In the country Logicala, everyone is either a politician or a mathematician. Mathematicians always tell the truth and politicians always tell lies.
One day, three people from Logicala meet: Joe, Jane, and Jim.
How many of the three people are mathematicians?
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We don't have to assume they know each other. From their statements it is obvious that Jim knows what profession Joe has. Otherwise he would remain silent. If he is a mathematician, he cannot lie, if he is a politician he cannot speak the truth. So both mathematicians and politicians must remain silent on topics where they are not sure.
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Yes, you've made that important point, which is that Jim knows what professional Joe has, otherwise he'd have to remain silent.
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Yes, and nobody else need know the profession of anybody else.
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@Richard Desper – Okay, fixed my solution, have made an edit at the start.
If only politicians would remain silent on topics about which they know nothing....
If Joe were a Politician, his claim would be false, and the opposite, "I am not a mathematician or a politician" would be true. But this is not possible because then Joe would not be Logicala, since all of Logicala must be Political or Mathematical. Therefore, Joe is a mathematician.
On the other hand, Jane is Politician (she lies): Joe has not said that he is a mathematician, but he has said that he can be a mathematician or not.
Finally, if Jim were a mathematician, Joe should be a politician. On the contrary, if Jim a politician, the opposite of what he says would be true, that is, Joe is not a politician, and therefore he is a mathematician, as we have already deduced above.
The correct answer is 1 mathematician (Joe)
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Accepting that Joe's two statements have not been said by him at the same time and in the same sentence, implies that either he has said one, or he has said the other. This puts us in another scenario.
2.- Joe is a Mathematician. This implies that he says the truth and therefore is a Politician. We are in the same situation as point 1.
Therefore, either Joe is not from Logicala, or he can not have said that he is Politician. He has definitely said he is a Mathematician. And therefore he has told the truth: it is Mathematician.
Jane is evidently telling the truth by stating that Joe has said that he is Mathematician. Therefore, he is also Mathematician.
If Jane had said otherwise, "Joes is Politician," she would be lying. This is what Jim knows. So Jim is lying: he is Politician.
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Clarification:
Joe can be Politician, but then he can not say that he is Politician because it would imply that he is telling the truth (contradiction).
Joe can be a Mathematician, but then he can not say he is Politician, because he would be lying (contradiction).
Therefore, Joe can not have said in any case that he is Politician. He has said that he is a Mathematician, and therefore he is a Mathematician.
I misinterpreted the statement, understanding that Joe said to Jane:
"I am a politician or I am a mathematician.",
instead of the right thing:
"I am a politician" or "I am a mathematician."
I guess saying that “Jim must know whether Joe is a politician or not” depends on your definition of lying. Does saying a non-truth whether you know it is a non-truth or not constitute lying? If so, it doesn’t matter whether Joe knows what Jim is.
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In the world of Logicala, even if you are a liar, you must absolutely tell a lie whether you want to or not. So, for example, say I am a liar in Logicala, and you offered me a $20 bill, asking, "first you must answer, will you take this $20?", I must say.. uh... ? A real politician will snatch it, saying, "yes, thank you".
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Lie - to speak an untruth, intent is an issue at law, not in the truth or falsity of logic statement
If Joe said I am a politician, then this contradicts the fact that in Logicala everyone is either politician or mathematician.
So Joe must have said that he is Mathematician.
Since in logicala everyone is either a politician or mathematician therefore Joe is telling the truth , that is Joe is a mathematician and this is also told by Jane. That is why for telling the truth Jane is also a mathematician. And from this it is clear that Jim is a politician as he is not telling the truth. Therefore there are two mathematicians.
@Michael Mendrin it bugged for a while, but no, it doesn’t change the truth value of a person’s statement if they know or don’t know it to be true. So, we don’t have to assume that Jim knows whether or not Joe is a politician.
It does not change the logic of the rest of your answer.
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Well, if Jim wouldn't know whether Joe lies or not, he wouldn't himself know whether he's lying or not, and that can't be the case.It doesn't change the only possible outcome, but it would introduce the weird situation, that Jim wouldn't know what he is himself, and then taking the outline very strictly, he couldn't speak.
EVERYone in Logicala must say “I am a mathematician”
That’s the only thing Joe could have said, so we KNOW Jane is saying the truth and hence a mathematician
Then the only two possibilities are that one of Joe or Jim must be lying, hence two mathematicians.
I used SJW method. Joe is a white male, therefore must be a bad lying politician. Jane is a girl, and Jim is a black guy so they both are honest. Easy. (Please take it as a joke:)
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Mathematicians are trained to think of all possibilities, so consider that Joe could be gay and therefore honest.
That kind of thing is never a joke. At best it's very rude.
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Wrong, it IS frequently a joke, especially as social justice warriors are a joke.
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@Dennis Rodman – Have you asked a SJW on that matter?
1) The picture in the problem is wrong. It shows Jane facing Joe as she is stating what she says, but she states her content to Jim. 2) This is "Intermediate" level stuff, not "Basic."
If Joe were a mathematician, he would have truthfully said "I am a mathematician" . If he were a politician he would have falsely said "I am a mathematician" . Therefore we know that Jane is telling the truth (Mathematician) as Joe will definitely have said this.
Jim then goes against Jane by telling her she is wrong, meaning that Jim must be lying (Politician) .
Since Jim is lying and he says Joe is a politician, Joe is a mathematician .
Hence there are 2 mathematicians.
I don't think this is quite right. Jim's statement does not claim Jane is wrong in any sensible way. Jim is saying that something is wrong because Joe is a politician. What is wrong? It must be that Jim means that Joe's claim is wrong because Joe is actually a politician. Jim is either telling the truth about Joe's claim or lying about Joe's claim.
The "wrong" that Jim is stating cannot be Jane's full statement. "That is wrong, Jane! Joe could not have claimed to be a mathematician because he is actually a politician" is not logically correct, because both kinds of people would deny being politicians. The universe (named "Logicala") assumes that all the people are logical. Thus, Jim is not telling Jane that she is wrong, he is telling Jane that Joe must be wrong. Either Jim is telling the truth and he and Jane are mathematicians, or Jim is lying and actually Joe and Jane are mathematicians. Either way, 2 of them are mathematicians.
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This is using a very weird definition of "logical" when you say "all the people are logical" (which is your main reason you think "That" isn't referring to Jane's statement). Lying is, by its own nature, inconsistent with reality, hence illogical, so by your argument nobody could be a politician, because it's not a very "logical" choice.
In the end, all this is semantic nonsense. The unarguable fact of the matter is that the word "That" in Jim's statement is ambiguous. Luckily, no matter the reference for "that", we have two mathematicians, so the answer itself is still consistent.
Jim is not telling Jane she is lying. Jim is saying that Joe's claim is a lie.
I used an uncommon, random method. First I figured out it is impossible to say you are a politician. If you are a mathematician, you would truthfully say “I am a mathematician”. If you are a politician, you would untruthfully say “I am a politician”. That means Joe said “I am a mathematician. Because we know that, we know John is telling the truth, which means he is a mathematician. We do not know if Joe is telling the truth or not, but we know if Joe is a mathematician, then Jim is a politician and vice versa. This is because if Jim is lying, then the question states Joe is telling the truth, and vice versa.
Hopefully this helps, even though it is confusing.
Then you confused. ” Jim replies, “Joe is not a politician, but a mathematician. Means that Jim states the same. You should formulate ” Jim replies, “Joe is not a mathematician, but politician
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Thank you a lot for explaining this better than me
A politician would say they were a mathematician too.
Helps enormously. Sweet clear thinking. Thx. Peter.
Who is John?
I don't recall being involved in this problem. Did you mean Jane instead of John?
A politician cannot say "I am a politician", this is a typical Zeno's paradox. Therefore Joe must be a mathematician. Then everything becomes obvious.
That's what I did!!!!!!!!
In Logicala, it is impossible to say "I am a politician" since that carries the same logical fallacy as "This sentence is false." Therefore Joe must have said "I am a mathematician". Jane must be a mathematician from her statement. Lastly, since Joe and Jim are saying contradictory statements, they cannot be the same type of person. Thus, Jane and either Joe or Jim are mathematicians, making 2 total mathematicians.
It's impossible for Joe to say that he is politician since that'll form a paradox, if he was telling the truth he wouldn't be a politician since politicians always lie, and if he was a politician he couldn't say it because that would be the truth. Now we know that the only possible statement from Joe is that he is a mathematician, regardless whether he is politician and lies or mathematician and tells the truth. By this we know that Jane's statement is true, since he did claim he is a mathematician, bringing us to 2 scenarios: Jim is the politician, since he lied that Joes is not a mathematician or Joe is a politician and lied that he is a mathematician and Jim is mathematician, either way, there are 2 mathematicians.
You know what they say, right? There has never been a more wretched inferno of lies and villainy than congress. Oh well, if more people were mathematicians, maybe the world would be a better place.
In this situation, three people from Logicala discuss whether or not our charismatic buddy Joe is a mathematician. So, how many politicians, and how many mathematicians, are present in this discussion?
First of all, notice that Joe always claims to be a mathematician. If he's a mathematician, then his job is to deliver the truth, and if he's a politician, his mouth is a cesspool of lies. Therefore, our friend Jane is a mathematician for sure, as she's telling us exactly what she hears from Joe.
How about our elegant friend Jim, with his black tie and suitcase? If Joe is a mathematician, then Jim is a politician, and vice-versa. See, only a mathematician would be brave enough to dispute the irrational claims of politicians, and only a politician would dare question the impartial truth of mathematics.
In either case, there are definitely two mathematicians in this scenario. Jane is definitely a mathematician, and Joe is a mathematician if and only if Jim is not .
You know, just to be safe, I'm going to take Logicala off my vacation plans. I think I'd prefer Costa Rica or something... any suggestions?
Joe says "either a politician or a mathematician " ,hence he is never wrong. Now ,either one from Jane and Jim must be wrong... Hence,2 truths and a lie. So 2 mathematician and a politician.
Joe without a doubt does not say he is a politician because if he really is a politician, he would tell a lie that he is a mathematician; and if he is a mathematician, he would tell the truth which is his true identity, a mathematician. In either case, Joe is certainly saying he is a mathematician.
If Joe says he is a mathematician and Jane says that Joe claims to be a mathematician, then she is telling the truth. Jane must be a mathematician.
Now let's connect Jim's statement with Joe's true identity. In case 1, if Joe is a politician, then Jim is telling the truth and is a mathematician. In case 2, if Joe is a mathematician, then Jim is telling a lie and is certainly a politician. In either case, there is one person who is a politician and the other is a mathematician.
In the end, Jane is certainly a mathematician and either Joe or Jim is a politician and the other is a mathematician and this concludes that there are 2 mathematicians and 1 politician.
Regardless of his profession, Joe will say that he is a mathematician. Jane correctly reports that Joe says he is a mathematician, so Jane is definitely a mathematician. Jim says two things: "That's wrong," which presumably refers to Jane's statement (since he didn't hear Joe's). And then Jim says that Joe is a politician. Since Jane is not wrong in claiming that Joe said he was a mathematician, Jim must be lying. Ergo, there are two mathematicians. Jane and Joe are mathematicians, and Jim is a politician.
Jim is either a politician or a mathematician If Jim is a politician, then he's lying and hence Joe is a mathematician, so Joe whispers the truth to Jane, that he's a mathematician and she's reporting what he actually said to her, so she's also a mathematician. If Jim is a mathematician, then he's telling the truth, so Joe is indeed a politician and hence he lies to Jane, telling her he's a mathematician, but she's reporting what Joe actually whispered to her, so she tells the truth and hence she's a mathematician. In both cases, there are exactly two mathematicians.
No one here can ever say "I am a politician". A mathematician would be lying and a politician would be telling the truth. Therefore the blank must be filled "mathematician" and Jame is always telling the truth. That's one. If Joe is lying then Jim is telling the truth, and if Joe is telling the truth then Jim Is lying. Exactly one of the two males can ever be telling the truth. That's two, and done.
it will be easy if we listed down the clues: 1. a man will never claim that he/she is a politician since if one is a mathematician then he/she will have to tell the truth and claim that he/she is a mathematician, and if he/she is a politician, he/she will have to lie about he/she identity and therefore state that they were indeed a mathematician. 2. if Joe lies about his identity and Jane claims the fake identity that Joe has stated, Jane will not be considered lying since she is just doing what she was told to, tell everyone what Joe had whispered to her. ----------------------------------------------------------------------separation line--------------------------------------------------------------------- the breakthrough in the problem is that according to clue 1 we know that Joe must've told Jane that he is a mathematician and Jane is telling the truth and must be one of the mathematicians and from there on it separate into two situations: situation 1: Joe is indeed a mathematician and is telling the truth and Jane responded accordingly, leaving Jim as the politician since that he stated that Joe is a politician which in this case is false . ------> in this case, there is 2 mathematicians!! situation 2: Joe is a politician that is lying about his identity and Jane responded accordingly, leaving Joe as the second mathematician since that he stated that Joe is a politician which in this case is true ------> in this case, there is 2 mathematicians!! ---------------------------------------------------------------------------solution------------------------------------------------------------------------- you may have noticed already that in both situations there will be 2 mathematicians and is indeed the answer!! and always remember: failing is just another word for growing!! ˙ ͜ʟ˙
For clarification's sake it should be more clear that Jim is saying that what Joe said is wrong, not that what Jane said is wrong.
Either way you'll get the same answer, but it's important to understanding the problem.
Mathematician = 1 and Politician = 0
if Jane tells the truth ---> Jane = 1 Jim = 0 Joe = 1
if Jane tells a lie ---> Jane = 0 Jim = 1 Joe = 1
Joe's statement that he is either a politician or mathematician is a logically true statement based on the problem setup because if either is true, then that makes the statement true. Joe is a mathematician because he told the truth. Jane's statement is also true because Joe did claim that he was a mathematician (it's one of the inputs to the OR statement). This is true, so Jane is a mathematician. Jim said Joe's true statement (established above) is false, this is a lie. So, Jim is a politician.
I really like this. Except Joe does not state "I am either a mathematician or a politician." He makes one out of 2 possible statements.
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I see your point of view.
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In that case, then everything hinges on Janes statement. If Jane tells the truth, then there are 2 mathematicians, because she's telling the truth about Joe and Joe told the truth about being a mathematician. If Jane lies, then Joe is a politician and Jim is telling the truth as well, still giving 2 mathematicians
In simple form:
Since Joe said he was a Mathematician, Jane is also a Mathematician because she told the truth.
It doesn't matter whether Jim lies or not because there will still be 2 Mathematicians. If Joe lied by saying he was a Mathematician, Jim told the truth by saying he wasn't. If Joe told the truth, Jim lied. One of them has to tell the truth.
We have Joe, Jane, and Jim. And either of them could lying or telling the truth.
Joe will always have to say “I’m a mathematician” because either he is a lying politician or a truthful mathematician. This makes Jane’s statement automatically true, so she is a mathematician.
If Joe is lying, and is a politician, then Jim is right and is a mathematician. If Joe is telling the truth, then Jim is lying. So either Jane and Joe are mathematicians, or Jane and Jim are mathematicians.
In both scenarios there are two mathematicians, thus the answer.
Neither a politician nor mathematician can say "I am a politician", therefore Joe must have said "I am a mathematician". Therefore, Jane must be a mathematician.
If Joe is a mathematician, Jim must be a politition. If Joe is a politician, Jim must be a mathematician. Therefore there must be two mathematicians either way.
Whether Joe is a mathematician or not, he'll claim to be a mathematician. Thus Jane's statement is true, and she's a mathematician.
Joe's statement and Jim's statement are opposite to each other, therefore one is true and the other is false, i.e., one of the two is a mathematician and the other is a politician.
Thus we have two mathematicians.
If Joe were a mathematician he would be truthful and claim to be a mathematician. If he were a politician he would lie and claim to be a mathematician. Either way we know Joe claims to be a mathematician.
Therefore Jane's statement is true. Therefore Jane is a mathematician.
Jim claims Jane's statement is wrong therefore he is a politician. Therefore his second statement "Joe is a politician" is also false so Joe must be a mathematician.
Therefore 2 mathematicians, Joe and Jane.
We know for sure that Jane thinks she is better than Joe ( looking at the face while reading the line ), so that implies that Joe is saying "I am a mathematician" and also that Jane is a "better" mathematician. For Jim, we can easily tell that he is being sarcastic by his subtle smirk in his face , and also by the fact that he is looking away after Jane says her line.
--> There are 2 mathematicians , Joe and Jane.
Joe says he is a mathematician, because if he says he is a politician, than he would be telling the truth as a politician and lying as a mathematician, which can not happen. Jane reports he says he is a mathematician, so Jane is telling the truth. Now either Joe is a mathematician and Jim is a politician, or Joe is a politician and Jim is a mathematician. Both of these turn out to be 2 mathematicians.
We have to tackle this problem by breaking it down case by case.
First, let’s take the scenario A where Joe is a mathematician. 1) Jane claims that Joe is a mathematician, so Jane is telling the truth, thus she is a mathematician. 2) Jim would be lying by saying Joe is a politician.
Hence, the number of mathematicians is 2.
Second, let’s take the scenario B where Joe is a politician. 1) Joe has claimed to be a mathematician, so Jane would also be telling the truth, thus Jane is a mathematician. 2) Jim may correctly state that Joe is a politician, thus he is a mathematician.
So, the number of mathematicians is also 2.
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[Edit] First, we have to at least assume that Jim knows whether Joe is a politician or a mathematician, otherwise this problem is irresolvable.
If Joe is a mathematician, he would say that he is a mathematician. If Joe is a politician, he would say he is a mathematician.
If Jane hears Joe saying that he is a mathematician, and then reports that Joe claims to be a mathematician, then Jane is a mathematician.
If Jim is a mathematician, and knows that Joe is a politician, then he correctly states that Joe's claim to be a mathematician to be wrong, and that Joe is a politician. However, if Jim is a politician, and knows that Joe is a mathematician, he would have lied about it and said that Joe's claim to be a mathematician is wrong, and that Joe is a politician.
So, either
1) Joe is a politician, Jane is a mathematician, and Jim is a mathematician, or
2) Joe is a mathematician, Jane is a mathematician, and Jim is a politician.
Either way, there are 2 mathematicians present.