tell me to pick” he’d tell me *honestly* that the “other guy” would tell me *dishonestly* to choose his door aka Door U. -- This is logical because he's telling us that the Liar would want us to choose Door U (which both guards know as being Hell, and the Liar is interested in foiling our plans because I guess our enemies hired him to do that). B. If I end up asking the LIAR (still unbeknownst to me his credibility) and ask same question "what would that other guy tell me to pick", he would default to his duty of lying, and tell me *dishonestly* that the other guard would "Pick His own door" aka Door U, again. Theoretically, this is dishonest because all we are allowed to assume via our theory is - that whoever the honest guard is, he would never advise us to pick Door U if we asked him directly. In other words, we need to assume if the honest guard is ever asked "what door should I pick" he will always tell us "the truth" aka technically "our truth" aka "the thing we want" aka Door Y. While we cannot actually prove on-the-spot that the liar is lying, the phrasing of the question against the available facts allows us to eliminate 1 perilous door from our choices, no matter which guard we end up asking. Because the fact that the liar will exclusively provide misinformation is exactly what our clever question is taking advantage of: It's this process of elimination which means that "a second question" is not required. It is true however, that in the reality of this scenario, order to pick the right door, you MUST first ask the question. The question is required because it helps us receive more concrete data, and it's only with that new data can we THEN make our logical deduction. Therefore via the process of elimination which is now possible, you can determine that the other door, aka the only other door in front of you aka Door Y; is your remaining selection. So to summarize; in both instances, Door U is alleged as the door to choose. No matter who I end up posting the question to, in both cases Door U will be alluded to, because in both cases the Liar will be responsible for tainting all the available data, giving you the opposite of what youre searching for. Knowing this, you also deduce that you must choose the opposite door from what is told to you "as conjecture", after asking that question which theoretically forces either of them to acknowledge an opposing factor, and thus both will indicate the exact same door.
Basically the answer is this: the guard that tells the truth would give you the answer of what the other guard would say which is the wrong answer since the other guard is a liar and the one you asked is the truthful one. In essence, he’s giving you the answer of what the other would say. The guard that lies knows the other will tell the truth and since he lies he will give you the wrong answer as well because he’s a liar and that is not what the other guard would say. In conclusion, the answer will always be the opposite of what the guard said, no matter which one you ask.
I can't! I really can't! People not understanding this even after the explanation just blows my mind away. It literally took me 5mins to solve this. Seems like critical thinking, following simple rules and use of logic is not a thing anymore. You can ONLY ASK 1 question to ONLY 1 of the guards. So, you ask one of the guards (doesn't matter which one) something like: "If I were to ask the other guard which door is the correct one, what would he answer?" If you ask the truth teller, he's gonna tell you the wrong door (because that's what the liar would answer). If you ask the liar, he's also gonna tell you the wrong door (because that's the opposite of what the truth teller would answer). By knowing this, you don't need to ask the question to both guards. You don't even need to know which one is which. Since the outcome is the same in both scenarios, the other door will always be the correct one. Side note: Asking for the wrong door, would also work, in that case you'd pick the same door as the guards. Literally the same, but reversed.
Simpler way to think about this is that the spoken answer contains what either guard would have answered on his own, in other words... the spoken answer IS ALWAYS A LIE because one of them is a liar, we simply guaranteed that the lie is always in the spoken answer.
Simple solution: “Is the lying guard in front of the door to safety” Honest guard in front of door to safety: No. Honest guard in front of door to death: Yes. Lying guard in front of door to safety: No. Lying guard in front of door to death: Yes.
@@JustSomeKittenwithaGun I don't get it. -Edit Ohhhh. It's not about knowing who the lying or truthful guard is, but the answers they give. "No" leads to safety. Appreciated~
@@lusterlessnova3199 I'll try to give my understanding of their comment so you'll hopefully understand it better. If either guard said no, you should go through his door regardless as the other comment described. If either said yes, go through the opposite door. Why? Remember, you only need to ask that one question to ONE guard only, but this still works if you're allowed to ask them both the same question. “Is the lying guard in front of the door to safety?” Guard says NO: If they're the liar, the actual truth is "YES". The other guard MUST say no as well because otherwise there would be 2 lying guards. You can safely go through this door. “Is the lying guard in front of the door to safety?” Guard says YES: If they're the liar, the actual truth is "NO." Again, the other guard MUST say yes or he'd be a liar as well. Go to the opposite door of the guard you asked. Basically, you know which guard is lying because this question is really good and non-contradictory. However, this is a contradictory question IF this condition is met: If you asked them this specific question and one guard said yes, but the other guard said no it contradicts this question and this forces the truthful guard to lie. Understanding this potential paradox is pretty helpful in understanding the solution. If they both were to say no (or yes) at the same time to the question, then we know for a certain it isn't contradictory. Well, I hope this didn't confuse you even more. I had to think pretty hard about it too.
How would this question lead you to know which door is the safe option? With this question you only know who is lying and who isn't, and as you only have one question, this doesn't answer which door is safe
@@tigrenaranjo”you can ask one of them only one question” is not violated by asking them to answer two different questions, one each. his solution asking the same question may be more elegant, but mine’s cleaner, and he didn’t state that limitation in the prompt as clearly as when he’s working through it. he arguably violated his own prompt if you’re going to be that pedantic, since he had to ask both guards a question anyway.
@@tigrenaranjoalternatively, you can also figure out the answer to this general riddle with one question if you’re listening carefully and given the prompt by one or both of the guards. the one who says they are guards or guarding a door is 95% the truth-teller unless they’re not actually guarding anything.
@@kazekagekid I think the implication is pretty clear you could only ask one question, to only one guard, to determine which door is safe, and the answer he gives in the video does not violate his rule; he simply demonstrates the answers each guard would give for each scenario to cover the possibilities, and that no matter which guard you ask or which door they are in front of - you only need to ask one of them and always choose the other door as the safe one.
Me: *Tosses c4 onto both of the guards quickly then pulls out the detonator* "I'm going to push this detonator and blow you both to smitherines unless both of you point to the safe door." No need to ask a question.
Everyone seems to not realize they give themselves away without needing to ask a question. Let me explain. The first one says "One of us speaks nothing but the truth." This is a true statement so whichever says this is the one who tells the truth. Hence why the liar can only say the statement " The other nothing but lies." This one is calling the other a liar as to still abide by only telling lies. So he is the liar. Simple and easy. just ask the one who told the truth which door is safe.
Not really... ...The first one says "One of us speaks nothing but the truth." The liar could be saying this about himself, lying like always. The other then says "The other, nothing but lies." This then would still be a truth by the truth teller.
@@bugoobiga But that's not what they say. It's always one of us always tells the truth and one of us lies. The riddle is supposed to have a third party, or a note on the wall, or something like that, with the instructions, so the guards don't talk unless you ask a question. In this scenario, the OP is correct, the doors cannot give the proper answers. Both doors would have to state "We both always tell the truth".
Ask one guard, "If I ask the other guard if this door leads to safety, what would he say?" Way I have it figured, if the guard says "yes" then the door leads to doom, and if the guard says "no" then the door leads to safety.
There’s the possibility they’re both a couple of psychopaths who are making it seem like your only way forward is one or the other door, when both actually lead to your demise and you were just supposed to continue down the hall to the exit.
One gripe ive always had with this puzzle is what if the liar guard just tells another lie? For the question presented: "what door would the other guard tell me to go through?" The liar guard could just say "he wouldnt answer." Which is a lie, and you dont get any information.
You ask 1 guard an absolute fact like: Am I a human? Case 1: Honest Guard : Yes Now i know that this is the honest guard, then the other must tell a lie Go to the other guard, and ask “Will I die if i go behind this door?” Liar Guard will answer yes or no. Make your decision on the opposite of his answer. Case 2: Liar Guard: No Now, i know that this is the liar guard. Go to the other guard, ask Will if die if i go behind this door? He will tell the truth so do as he says. I followed the rule of asking only 1 question to both the guards each
The rules are not supposed to be given by the guards. A third party is supposed to tell you the rules, or they are displayed by a tablet, scroll, or message on the wall. The guards can only speak to answer one question.
A mistake many riddlers make is when they state the puzzle, they have one of the guards as the speaker. This breaks the rules of the riddle unless the truth guard is the speaker... which also breaks the riddle.
To the people who just want a logical truth like 1+1. You get no info about the door in that scenario you only find out who lies, but don’t get a second question to answer the door problem
Just ask a guard if they are alive. Liar says no, truthful one says yes. Basicly you need to afk them a question they xan wriggle outfrom a question so obvious that the guard cant bank on symantics in your question
The Barbarian raises his axe and kills the first guard. He grabs the second guard and asks “Is he dead?” The guard says “No.” The Barbarian turns to the wizard and says “This one liar.”
Paused to answer... You ask either one of them the question "what would the other person say if i asked them what door they were guarding?" Whichever answer you hear is the answer to the door that the person you asked the question to is guarding.
Example, guard A always lies and is guarding the safe door. Guard B always tells the truth and is guarding the dangerous door. You ask guard A "What door would guard B say he is guarding?" Guard B always tells the truth, and he is guarding the dangerous door. The truth is that guard B is guarding the dangerous door. Guard A has to lie, so he will say "Guard B would say that he is guarding the safe door." Guard A said "safe door." Same question to guard B. Guard B always tells the truth, but he knows that guard A always lies. so when you ask guard B "what door would he say that he is guarding?" Guard A would say "he would say that he is guarding the unsafe door." Remember, guard A is guarding the safe door, but he always lies so he would say the dangerous door. Guard A knows that guard B always lies so would say "dangerous door". Guard B said "dangerous door" so we know he is guarding the dangerous door.
"is it true that one of you always tells the truth, the other one always lies?" if he says "yes" do the opposite of the other guy if he says "no" do what the other guy says.
If there was one guard named Kairos Fateweaver, ask him any questions and he would will give you three answers, all of which are true, and horrifying to know."
the fact that you have to ask them what the other guardian would say makes too much sense if you think about it for a while... it's too easy, but not very well known yet.
yup; we know there is always a lie in the answer, the truthful dude won't affect it. the question has to include what both dudes would answer and there we go.
Ask first guard, “what is 1+1” This determines which one is the liar. Then ask the other guard which door is safe. Since you know which guard is the liar, you know how to interpret his answer. Bingo
But isn’t the only way they could admit that there’s one truth teller and one liar false? Because if the liar is saying “the one of us would speak only lies” that would be telling the truth. The only way they could both make that statement is if they were BOTH lying.
Nah if you asked "what would you say is the safe door if you were the other gaurd?"it doesn't matter who you asked because they would give you the same answer. Then you just choose the opposite of that answer.
@@natas9967 Guard A always lies and stands before door X. Guard B tells the truth and stands before door Y. You don't know whether X or Y is the good door. The riddle assumes that the truthful guard will point at the good door. If you ask the liying guard what the other guard would choose, he would lie and point at the wrong door. If you ask the truthful guard what the other guard would choose, he would tell you the truth and point at the wrong door. Therefore, no matter which guard you ask, you always get your answer. You choose the other door since both guards will point at the 'bad' door. Hope this helps :)
Both the guards want you to think the other is true to kill you, if you ask "would he tell me to go through door 1" and they say yes its because they want you to think the other guard would send you to your doom
You can ask one of them only one question but your solution is to do the opposite of what they agree? How do you know what they agree if you can only talk to one? DOESN'T MAKE SENSE
when you ask "what would the other dude answer" -kind of question you get both lie and truth in the spoken answer, the truth won't modify the lie it remains a lie so now you sneaked the lie to always be in the spoken answer. Since you know the spoken answer is always a lie you just take the other door.
You are wrong. You ask one guard "what would the other guard say is the safe door?" and then you do the opposite of whatever answer you get. Just one question.
@@TheFilipFonky Actually, OP is right. If you listen to the video at 3:00, the narrator clearly says “you have to do the opposite of what they agree on”. But in order to know what the guards agree on, you have to ask 2 questions. So this question is somewhat flawed.
@@tohian the narrator here is implying that they would *theoretically* agree on the same door if asked the same singular question. in other words, you only need the 1 question to prompt them both into giving you the same response meaning no matter who you ask, you can safely assume what the other will say
No need to over complicate it. Ask which leads to safety. Simply ask which one leads to certain death. You don't ask which door is safe. If you ask the liar does this lead to certain death he will say no. And it it is the Truthful gaurd he will say yes.
That’s the catch, you only get the one question. After you figure out who the liar is, you are out of questions and will never know which door is safe.
Ask one guard what's 2+2 If he answers 4 then the other guard which door is the dangerous one and go through that If the guard respond incorrectly then ask the other guard about the safe door and go through that
Easy puzzle just ask if i was to ask the other guy what door to go though what would he say. then u just do the opposite of whatever they say since both guards would agree on the wrong answer.
It's just showing what would happen per scenario. If you asked the liar if his door was safe, (and it waa dangerous) he would say yes. The same would happen to the truthful one.
You will learn who is the liar, but not which door is safe. The trick with this question is you only get one, and need to determine which door is safe with that limitation. This video is poorly structured, so its easy to misunderstand like I did initially.
If they tell you that you can only ask one question, you can solve it in one move by asking one of them "What will the other guard tell me is behind his door if I ask him?" If you are asking the truthful one, it will be the opposite of whatever he reports because the truthful one takes into account that the liar will indeed lie. If you are asking the liar, it will be the opposite of whatever he reports because the liar will give you an inaccurate account of what the truthful one will say. So, if the answer is (bad thing), go through the other guard's door. If the answer is (good thing), go through the door behind the guard you are asking.
Pick a door, and ask them: Will you say this door is safe? 1. The door I picked is safe: 1a. The honest guard: Yes 1b. The lying guard: (I would lie and say that door is not safe, but then I also have to lie about the fact I would lie and say that door is not safe) Yes... 2. The door I picked is dangerous: 2a. The honest guard: No 2b. The lying guard: (I would lie and say that door is safe, but then I also have to lie about the fact I would lie and say that door is safe) No...
I read a riddle about this sort of thing many years ago, and the answer is much easier than you make it sound! You just go up to one of the guards and ask "If I were to ask you if this door lead to safety, would you say yes?"
The trick is to have both guards answer the question, this is done by asking either guard what the other would answer.. now you would know that the answer always has a lie in it. If you ask: "which door would the other dude say is the safe one?" or "would the other dude say THIS door is safe?" .. whatever the answer is, you know it's going to be a lie.. so you take the other door and go watch netflix and chill.
@@n00blamer Think about it! If I ask the liar who is standing in front of the death door, "If I were to ask you if this door leads to safety, would you say yes?" His response is always a lie! If I ask him if he would SAY yes, He would lie about the response he gives, so he would say "NO!" thereby revealing the truth about the safety of the door!
@@JonCox-hp4fw .. and if you stand in front of truth door with life behind it, he would say YES.. so how you know which door you stand in front of? You need to be certain that the answer has a lie so that it can be cancelled out, only way is to format the question in a way that both doors contribute. "what would the other guard say about this door", then either can be lying and you know answer will be a lie. THAT IS THE ONLY WAY. It's boolean logical statement you learn these in comp-sci 101.
@@n00blamer It's not about the door, it's about the guy! If you ask him "If I were to ask you "Is this door safe?" would you say yes?" If he's a liar, he will lie about what answer he would give you! If he's a truth teller, he would tell the truth about which answer he would give you! If the door is death, either one would answer, "No, I would not tell you that this door is safe!" The Liar is lying when he says he would tell you No, but he still reveals the truth!
@@JonCox-hp4fw Death+Liar=NO (you survive), Death+Truth=NO (you survive), Safe+Liar=YES (you die), Safe+Truth=YES (you die) The problem with your logic is that if you're at death door you survive by your logic, but if you are at safe door you die by your logic. You cannot know which door is which, even if you short-circuit the answer. Now you need to know if the door is safe to know which answer to choose, but that's the puzzle: you DO NOT know which door is safe. or which guarding is a liar that's the problem we're solving here. The only solution that works is to know that the answer contains a lie. Your logic gives 50% probability to die, my logic gives 100% probability of survival.
"One of us always tells the truth, the other one always lies."
"Oh my god, Carl, I said I was sorry!"
If one of them says this whole line then he gives away that he's the one that always tells the truth, because the liar would have to lie about how it works. Similarly if the liar says one of us 'always' lies, then he just told you that he doesn't always lie. But if the liar says that one of us always tells the truth, then neither of them will always tell you the truth.
@calebwalters1869 the lier gave the setup.
Turns out both guards sometimes lie and both doors will kill you
Barbarian takes his ax and kills the first guard.
"Is he dead?"
*"......no."*
"This one liar."
Carl: “Oh, what a LIE! D’ooohohohoho!”
"barbarian takes axe and kills first guard" "is he dead?"
U came from that video too?
@@copycruel we are sheep fr
Now you don't know what door is safe.
"No"
"This one liar"
In this video the situation is stated that u can only ask 1 question
For those who didn't understand: Asking what door the other guard would tell me is safe, always leads to a false answer. If we ask the liar guard ¿What would the other guard say, if i asked wich door is safe? The liar guard would point to the damger door, since the other truthful guard would do the oposite. If we make the same question to the truthful guard, it would answer as the liar, and also point at the danger door. Thus, asking ¿What would the other guard say if we asked wich door is safe? always has the danger door as an answer. This way, we know wich is the danger door, and that the remaining door is the safe one :D I hope this explains it more concisely
It's guaranteed to point to the dangerous door, yeah. 😂 It's a good question.
you shold be the one who have made this video.
Thank you! This video did a horrible job of explaining this.
You include both the guards in the question since each have 50% chance of telling a lie, together they have 100%.
So you get the wrong answer of whatyou ask. If you ask for safety you are pointed towards danger.
If you ask for danger you are pointed towards safety.
Thank you. You explanation is comprehensible. The video, not so much.
"Do you have your helmet on your head right now?"
"No."
"Thank you to be such a good liar."
Fr, it’s so simple
@@NovaBoiii yea... so which door is safe?
@@davidjones-vx9ju
Ask them 🗿
You know which one lies and which one doesn’t
@@NovaBoiii you only get one question
@@NovaBoiii Just finding the liar doesn't mean you've found the door that leads to safety. It was never established that the liar automatically guards the danger door and vice versa.
Sometimes I need shit explained to me like I'm a newborn.
The words I've ever heard actually addressed to a newborn were, 'Breath, baby breath!'
She was my daughter and she breathed just fine, as soon as she felt like it. :)
don't ask a question, just go to one door, open it and push the guard through. If you hear screams of death then that was the danger door.
That was my thought.
Ahh, but what if you pushed the liar guard through the safe door, and he fakes the screams of death, thereby tricking you into going through the danger door?
@@wesscoates5676 Then just ask thru the door "Are you dead?" when the screaming stops.
@@davidtherwhanger6795 uuuuuhhh... huh... that might work.
The guard guards the door... your plan failed.
Just ask him what the other guy would say, this isn't a logical PUZZLE its a kindergarten riddle
This was very helpful. Usually I can never understand this riddle, but this helped me understand it.
'Takes barbarian axe kills one'
"Is he ded"?
"No"
"This one lie"
Unfortunately, you still don't know which door leads to safety and you wasted your one question.
I see a lot of people not getting the riddle. Part of this is because it's horribly explained in the video. First off, the guards can't speak except to answer one question (not one question each). So the instructions to the riddle have to be given by a third party, or a message on the wall or etc.
Second, this riddle involves two riddles in one, really. You have to determine which guard is lying, and which door is safe, and you only have one question. By asking either of the guards "which door would the other guard say is safe", you solve both riddles in one question. In either case, whether you ask the liar or the truthful guard, and no matter which door they guard, they will always pick the same door. So you can ask either guard the question and choose the opposite.
Finally, after all these years, that episode of Yu-Gi-Oh now makes perfect sense to me. Ever since watching that episode I thought it was madness but alas it was shear brilliance and you explained it so simply and elegantly. Well done ✅.
Which episode is it?
This puzzle becomes next level when there's only 1 door 1 guard and he lies half the time but you get 3 questions to figure out weather it's currently safe to walk through the door.
Does it like change to a dangerous one as soon as he lies?
He's playing this game on very hard mode 😅 I'll definitively give it a think ¿Do you have a solution? If you do, hats off 🎩
Anyone else get "Labyrinth" flashbacks? 😂
I'm amazed so few people got the reference.
Yep! The moment I saw the thumbnail, I thought of Labyrinth.
@@pyrrhicvictory6707 It's not a reference to Labyrinth. It's a very old puzzle. Labyrinth referenced this well known puzzle.
@@bassage13 Fair enough but I bet it was popularised by Labyrinth
if i ended up in that situation... i'll just go home and won't bother those guards :)
*You are literally in prison, stupid. Your only way HOME is through the door!*
Its really easy if you get the jist of it, alternatively you can kill them both but that would not be very nice to mr. honest.
The key factor that you omitted is that each guard knows that the other guard will respond in the opposite way. There are actually two ways of asking this question, you can ask about the door that leads to death which will reverse your response based on a yes or no answer. So there are two ways of asking this with 8 possible scenarios.
are you saying that the Liar would actually double-bluff?
@@RectanerTreadway no because they have to lie, if they double bluff or lie about lying they would be telling the truth by default and also second guessing the lie
@@josephrusso4748 yes true. I get what youre saying now. One can either ask re: the door to heaven, or you can ask re: the door to hell.
I doubt I’ll ever wrap my head around this conundrum. Thanks a lot Ricky, Steve, and Karl.
😂..feel the door to see if its hot
Look lads ive got some post for God here
@@domatron1578 😆😆😆😆😆
@@domatron1578 a moronic genius
You find a way to make them both say the same answer, IF they do so, then you know it's the opposite. The truth teller will accurately predict which door the liar will say is safe and that is always the danger door, and when that prediction matches you know that the liar was lying and that it's the opposite door.
Remember you're not asking them each which door is safe, you're asking them which door they think the other will say is safe. By doing so you know that the truth teller will out the liar by correctly predicting his lie.
You can also ask a hypothetical: "If I asked you if this was the door that leads to death, would you say yes?" If it is the door that leads to death, truthful will say yes, but liar will also say yes, because he is lying about the answer he would give you (a double negative) - "Yes, I would tell you yes (not true), this is the door that leads to death," getting him to lie about his lie has forced him to tell the truth. The same works in front of the safe door, where the same question will make both of them say no.
The classic problem has one unstated assumption, namely that the guards both know about the other being either truthful or a liar. If they didn't know each other, the truthful guard would truthfully answer "I don't know which door the other guard would tell you is safe" while the lying guard, it seems, could not give any logically coherent answer to the question.
Bro, Sarah taught me all I need to know here.
You dont ask the guards about what is behind them, you ask them about what is behind you.
But then you don’t know which door is the death door and life door
@@Cinnamon_Rolls_In_Pantry you must first determine which one lies, then you can ask about the door
@@RandomsFandom the whole point of the riddle is you can only ask them both one question.
@@RandomsFandom you only get one question each, idiot
@@Cinnamon_Rolls_In_Pantry Dude tried to be all 500 IQ Batman Professor X but just completely missed the point of the riddle lol
Basically the point of the riddle is to make a question that would result in the same answer from any of the guards. And at the same time this question gives us the answer to the riddle.
So the only way to do it is to "connect" the guards to each other by the question
I loved this conundrum when I was nine years old. I didn't do too well at school but then I did very well in my university entrance exams and went on to graduate from a top university with a GPA of 3,8....I did well at high school with lateral thinking problems ....I wish that I had had more confidence in my intelligence when I was at high school.
Ask the guards if theyre a guard who’s guarding a door, and go with the guard who says yes because obviously the guard who says no is lying.
Thought of my own question to ask:
Ask guard 1 if their door is safe: they say their door is safe.
Ask guard 2 if guard 1 just said that their door is safe.
If guard 2 says yes, you can tell guard 1 is lying because both can’t be telling the truth, and if guard 2 says no, you can tell guard 1 is telling the truth because guard 2 would be telling an obvious lie.
Walks up to one of the guards and sniffs ‘Did you poop your pants?’
There is confusion over the rules of the game on how many questions can be asked and how many guards get to hear the question(s). However, you can still find the safety door by asking only ONE guard ONE question: *"Would it be a lie if your told me this door leads to safety?"*
*(1)* If the "truthful guard" was standing in front of the *danger door,* he would say "Yes" because he cannot lie. ... You then opt for the other door.
*(2)* If the "truthful guard" was standing in front of the *safety door,* he would say "No" because he cannot lie. ... You then opt for that door.
*(3)* If the "lying guard" was standing in front of the *danger door,* he cannot say "Yes" because he can only lie. Based on your question, he would be telling you the truth because it would be a "lie" to tell you that the door leads to safety.
*(4)* If the "lying guard" was standing in front of the *safety door,* he cannot say "No" either because he can only lie. Based on your question, he would be telling you the truth because it would be a lie to tell you that the door does not lead to safety.
... Based on the wording of your *one question to one guard,* only the "truthful guard" can even offer you an answer! Based on the wording, the "lying guard" is forced to tell the truth either way - to which he is not capable of doing.
😪 i still cannot understand
By asking any guard what the other would say, you guarantee a lie. Either by asking the liar directly, or by having the honest guard tell you the what the liar would say.
Rules:
Guards are identical, although technically this does not matter for our logic, it helps to envision them this way to grasp the set of variables in this equation.
Only they know who is the Liar and who is Truth. Only they know who is guarding the passage to paradise.
It is not at all guaranteed that the Liar guards hell, nor that Truth-teller guards paradise.
You must also basically assume that the Liar intends to see you pick “the bad door” because in the roles of this puzzle, your own role is defined as you intending to pick the “good” door i.e. "Get out of the Dungeon". The conceit of the puzzle is that having a Liar involved at all presents the main conflict for us. We must neutralize this conflict somehow.
The goal is not to *fixate* on the liar and figure out who is who; the goal is to formulate a question that *reduces* the odds. A question that makes all the variables "non-randomized" but a better way to state this is, "to make all these variables incriminate the same culprit".
Game:
Scenario to prove the theory
Theory 1 - Honest guard in front of Hell. (To be known as Door U for Undesirable in our process of elimination. The door to paradise will be known as Door Y for YES.)
You can’t just ask the Honest-Guard if he’s guarding paradise because you must assume that he could very well be lying.
And you can't just ask him "what am I wearing?" or something redundant, because even if you prove that he's a liar, you still haven't proved that he is guarding the door that you need to select.
So, here we are, there's two inscrutable guards in front of two indiscernible doors, and I have no choice but to decide randomly who to ask a single question.
A. If I end up asking the HONEST guard “what would the other guy tell me to pick” he’d tell me *honestly* that the “other guy” would tell me *dishonestly* to choose his door aka Door U. -- This is logical because he's telling us that the Liar would want us to choose Door U (which both guards know as being Hell, and the Liar is interested in foiling our plans because I guess our enemies hired him to do that).
B. If I end up asking the LIAR (still unbeknownst to me his credibility) and ask same question "what would that other guy tell me to pick", he would default to his duty of lying, and tell me *dishonestly* that the other guard would "Pick His own door" aka Door U, again. Theoretically, this is dishonest because all we are allowed to assume via our theory is - that whoever the honest guard is, he would never advise us to pick Door U if we asked him directly. In other words, we need to assume if the honest guard is ever asked "what door should I pick" he will always tell us "the truth" aka technically "our truth" aka "the thing we want" aka Door Y.
While we cannot actually prove on-the-spot that the liar is lying, the phrasing of the question against the available facts allows us to eliminate 1 perilous door from our choices, no matter which guard we end up asking. Because the fact that the liar will exclusively provide misinformation is exactly what our clever question is taking advantage of: It's this process of elimination which means that "a second question" is not required. It is true however, that in the reality of this scenario, order to pick the right door, you MUST first ask the question. The question is required because it helps us receive more concrete data, and it's only with that new data can we THEN make our logical deduction. Therefore via the process of elimination which is now possible, you can determine that the other door, aka the only other door in front of you aka Door Y; is your remaining selection.
So to summarize; in both instances, Door U is alleged as the door to choose. No matter who I end up posting the question to, in both cases Door U will be alluded to, because in both cases the Liar will be responsible for tainting all the available data, giving you the opposite of what youre searching for. Knowing this, you also deduce that you must choose the opposite door from what is told to you "as conjecture", after asking that question which theoretically forces either of them to acknowledge an opposing factor, and thus both will indicate the exact same door.
@@RectanerTreadway what a deep explanation, thanks bro!
@@eskailerwhite.7593 i was stuck on this for a while myself so I understood your pain and wanted to alleviate the suffering if possible
Basically the answer is this: the guard that tells the truth would give you the answer of what the other guard would say which is the wrong answer since the other guard is a liar and the one you asked is the truthful one. In essence, he’s giving you the answer of what the other would say.
The guard that lies knows the other will tell the truth and since he lies he will give you the wrong answer as well because he’s a liar and that is not what the other guard would say.
In conclusion, the answer will always be the opposite of what the guard said, no matter which one you ask.
I can't! I really can't! People not understanding this even after the explanation just blows my mind away.
It literally took me 5mins to solve this. Seems like critical thinking, following simple rules and use of logic is not a thing anymore.
You can ONLY ASK 1 question to ONLY 1 of the guards.
So, you ask one of the guards (doesn't matter which one) something like: "If I were to ask the other guard which door is the correct one, what would he answer?"
If you ask the truth teller, he's gonna tell you the wrong door (because that's what the liar would answer).
If you ask the liar, he's also gonna tell you the wrong door (because that's the opposite of what the truth teller would answer).
By knowing this, you don't need to ask the question to both guards. You don't even need to know which one is which.
Since the outcome is the same in both scenarios, the other door will always be the correct one.
Side note: Asking for the wrong door, would also work, in that case you'd pick the same door as the guards. Literally the same, but reversed.
Simpler way to think about this is that the spoken answer contains what either guard would have answered on his own, in other words... the spoken answer IS ALWAYS A LIE because one of them is a liar, we simply guaranteed that the lie is always in the spoken answer.
"Am i sorry for killing his family"
"Ofc"
"Ok hes the liar"
Simple solution:
“Is the lying guard in front of the door to safety”
Honest guard in front of door to safety: No.
Honest guard in front of door to death: Yes.
Lying guard in front of door to safety: No.
Lying guard in front of door to death: Yes.
How do you know which guard is the lying guard tho?
@@lusterlessnova3199Check their comment again. It gives the same outcome for the corresponding door regardless of who is by it.
@@JustSomeKittenwithaGun I don't get it.
-Edit
Ohhhh. It's not about knowing who the lying or truthful guard is, but the answers they give. "No" leads to safety.
Appreciated~
The door to safety is always the guard who says “No”
Or the other door to the one who says “Yes”
@@lusterlessnova3199 I'll try to give my understanding of their comment so you'll hopefully understand it better. If either guard said no, you should go through his door regardless as the other comment described. If either said yes, go through the opposite door.
Why?
Remember, you only need to ask that one question to ONE guard only, but this still works if you're allowed to ask them both the same question.
“Is the lying guard in front of the door to safety?”
Guard says NO: If they're the liar, the actual truth is "YES".
The other guard MUST say no as well because otherwise there would be 2 lying guards. You can safely go through this door.
“Is the lying guard in front of the door to safety?”
Guard says YES: If they're the liar, the actual truth is "NO."
Again, the other guard MUST say yes or he'd be a liar as well. Go to the opposite door of the guard you asked.
Basically, you know which guard is lying because this question is really good and non-contradictory.
However, this is a contradictory question IF this condition is met:
If you asked them this specific question and one guard said yes, but the other guard said no it contradicts this question and this forces the truthful guard to lie.
Understanding this potential paradox is pretty helpful in understanding the solution.
If they both were to say no (or yes) at the same time to the question, then we know for a certain it isn't contradictory.
Well, I hope this didn't confuse you even more. I had to think pretty hard about it too.
"Are you a gaurd standing infron of a door" bam
“Are you a guard?”
How would this question lead you to know which door is the safe option? With this question you only know who is lying and who isn't, and as you only have one question, this doesn't answer which door is safe
@@tigrenaranjo”you can ask one of them only one question” is not violated by asking them to answer two different questions, one each. his solution asking the same question may be more elegant, but mine’s cleaner, and he didn’t state that limitation in the prompt as clearly as when he’s working through it. he arguably violated his own prompt if you’re going to be that pedantic, since he had to ask both guards a question anyway.
@@tigrenaranjoalternatively, you can also figure out the answer to this general riddle with one question if you’re listening carefully and given the prompt by one or both of the guards. the one who says they are guards or guarding a door is 95% the truth-teller unless they’re not actually guarding anything.
@@kazekagekid I think the implication is pretty clear you could only ask one question, to only one guard, to determine which door is safe, and the answer he gives in the video does not violate his rule; he simply demonstrates the answers each guard would give for each scenario to cover the possibilities, and that no matter which guard you ask or which door they are in front of - you only need to ask one of them and always choose the other door as the safe one.
@@kaptainkittens583 “you can ask one of them only one question” 0:37
Not to leave the room, even if you come and get him.
Me: *Tosses c4 onto both of the guards quickly then pulls out the detonator* "I'm going to push this detonator and blow you both to smitherines unless both of you point to the safe door." No need to ask a question.
Didn't Captain Jack Sparrow tell us that you shouldn't trust an honest man? 😂
Everyone seems to not realize they give themselves away without needing to ask a question. Let me explain.
The first one says "One of us speaks nothing but the truth." This is a true statement so whichever says this is the one who tells the truth.
Hence why the liar can only say the statement " The other nothing but lies." This one is calling the other a liar as to still abide by only telling lies. So he is the liar.
Simple and easy.
just ask the one who told the truth which door is safe.
Not really...
...The first one says "One of us speaks nothing but the truth." The liar could be saying this about himself, lying like always.
The other then says "The other, nothing but lies."
This then would still be a truth by the truth teller.
Definitely wrong. 😑
@@bugoobiga But that's not what they say. It's always one of us always tells the truth and one of us lies. The riddle is supposed to have a third party, or a note on the wall, or something like that, with the instructions, so the guards don't talk unless you ask a question. In this scenario, the OP is correct, the doors cannot give the proper answers. Both doors would have to state "We both always tell the truth".
Just ask the honest guard if he's guarding the safe door. If yes then walk through. If no then walk through the other door...
"what color is my hair" done
You only get one question
@infinitevoid227 *They would both answer the question tho? That's literally the entire point of the riddle!*
He's right I'm wrong, they answer the question and I now know who the liar is but have no idea which door is safe
@RitsuSakuma69 yes but even though you've found the liar you can no longer ask about the doors
The point isn’t to figure out which one lies it’s to figure out which door is safe
Ask one guard, "If I ask the other guard if this door leads to safety, what would he say?" Way I have it figured, if the guard says "yes" then the door leads to doom, and if the guard says "no" then the door leads to safety.
There’s the possibility they’re both a couple of psychopaths who are making it seem like your only way forward is one or the other door, when both actually lead to your demise and you were just supposed to continue down the hall to the exit.
"One can only tell the truth, the other can only lie."
All right, so tell me the color of my shirt.
*takes rock, throws it at one guard*
"Did I just throw a rock at you?"
One gripe ive always had with this puzzle is what if the liar guard just tells another lie?
For the question presented: "what door would the other guard tell me to go through?"
The liar guard could just say "he wouldnt answer." Which is a lie, and you dont get any information.
I like how Rick and Morty solved this 😂😂😂
Thats why i came here lol
Ask the truth answering guard which door is safe. DONE.
You ask 1 guard an absolute fact like: Am I a human?
Case 1:
Honest Guard : Yes
Now i know that this is the honest guard, then the other must tell a lie
Go to the other guard, and ask “Will I die if i go behind this door?”
Liar Guard will answer yes or no. Make your decision on the opposite of his answer.
Case 2:
Liar Guard: No
Now, i know that this is the liar guard.
Go to the other guard, ask Will if die if i go behind this door?
He will tell the truth so do as he says.
I followed the rule of asking only 1 question to both the guards each
_"You can ask _*_one_*_ of them only, _*_one_*_ question."_
You're dead because you didn't read the instructions.
The rule is one question only. Not one question each
Thanks you! The illustration really helped.
I thought you can only ask one question, period. Not one question to each guard, for a total of two questions.
Whoever explains the rules is the honest one. And will get you to safety.
The rules are not supposed to be given by the guards. A third party is supposed to tell you the rules, or they are displayed by a tablet, scroll, or message on the wall. The guards can only speak to answer one question.
And whatever you do, never say “It’s a piece of cake!”.
A mistake many riddlers make is when they state the puzzle, they have one of the guards as the speaker. This breaks the rules of the riddle unless the truth guard is the speaker... which also breaks the riddle.
I have 100 luck. I'll just toss a coin.
To the people who just want a logical truth like 1+1. You get no info about the door in that scenario you only find out who lies, but don’t get a second question to answer the door problem
Just ask a guard if they are alive. Liar says no, truthful one says yes.
Basicly you need to afk them a question they xan wriggle outfrom a question so obvious that the guard cant bank on symantics in your question
Easy solve "are you butterflies?"
The liar will answer that they are and the truth teller will say they are not.
So for the favorable outcome, do the opposite of "what the other guy would say?"
*ask the guard on the left and points to the right guard* is he alive?
If he says yes he only tells truth,
If he says No he only lies
If the guard is there to protect the door, why would he tell you to go thru it at all?
The Barbarian raises his axe and kills the first guard. He grabs the second guard and asks “Is he dead?” The guard says “No.” The Barbarian turns to the wizard and says “This one liar.”
Paused to answer... You ask either one of them the question "what would the other person say if i asked them what door they were guarding?" Whichever answer you hear is the answer to the door that the person you asked the question to is guarding.
Example, guard A always lies and is guarding the safe door. Guard B always tells the truth and is guarding the dangerous door.
You ask guard A "What door would guard B say he is guarding?" Guard B always tells the truth, and he is guarding the dangerous door. The truth is that guard B is guarding the dangerous door. Guard A has to lie, so he will say "Guard B would say that he is guarding the safe door." Guard A said "safe door."
Same question to guard B. Guard B always tells the truth, but he knows that guard A always lies. so when you ask guard B "what door would he say that he is guarding?" Guard A would say "he would say that he is guarding the unsafe door." Remember, guard A is guarding the safe door, but he always lies so he would say the dangerous door. Guard A knows that guard B always lies so would say "dangerous door". Guard B said "dangerous door" so we know he is guarding the dangerous door.
"is it true that one of you always tells the truth, the other one always lies?"
if he says "yes" do the opposite of the other guy if he says "no" do what the other guy says.
There are 3 guards, one always tells the truth, one speaks only lies, and the third one stabs people who ask tricky questions
Ask the following
1. If your door leads to hell, would you enter it?
2: You wouldn't. OK, so if it leads to heaven you go through first.
Youve made this needlessly complicated:
"Am i a human?"
Now that you know who's truthful ask the other "whats behind your door?"
Voila.
If there was one guard named Kairos Fateweaver, ask him any questions and he would will give you three answers, all of which are true, and horrifying to know."
Just ask how many doors are in the room
100% safe question: What is 1+1? Easy😂
my players would kill one and ask if the the other guard is dead then from there they can figure out what door to use.
1:06 (current point in the vid) assuming that the rules were explained by one of the guards then by default the guard that explained is the true one
the fact that you have to ask them what the other guardian would say makes too much sense if you think about it for a while... it's too easy, but not very well known yet.
yup; we know there is always a lie in the answer, the truthful dude won't affect it. the question has to include what both dudes would answer and there we go.
Ask first guard, “what is 1+1”
This determines which one is the liar.
Then ask the other guard which door is safe.
Since you know which guard is the liar, you know how to interpret his answer.
Bingo
But- you're only allowed to ask *one* guard *one* question. Your way is two questions which is not allowed. That's the rules of the riddle.
Just challenge the two guards to a card game labyrinth duel and then flip two coins and you’ll win.
The question was still asked twice..
But isn’t the only way they could admit that there’s one truth teller and one liar false? Because if the liar is saying “the one of us would speak only lies” that would be telling the truth. The only way they could both make that statement is if they were BOTH lying.
If you ask the wrong guard first you're screwed.
Nah if you asked "what would you say is the safe door if you were the other gaurd?"it doesn't matter who you asked because they would give you the same answer. Then you just choose the opposite of that answer.
@@aldobanuelos6614 reading that hurts.. I am still lost.
@@natas9967 Guard A always lies and stands before door X. Guard B tells the truth and stands before door Y. You don't know whether X or Y is the good door.
The riddle assumes that the truthful guard will point at the good door.
If you ask the liying guard what the other guard would choose, he would lie and point at the wrong door.
If you ask the truthful guard what the other guard would choose, he would tell you the truth and point at the wrong door.
Therefore, no matter which guard you ask, you always get your answer. You choose the other door since both guards will point at the 'bad' door.
Hope this helps :)
Ask both of them what color your shirt is.
Both the guards want you to think the other is true to kill you, if you ask "would he tell me to go through door 1" and they say yes its because they want you to think the other guard would send you to your doom
You can ask one of them only one question but your solution is to do the opposite of what they agree? How do you know what they agree if you can only talk to one? DOESN'T MAKE SENSE
I thought the puzzle allows only one question to only one guard. You're not supposed to be able to cross check the result against the other guard.
when you ask "what would the other dude answer" -kind of question you get both lie and truth in the spoken answer, the truth won't modify the lie it remains a lie so now you sneaked the lie to always be in the spoken answer. Since you know the spoken answer is always a lie you just take the other door.
*GRABS AXE WITH MACLLIOUS INTENT*
in the end you still asked two questions... am I wrong?
You are wrong. You ask one guard "what would the other guard say is the safe door?" and then you do the opposite of whatever answer you get. Just one question.
@@TheFilipFonky
Actually, OP is right. If you listen to the video at 3:00, the narrator clearly says “you have to do the opposite of what they agree on”. But in order to know what the guards agree on, you have to ask 2 questions. So this question is somewhat flawed.
@@tohian the narrator here is implying that they would *theoretically* agree on the same door if asked the same singular question. in other words, you only need the 1 question to prompt them both into giving you the same response meaning no matter who you ask, you can safely assume what the other will say
@@tohian it's not. They would always agree on the same door.
They would both answer at the same time but you still get the right answer, so it's one question.
No need to over complicate it. Ask which leads to safety. Simply ask which one leads to certain death. You don't ask which door is safe. If you ask the liar does this lead to certain death he will say no. And it it is the Truthful gaurd he will say yes.
this is making the assumption that each guard knows that one lies
Hint hint the one who explains how the riddle works is the truthteller.
How many fingers am I holding up if one says the right number than its the truth but if the other says the wrong number then he lies
But what if the truth teller is guarding the death door?
That’s the catch, you only get the one question. After you figure out who the liar is, you are out of questions and will never know which door is safe.
Well can’t you ask the other one the question
@@TheJM5 nope only one question for one guard. It’d be too easy otherwise
@@infinitevoid227 that’s stupid then how do I know who’s lying
I’d just tell them “my name is (name). Is my name (name)?”
The one who answers yes is the truthful one
you know which guard is liar, cool. you had only one question. 😥
Third option. Go through a door at a 50/50 option
Chuck Norris would hit them with so many rights, they would beg for a left. And then tell him which was the safe door. Lol.
Are we in a dungeon=instant success
You still don’t know which door is safe
@@TinyFord1 oh wait why did i not think of that bro😭😭😭
I know how to solve it. You hit one you tell the other did I hit him?
Ask one guard what's 2+2
If he answers 4 then the other guard which door is the dangerous
one and go through that
If the guard respond incorrectly then ask the other guard about the safe door and go through that
But which guard is telling the truth,if you don't know which one lies and which one is honest???
Ask one of the doors.. "so I can ask two questions right?" ... The truthful door would say no.
But then you still wouldn’t know if the the door led to safety
@@sundew3848 both doors have the same outcome.
Youre not trying to find a lying door. Youre trying to find which door leads to safety by asking a guard
Easy puzzle just ask if i was to ask the other guy what door to go though what would he say. then u just do the opposite of whatever they say since both guards would agree on the wrong answer.
I thought you could only ask one question between the two of them, not one question for each guard?
It's just showing what would happen per scenario. If you asked the liar if his door was safe, (and it waa dangerous) he would say yes. The same would happen to the truthful one.
“Does 2+2=4?”
“Uhh…Nope.”
You will learn who is the liar, but not which door is safe. The trick with this question is you only get one, and need to determine which door is safe with that limitation. This video is poorly structured, so its easy to misunderstand like I did initially.
@@emergentc5398ask the one who lies which one is safe and pick the opposite of his answer
Just ask one guard a simple math question like 1+1. If he gets it wrong, he is the liar
If they tell you that you can only ask one question, you can solve it in one move by asking one of them "What will the other guard tell me is behind his door if I ask him?" If you are asking the truthful one, it will be the opposite of whatever he reports because the truthful one takes into account that the liar will indeed lie. If you are asking the liar, it will be the opposite of whatever he reports because the liar will give you an inaccurate account of what the truthful one will say. So, if the answer is (bad thing), go through the other guard's door. If the answer is (good thing), go through the door behind the guard you are asking.
Pick a door, and ask them: Will you say this door is safe?
1. The door I picked is safe:
1a. The honest guard: Yes
1b. The lying guard: (I would lie and say that door is not safe, but then I also have to lie about the fact I would lie and say that door is not safe) Yes...
2. The door I picked is dangerous:
2a. The honest guard: No
2b. The lying guard: (I would lie and say that door is safe, but then I also have to lie about the fact I would lie and say that door is safe) No...
I read a riddle about this sort of thing many years ago, and the answer is much easier than you make it sound! You just go up to one of the guards and ask "If I were to ask you if this door lead to safety, would you say yes?"
The trick is to have both guards answer the question, this is done by asking either guard what the other would answer.. now you would know that the answer always has a lie in it. If you ask: "which door would the other dude say is the safe one?" or "would the other dude say THIS door is safe?" .. whatever the answer is, you know it's going to be a lie.. so you take the other door and go watch netflix and chill.
@@n00blamer Think about it! If I ask the liar who is standing in front of the death door, "If I were to ask you if this door leads to safety, would you say yes?" His response is always a lie! If I ask him if he would SAY yes, He would lie about the response he gives, so he would say "NO!" thereby revealing the truth about the safety of the door!
@@JonCox-hp4fw .. and if you stand in front of truth door with life behind it, he would say YES.. so how you know which door you stand in front of?
You need to be certain that the answer has a lie so that it can be cancelled out, only way is to format the question in a way that both doors contribute. "what would the other guard say about this door", then either can be lying and you know answer will be a lie.
THAT IS THE ONLY WAY. It's boolean logical statement you learn these in comp-sci 101.
@@n00blamer It's not about the door, it's about the guy! If you ask him "If I were to ask you "Is this door safe?" would you say yes?" If he's a liar, he will lie about what answer he would give you! If he's a truth teller, he would tell the truth about which answer he would give you! If the door is death, either one would answer, "No, I would not tell you that this door is safe!" The Liar is lying when he says he would tell you No, but he still reveals the truth!
@@JonCox-hp4fw
Death+Liar=NO (you survive),
Death+Truth=NO (you survive),
Safe+Liar=YES (you die),
Safe+Truth=YES (you die)
The problem with your logic is that if you're at death door you survive by your logic, but if you are at safe door you die by your logic. You cannot know which door is which, even if you short-circuit the answer. Now you need to know if the door is safe to know which answer to choose, but that's the puzzle: you DO NOT know which door is safe. or which guarding is a liar that's the problem we're solving here. The only solution that works is to know that the answer contains a lie.
Your logic gives 50% probability to die, my logic gives 100% probability of survival.
“One is lying, and the other is lying to himself.” -a dude from another video probably in 2022 or 2023