Q10 - All of John's friends say

[ali.charania]

I don't know how to approach this questions so could someone please post an explanation and walk me through the answer choices?

Thanks!

[timmydoeslsat]

I would always advise to read the question stem first. We have a must be true question stem.

I typically diagram these types of question stems, but in this case, it does not call for it.

We know that every friend of John's has stated they know someone who has smoked a lot and is well.

John does not know a single person like that. We are told that John is not unique among his friends in this fact.

If John is not unique among his friends in this respect, it is impossible for none of his friends to be like him. There must be at least one that is like him -- which is to say that they do not know of a person that smokes that much and is well.

A) This is attempting to make you think that the friends have been tricked into believing a smoker. The fact is that the friends say they know a type of person. John says he does not know that type of person. We are told that John is not unique in that respect amongst his friends. In short, we have no idea whether smokers often lie about how much they smoke.

B) Not something that is provable, a must be true situation. We do not know whether the friends did not intend their lie or not.

C) Must it be true that all of these friends know the same smoker? Of course not.

D) Most?

E) Some, yes. Answer choice D goes too far logically. We know that some are. Think about it this way. If it were true that most most, wouldn't it also be true that some are?

[marshal_of_grey]

The problem I had with this question is knowing which of the claims we were able to treat as true. Why is what "John's friends say" suspect when what "John...is quite certain" about can be taken as fact?

I chose the correct answer, but this was my analysis: the stem says "if the statements are true." The statement about the friends is that they said they know someone; the statement can be true even if the friends are lying because the statement is only that they said something, not that they were truthful in saying this thing. But I don't exactly see why if John is "quite certain" about something that this thing must also necessarily be true. It seems to me that you can truthfully be certain but also be wrong. I could be quite certain that I will get a 180 but I could at the same time be wrong and get a 165 (heaven forfend). The question relies on the fact that John is correct when he supposes that he is not "unique." But if we cannot rely on this deduction, as I suggest we cannot, the question cannot be solved given the answers.

It was close enough that I was able to conclude that this was what the LSAT was wanting me to deduce, particularly given that the other answers were identifiably wrong, but I'm not convinced it's an airtight assumption. Given that my confusion arises from what seems to be an uncertainty over how the LSAT views reliable statements, and thus my confusion could lead to further mistakes, help?

[ManhattanPrepLSAT1]

Here's a general rule of thumb that I use about the the issue of whether something is true.

If it reads, John "knows" or "is certain" that ______ is true, then it is true.

If it reads, John "believes" or "thinks" that _______ is true, then it may be true, or may not be.

In this case it states that John is certain. The issue is that John's friend know something too! But in this case, the "know" is more about being familiar with something, rather than being certain about something. Furthermore, it doesn't just say that John's friends "know" something, but it says that John's friends "say" they know something.

That gives us two reasons to question what John's friends say. Since John's statements are phrased more certainly, and we are told to believe the statements. We know that John is certain about something, and that John's friends say something that contradicts what John is certain about. That leads to the inference that at least some of John's friends are not telling the truth--expressed in answer choice (E).

Remember, "thinks/believes" = may be true, or may not be. "Knows/certain" = is true.

Incorrect Answers
(A) incorrectly attributes the incorrectness to the smokers when it should be attributed to John's friends.
(B) is a bit too specific in that we are not sure what intention of John's friends is.
(C) could be true, but need not be. Furthermore, we're actually given information that the person/s that John's friends say they know is not known by all of John's friends.
(D) is too extreme. Not being unique means that there is at least one of John's friends that does not know such a person, but this will not justify that most of John's friends do not know such a person.

[hanhansummer]

Here's a general rule of thumb that I use about the the issue of whether something is true.

If it reads, John "knows" or "is certain" that ______ is true, then it is true.

If it reads, John "believes" or "thinks" that _______ is true, then it may be true, or may not be.

In this case it states that John is certain. The issue is that John's friend know something too! But in this case, the "know" is more about being familiar with something, rather than being certain about something. Furthermore, it doesn't just say that John's friends "know" something, but it says that John's friends "say" they know something.

That gives us two reasons to question what John's friends say. Since John's statements are phrased more certainly, and we are told to believe the statements. We know that John is certain about something, and that John's friends say something that contradicts what John is certain about. That leads to the inference that at least some of John's friends are not telling the truth--expressed in answer choice (E).

Remember, "thinks/believes" = may be true, or may not be. "Knows/certain" = is true.

Incorrect Answers
(A) incorrectly attributes the incorrectness to the smokers when it should be attributed to John's friends.
(B) is a bit too specific in that we are not sure what intention of John's friends is.
(C) could be true, but need not be. Furthermore, we're actually given information that the person/s that John's friends say they know is not known by all of John's friends.
(D) is too extreme. Not being unique means that there is at least one of John's friends that does not know such a person, but this will not justify that most of John's friends do not know such a person.

I still have a problem. If all of John's friends say something that contradicts with what John is certain about, and if what John is certain about is true, then why can't we have "all of John's friends are not telling the truth"? Is that because John personally is certain about something but that could still be wrong. So it would be more provable to have "some of his friends are not telling the truth".

[ahaghgoo]

If John was the person who smoked 40 cigarettes a day for the past 40 years and was really fit and well, wouldn't that allow for answer choice C to be correct and the rest of the answer choices false? This was one of the types of stimuli that I feel like falling into a manhole because I didn't see what I needed to see which wasn't evident from the stimulus. Still figuring out how to address this…