A - lean young adults. B - people who live long. C - adults who gained one pound every year.
Premise: B tend to have been (usually are) A who became C. B=A+C
Conclusion: A can become B if they become C too. A-> B, if A+C

A. reasons for the truth of conclusion (premise) presupposes (requires) the truth of conclusion. No, premise does not require the conclusion to be true. Rather, the conclusion is clearly derived from the premise.
B. there is no guarantee in the argument anywhere. 'Tends to' does not indicate a guarantee.
C. Proof is provided. Also, it is unclear which two phenomena occur together and which one is the cause? A and B do not occur together. There is a 'if' relationship between A and B which makes them sequential.
D. Correct. Concludes that combination of A and C causes B, whereas 'tends to' in the premise indicates only a weak association. So does 'can improve' in conclusion.
E. The conclusion restricts itself to lean people. Population as a whole is not referred to anywhere in the argument.

OA is D. I thought this one was very tough b/c many of the answer choices seem to fit the bill of what is being asked.

it is very straight forward D , though E created a bit of confusion . i think less than 2 minutes is ok for this question

the stem has a construction - since A tends to B so B must tend to A.
this is faulty and both options B and D seem to fit the bill.
i chose D though since it seemed better,but still need clarification why B is wrong.

Why is B wrong?


It fits perfectly for me;

one pound each year -> live long

The flaw is that the author does not explain why one pound each year is the cause. It might be the effect of another cause, or there might be something else so there is a flaw of logic because the author does not make this cause as self sufficient to live longer...

Explanation please!

here we see a cause and effect pattern that is -X (Lean young adult who gain app one pound per year) ---- Y (Adults live longer). but the conclusion says that the reverse causation is also true and hence option D is correct.

People who live unusually long tend to have been lean young adults who went on to gain approximately one pound every year, so lean young adults can improve their chances of living a long life by gaining about a pound every year.
A flaw in the argument above is that it

(B) proceeds as though a condition that by itself is enough to guarantee a certain result must always be present for that result to be achieved

(D) concludes that one phenomenon is the cause of another when at most what has been established is an association between them


Although D can be credited as correct, B has a more logical reasoning.
mikemcgarry,

Would you please assist in understanding why is B wrong?
Thank you
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Hi TaN1213,

Carolyn from Magoosh here -- I can step in for Mike

The wording here is all a bit complicated here, so it's important to really read the answer choices carefully. When we do that, we find that B does not quite fit the situation that we're talking about. Let's think about this argument. There is an observation that people who live for a long time started out lean and then gained about a pound every year. So there is an association made: gain one pound every year <--> live long. The argument then says that if someone wants to live long, they should gain one pound every year. In order to make that conclusion, we need to turn that association into a cause-and-effect: gain one pound every year --> live long. This, of course, is a fallacy. And that fallacy is perfectly described by option D here.

Now, B is talking about a condition that must be present in order for a result to be achieved. Look at the first part: "a condition that by itself is enough to guarantee a certain result". What is that condition, in this context? There isn't one -- we don't know of any condition here that by itself will guarantee that someone will live long. We know that there is an association with gaining one pound every year, but we certainly can't say that this is guaranteeing that someone will live for a long time. So even without reading the second half of B, we know that this answer choice cannot be correct. There simply is no condition mentioned here that by itself can guarantee that someone will live for a long time.

I hope that helps!
-Carolyn
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Hello Carolyn,

Please find my understanding of B :
[combining the question stem and option B]
A flaw in the argument above is that it "proceeds as though a condition that by itself is enough to guarantee a certain result must always be present for that result to be achieved"

The B states the flaw as though(assuming) the following is correct :
The action of gaining approximately one pound every year(a condition) that by itself is enough to guarantee a longer lifespan (a certain result) must always be present for actually getting a longer lifespan(result to be achieved).

The bold 'as though' part is the flawed assumption that is stated in B. For example: Everyone greeted Garry as though he is the owner of the casino. This is the flawed assumption implied by 'as though'. It does not mean that this sentence is telling that Garry himself was the owner of the casino. Similarly, B is not talking about a condition that must be present in order for a result to be achieved. B states the flaw.


By the way, just wondering where is Mike. Since quite many days, I haven't had seen him around in the gmatclub. I hope he is doing well.

Thank you.
GMATNinja, your insight is much appreciated.
Thank you.
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B is wrong b/c B talks about if and only if.
A is wrong b/c the argument does not present the conclusion to the premise.
C is out b/c there is only one phenomenon.
E is not obvious but I believe E is wrong b/c the argument talks about the population first with a tendency, and then a subgroup later.

D is a pattern in gmat: "relation vs cause"

Hi TaN1213,

Mike is currently working on other projects at Magoosh, and so won't be posting on GMATclub much for now.

Thanks for clarifying your reasoning Let's use a different example to understand this better, since the wording here can get a little complicated. Say we have a statement like:

John incorrectly assumes that his ice cream, which is chocolate, is dairy-free.

Now, the incorrect assumption here is that the ice cream is dairy-free. It is NOT that the ice cream is chocolate. The fact that the ice cream is chocolate is not part of his assumption -- it is something that this statement is assuming is fact. So according to this statement, there is no question that the ice cream is chocolate. If the ice cream is not in fact chocolate, then this entire statement no longer applies, because it does not match the situation. If John's ice cream is vanilla, this statement doesn't make sense. His assumption is only that the ice cream is dairy-free.

Now let's look at our actual statement:

B assumes that the action of gaining approximately one pound every year (a condition) that by itself is enough to guarantee a longer lifespan (a certain result) must always be present for actually getting a longer lifespan (result to be achieved).

So, the "which is chocolate" part is analogous to "that by itself is enough to guarantee a longer lifespan". It is NOT part of the assumption -- it is something that must be true in order for the statement to make sense. However, this is not true. Gaining approximately one point every year is NOT enough to guarantee a longer lifespan by itself. This is like saying that John's ice cream is vanilla. It makes the entire statement irrelevant to our situation, because it is simply not true. Here, the only assumption is that the action of gaining approximately one pound every year must always be present for getting a longer lifespan.

In your second example, there isn't an analogous part. Let's modify it to say: Everyone greeted Garry as though he is the owner of the casino, since he spends so much time gambling. The assumption here is still just that Garry is the owner of the casino. The fact that he spends so much time gambling is NOT part of the assumption -- it is something that must be true in order for this statement to apply. So let's say that Garry actually never gambles. Then, this statement will simply not apply; it no longer makes any sense. If Garry never gambles, then it's not that people are making an incorrect assumption -- the facts are just totally wrong.

Does that help to clear things up any more here? If not, let me know
-Carolyn
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The argument says that people who were lean young adults and gained 1 pound a year lived unusually long. Based on this the author concludes that lean young adults can live longer by gaining 1 pound a year. The author here links 2 events that occurred on the same set of people as though 1 event caused the other but the 2 events even though observed on the same set people could be correlated but not have causal relation. This is what option D says.

People who live unusually long tend to have been lean young adults who went on to gain approximately one pound every year, so lean young adults can improve their chances of living a long life by gaining about a pound every year.

A flaw in the argument above is that it

(A) gives reasons for the truth of its conclusion that presuppose the truth of that conclusion
[A seems to say that the conclusion (live long) is true before conclusion is verified. Since it is a flaw question, Stimuli info are not in question, argument structure is: shouldn't have to question the facts. Incorrect]

(B) proceeds as though a condition that by itself is enough to guarantee a certain result must always be present for that result to be achieved
[B states the flaw in argument is that stimulus asserts that condition (lean and gain weight) --> result (live long) and no other alternative condition is possible. However, stimulus used "tend" and "improve", which are not 100% probability words. So B is not a flaw. Incorrect]

(C) assumes without proof that two phenomena that occur together share an underlying cause
[Does not matter to the argument, argument did not state that the two phenomena share a cause. Incorrect]

(D) concludes that one phenomenon is the cause of another when at most what has been established is an association between them
[Stimulus states (live long)-->(lean + gain weight) as evidence for conclusion of (gain weight + lean) --> (live long). This is a flaw of mistake reversal. Also could be assuming causal relationship from correlation. Either way, that is the flaw of the argument. Correct]

(E) fails to recognize that a tendency widely shared by a subgroup within a given population will not necessarily be widely shared by that population as a whole
[Stimulus argument's flaw is not a flaw of composition as the evidence and results are both targeted at the same subgroup of population: lean young people. Incorrect]

Hope this helps

People who live unusually long tend to have been lean young adults who went on to gain approximately one pound every year, so lean young adults can improve their chances of living a long life by gaining about a pound every year.

A flaw in the argument above is that it

(A) gives reasons for the truth of its conclusion that presuppose the truth of that conclusion - Incorrect

(B) proceeds as though a condition that by itself is enough to guarantee a certain result must always be present for that result to be achieved - Incorrect - we are told about a correlation and it has not been mentioned as necessary condition

(C) assumes without proof that two phenomena that occur together share an underlying cause - Incorrect - no such underlying cause is mentioned

(D) concludes that one phenomenon is the cause of another when at most what has been established is an association between them - Correct - this explains correlation vs causation

(E) fails to recognize that a tendency widely shared by a subgroup within a given population will not necessarily be widely shared by that population as a whole - Incorrect - this option seems incorrect if we consider the population as all adults (or humans) and the subgroup within a given population refers to lean young adults.

But what If we consider the population as the lean young adults and the subgroup as the population of lean young adults with a tendency to gain approximately one pound every year and thus live a long life? Won't E make sense then?

AjiteshArun , GMATNinja , MagooshExpert , GMATGuruNY , VeritasKarishma , DmitryFarber , ChiranjeevSingh , RonPurewal , VeritasPrepBrian , MartyMurray , ccooley , other experts - please enlighten
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When they say "people who...", we should look at that group as all people who live unusually long. Many, but not all, people in this group were generally lean when they were young adults, and they had gained ~1 pound every year. So we can't say that the population consists of only those people who were lean as young adults.
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AjiteshArun
Can you please brief the option A ?
I didn't even understand the option

When we say something like the premise presupposes the truth of the conclusion, what we mean is that the premise takes the conclusion as a given. For example:

A high GMAT score is essential because it is necessary to get a high GMAT score.
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This question deals with an issue that is commonly taught in business schools: Correlation does not imply causation.

It is not because 2 phenomenon tend to follow the same direction that 1 is the cause of the other.
Hence answer D.

Hope it helps