Brainteaser: The Truthteller and the Togglers

[ProfessorFarnsworth]

Yes he can say everyone but himself and it still be a complete lie. The question is who are the four togglers, not who among you are togglers.

That makes me think of another one. The first quesion is, who among you are togglers. The truth teller will name everyone but himself, a truth telling toggler will have to include himself, and a lying toggler will only be able to name the truth teller. Either way, no second quesion is needed.

That's true.

Hence why I mentioned the idea of making them point to all four of them, because it prevents the whole "everyone but themselves" style vague answers and forces them to name names.

But I suppose like you said asking, "Who specifically are the four togglers among you?" would circumvent vague deceptive answers like that.

But it's important to specify the number of togglers too as leaving anything to open interpretation in your question, allows them to be more deceptive in answering.

[Osensitive1]

But here's the thing, a lying toggler actually cannot say everyone but himself, because it's an half-truth

Yes he can say everyone but himself and it still be a complete lie. The question is who are the four togglers, not who among you are togglers.

That makes me think of another one. The first quesion is, who among you are togglers. The truth teller will name everyone but himself, a truth telling toggler will have to include himself, and a lying toggler will only be able to name the truth teller. Either way, no second quesion is needed.

That's assuming you get the correct person on the first attempt. As I said, the truthteller can't actually be revealed until Q2 has been answered, as no-one will know for sure who is who (except those being asked) and the questioner has to do the finding out.

No. My logic is sound. It doesn't matter who's asked. No second question is needed.

[Osensitive1]

Yes he can say everyone but himself and it still be a complete lie. The question is who are the four togglers, not who among you are togglers.

That makes me think of another one. The first quesion is, who among you are togglers. The truth teller will name everyone but himself, a truth telling toggler will have to include himself, and a lying toggler will only be able to name the truth teller. Either way, no second quesion is needed.

That's true.

Hence why I mentioned the idea of making them point to all four of them, because it prevents the whole "everyone but themselves" style vague answers and forces them to name names.

But I suppose like you said asking, "Who specifically are the four togglers among you?" would circumvent vague deceptive answers like that.

But it's important to specify the number of togglers too as leaving anything to open interpretation in your question, allows them to be more deceptive in answering.

Good point on the deceptive truthful answer of not naming them all; naming only two or three. Though now convinced this shouldn't need two questions and will think on better wording which neither includes specific numbers nor leaves room for trick answers. Who are the togglers is key.

[P7PSP]

Question 1 could be: Are you a liar?

The truthteller will always answer 'no' to this, as they never lie. The togglers will answer either yes or no, depending if they are lying/telling the truth. Either answer could still provoke a second question, as you can't confirm the liars/truthtellers from just the one question.

The second question therefore is a tricky one, and as you still have all 5 participants in play, it means it has to be a question that will nail the case shut. Unfortunately, I haven't the foggiest of what to ask for that one.

Well, if you or anyone else can come up with another correct answer, it'd be good to post. Who knows how many correct answers this problem has.

Kill them all, God will know his own. 

[Calavera]

Question 1 could be: Are you a liar?

The truthteller will always answer 'no' to this, as they never lie. The togglers will answer either yes or no, depending if they are lying/telling the truth. Either answer could still provoke a second question, as you can't confirm the liars/truthtellers from just the one question.

The second question therefore is a tricky one, and as you still have all 5 participants in play, it means it has to be a question that will nail the case shut. Unfortunately, I haven't the foggiest of what to ask for that one.

Well, if you or anyone else can come up with another correct answer, it'd be good to post. Who knows how many correct answers this problem has.

Kill them all, God will know his own. 

Stuff what we want to know, eh?

[Osensitive1]

What do you think of the professor's point, Mcalavara?

[Calavera]

It's not my brainteaser, so I can't really know whether a half-truth is considered a lie.

But, personally, I prefer the answer you gave, which avoids such conundrum and still ends up being correct.

My approach is: the simpler, the better.

[Osensitive1]

Maybe just who are the togglers is a better choice of words than who among you are togglers.

[The_Chosen_One]

But that question is never going to reveal the truthteller, unless you already know the answer.

And as the questioner, you are supposed to work out who is who without any background information.

Asking 'who are the togglers?' is only going to get one truthful response at first. The second question is needed for clarification.

Maybe a better question would be "Are any of you Jesus Christ?" You would know neither of them aren't, but you still don't know the truthful response.

Anyway, I think the definite correct answer to this is needed.

[Osensitive1]

I gave a definite correct answer. You're not reading what I wrote.

Q:Who are the togglers?

The truth teller can only answer, everyone but himself. This identifies him as the truth teller.
The truth telling toggler must include himself in the answer. This identifies the truth teller.
They lying toggler can only name the truth teller as a toggler. This identifies the truth teller.

Only one question is needed.

[ProfessorFarnsworth]

It's not my brainteaser, so I can't really know whether a half-truth is considered a lie.

But, personally, I prefer the answer you gave, which avoids such conundrum and still ends up being correct.

My approach is: the simpler, the better.

My approach is to cover all bases by ruthlessly analyzing and construct as flawless solutions as possible, with contingencies in mind as insurance against failure. My paranoia disorder tends to make me think like that. 

[The_Chosen_One]

I gave a definite correct answer. You're not reading what I wrote.

Q:Who are the togglers?

The truth teller can only answer, everyone but himself. This identifies him as the truth teller.
The truth telling toggler must include himself in the answer. This identifies the truth teller.
They lying toggler can only name the truth teller as a toggler. This identifies the truth teller.

Only one question is needed.

But there are no truthtelling togglers. They run on a pattern of lie/truth/lie, or vice-versa. So if their first answer is a lie, there is only one truth, and that comes from the truthteller. AAll the rest thus have to be winnowed out with a second question.

Say I asked you, are you a toggler? Your answer would be no, but the others are. If you are the truthteller, that still doesn't give me the information I need, because you could be a toggler lying. If you are a toggler lying, then you are hardly going to say the truthteller is the truthteller because you will admit you are lying. So a toggler will never say yes to that question, because they will be causght out. Problem ther is that if you only have one shot at asking the question, then finding the truthteller first go is like looking for a needle in a haystack. You have to assume they are all telling the truth, and then ask for clarification. Can't be done any other way, I'm afraid.

[Osensitive1]

Yeah. Thinking you're trolling me again. It's in plain black and white. Toggler, whether telling the truth, or telling a lie, identifies the truth teller. It's simple. The question isn't are you a toggler, but who is a toggler/ who are the togglers.

[The_Chosen_One]

Yeah. Thinking you're trolling me again. It's in plain black and white. Toggler, whether telling the truth, or telling a lie, identifies the truth teller. It's simple. The question isn't are you a toggler, but who is a toggler/ who are the togglers.

No, you said the question is 'are you a toggler?'

Even the question 'who is/are the toggler(s)?' won't give you the answer you want on the fiirst question.

Why do you accuse trolling when someone disagrees with you?

[Calavera]

Yeah. Thinking you're trolling me again. It's in plain black and white. Toggler, whether telling the truth, or telling a lie, identifies the truth teller. It's simple. The question isn't are you a toggler, but who is a toggler/ who are the togglers.

Even the question 'who is/are the toggler(s)?' won't give you the answer you want on the fiirst question.

It depends on how a lying toggler answers. If he's going to be completely lying, then yes, one question only is needed. If he's going to mention himself as a toggler along with the Truthteller, then yes it becomes a problem.

Both of you are right.