# Which Door Leads to Heaven?



## jdsouza (Jul 29, 2012)

There are two doors and seated before each, is one spirit being.  

One is the devil, who is a compulsive liar.  The other is an angel, who always tells the truth, regardless.  Both converse with only a "Yes" or a "No".

There is no way to tell which of the two is the devil / angel.

One of the doors leads to heaven, the other to hell.  And you need to know which door leads to heaven.

You are allowed to ask any ONE of the spirit beings only ONE question.

What would your question be and based on the response know which door leads to heaven?


----------



## madforgolf (Jul 29, 2012)

Ask which door leads to heaven.
 The devil will point to hell, the angel will think of the answer that the devil will say and also point to hell leaving you to take the other door.


----------



## jdsouza (Jul 29, 2012)

Ask the question for which you expect only a Yes or No as an answer.

You're so 'somewhat' right.  Perhaps, memory needs to be jogged a bit more ..


----------



## shg (Jul 29, 2012)

"If I were to ask you if the door on the right leads to heaven, would you say yes?"


----------



## jdsouza (Jul 29, 2012)

Nearly there.


----------



## shg (Jul 29, 2012)

If it were true, the angel would say yes, and the devil would say yes (if asked if it were the door, he'd say no; asked if he were asked, he'd say yes).


----------



## jdsouza (Jul 29, 2012)

Your question could have stopped at "Is this the door that leads to heaven?"  Then the opposite of the Yes or No answer would be unambiguous.


----------



## shg (Jul 29, 2012)

What am I missing? The angel and devil would always give opposite answers to, "Is this the door that leads to heaven?"


----------



## jdsouza (Jul 29, 2012)

Door ADoor BDoor ADoor bDevilAngelAngelDevilWhat would the being in front of Door 'B' say if I asked him, is Door 'A' the door that leads to heaven?What would the being in front of Door 'A' say if I asked him, is Door 'A' the door that leads to heaven?What would the being in front of Door 'B' say if I asked him, is Door 'A' the door that leads to heaven?What would the being in front of Door 'A' say if I asked him, is Door 'A' the door that leads to heaven?

<tbody>

</tbody>
The correct answer is ..

The angel and the devil would give the same answer  but the opposite is true.
What would the other entity (spirit being) say if I asked him, it this is the door that leads to heaven?

If the answer obtained is "Yes", Actually Door 'B' leads to heaven.  If the answer is 'No' then Door 'A' leads to heaven.


----------



## shg (Jul 29, 2012)

I think mine is equally valid.


----------



## jdsouza (Jul 29, 2012)

HeavenHellDoor ADoor BAngelDevilYour Question - "If I were to ask you if the door on the right leads to heaven, would you say yes?"Your Question - "If I were to ask you if the door on the right leads to heaven, would you say yes?"Answer would be "Yes" and you say the opposite is true !The answer would be "Yes" as the Devil always lies and you say the opposite is true !

<tbody>

</tbody>

Perhaps, you'd like to reconsider your question to the spirit beings?


----------



## Oaktree (Jul 31, 2012)

Not only is shg's answer valid, it's technically more correct.  "What would the other entity (spirit being) say if I asked him, it this is the door that leads to heaven?" assumes that the two entities have knowledge of each other's habits, which is not necessarily guaranteed by the construct of the problem.

Two truths = correct classification of the door.  Two (offsetting) lies = also correct classification of the door.  

Plus, with shg's answer, you could remove one of the statues entirely and, armed only with the knowledge that the statue either *always* lies or *always* tells the truth, you could pick the right door.


----------



## jdsouza (Jul 31, 2012)

Entirely entitled to your opinion.

The assumption that both entities (not just those attempting to solve the problem) know about the entity's habits is correct.

Put in the other combinations in the matrix in #11, ask the same question, see if it is conclusive that the opposite is always true.  If so, I'm missing something.


----------



## Oaktree (Jul 31, 2012)

Per #11, think of shg's question in two parts:

We all agree that the demon knows door B leads to hell, but if asked if it leads to heaven, would lie and say "yes"... but, that's not shg's proposed question.  

By asking "If I were to ask you... would you say yes" you're missing that this implicitly introduces a second round of questioning.  You're not asking whether the door leads to heaven, you're asking the entity to tell you what his *reply* would be.  Shg's question would force the demon to lie about the *reply*, thus stating a truthful "no", that the door would indeed lead to hell (or, conversely, a truthful "yes" if it was the door to heaven).


----------



## jdsouza (Jul 31, 2012)

If only the proposer knew which of the two was the devil.

If the being happened to be the angel ..
"If I were to ask you that this door leads to heaven... would you say yes"
The being's answer would be 'Yes' (if led to heaven).  Then, the opposite can't be true.  Or can it?


----------



## Oaktree (Jul 31, 2012)

You don't need to know which one's the devil.  With the "If I were to ask..." construct, you'll get a truthful reply whether you ask the demon or the angel.

Door A (Heaven Door)
Without the "If I were to ask..." construct, Angel would say it's heaven.  Would also *say* he'd say it was heaven (this is where the "If I were to ask you" construct comes in to play), so you know it's heaven
Without the construct, Devil would say it's hell.  With the construct, he would *say* he'd say it was heaven, so you know it's heaven.

Door B (Hell Door)
Without the construct, Angel would say it's hell.  With the construct, he would also *say* he'd say it was hell, so you know it's hell 
Without the construct, Devil would say it's heaven.  With the construct, he would *say* he'd say it was hell, so you know it's hell


----------



## BenMiller (Jul 31, 2012)

Simply put, shg makes it a double negative - or a double positive - which means that you will always get the correct answer.

This assumes that the devil lies for the sake of lying, and not for the greater sake of evil; or he's really stupid. Because if he gets such a ridiculous question from you, surely he'd think to himself for a bit and see what you're up to. So either he's stupid and doesn't realize your intentions, or he is more devoted to lying than to being evil (and making you end up in hell). In which case he is not the devil, and is merely a lying machine incapable of judgement.


----------



## jdsouza (Aug 1, 2012)

I had responded, but it seems to have disappeared.

Will wait a bit and re-post.


----------



## jdsouza (Aug 1, 2012)

HeavenHellHeavenHellDoor ADoor BDoor ADoor BAngelDevilDevilAngelIf I were to ask you if the this door leads to heaven, would you say yes?If I were to ask you if the this door leads to heaven, would you say yes?If I were to ask you if the this door leads to heaven, would you say yes?If I were to ask you if the this door leads to heaven, would you say yes?YesNoYesNo

<tbody>

</tbody>


HellHeavenHellHeavenDoor ADoor BDoor ADoor BAngelDevilDevilAngelIf I were to ask you if the this door leads to heaven, would you say yes?If I were to ask you if the this door leads to heaven, would you say yes?If I were to ask you if the this door leads to heaven, would you say yes?If I were to ask you if the this door leads to heaven, would you say yes?NoYesNoYes

<tbody>

</tbody>

The above shows that "the opposite" is not true.

When the 'would you say yes' in the question above is used as a quoted response - 'would you say, "Yes"?, then the answer indicates if the door leads to heaven if the answer is "yes".

If the 'would you say yes' is used in the context of 'would you agree?' it becomes inconclusive.  

Therefore, not a shorter or better solution.  Therefore my comment - 'nearly there'.


----------



## BenMiller (Aug 1, 2012)

jdsouza said:


> If the 'would you say yes' is used in the context of 'would you agree?' it becomes inconclusive.



I've never heard "would you say yes" used in that context. Then again, I don't hang out with angels and devils too often.


----------



## jdsouza (Aug 1, 2012)

In the other context, it would have to be
... would you say, "Yes"?

If the construct is not like that - it does not mean the other context.  If I remember, correctly?

Was fun all the same ...


----------



## BenMiller (Aug 1, 2012)

I do not think so.

The sentence: Would you say that France is better than Germany at skiing? Does not mean that you're actually saying the words, "that France is better than Germany at skiing".

_Say_ is not always taken literally. See the third definition here.

_Yes _as a verb is a word used to express affirmation. _Yes_ as a noun is the affirmative reply.

So "Would you say yes?" means "Would you opine in affirmatively?"​


----------



## jdsouza (Aug 1, 2012)

Exactly what I wrote.

However, if you want to hear or read the word, "Yes".  You would have to write it accordingly or else it will mean "would you opine in affirmatively?"  or as I put it "would you agree?"

The logic to make the contrary solution viable, mandates : would you say, "yes"?


----------



## Atroxell (Aug 1, 2012)

Perhaps the true lesson here is to live life in such a way that you don't have to ask which door it is...

(Sorry, I could not resist.  And now, back to a more meaningful discussion on the topic...)


----------



## PAUL_DOMEIER (Aug 10, 2012)

I believe I have seen this before and sorry if you guys have already came to an agreement but I'm going to through my $.02 out there anyway haha

I believe that the correct question is this 

Approaching either of them (if you don’t know what one is which) and ask would the other one tell you to walk through door A or B (you would choose which every door you please) if he/she says yes or no which ever answer he/she gives you, you would do the opposite of that and be saved!

Example you approach the Liar and ask would he/she (the truth teller) tell me to go through door A or B (just pick one) the lair would tell you that the other would tell you to go to the door that brings you to hell. If you did the opposite of that you would be saved!

Example 2 you approach the truth teller and ask would he/she (pointing the lair) tell me to go through door A or B (pick one) the true teller knowing the intent of the lair would tell you the door that brings you to hell. Pick the opposite and you’re saved


----------

