GMAT Prep: fullerenes.

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capnx
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Topic: GMAT Prep: fullerenes.
PostFri Nov 06, 2009 12:36 am
I don't see the relevance of any of the choices... Please explain.
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PostFri Nov 06, 2009 3:19 am
Hi capnx,


The author's evidence has established that the labaratory conditions leading to fullerenes are unique. He also tells us that we have now found fullerenes in nature (shungite stuff is red herring).

He is arguing that because lab-fullerene-formation requires unique conditions, we can examine these new natural fullerenes to figure out what the conditions in the Earth's crust were like back when these fullerenes were formed.

He is assuming that fullerenes everywhere (ie, the naturally occuring ones, outside of the labaratory) also come about through unique conditions. (It might just be the case that it is only in the labaratory that unique conditions are required or that they have yet to hit upon other ways of making fullerenes in the lab).

We can use the Kaplan denial test to verify whether we have figured out the assumption correctly: what if, outside of the lab, there are many ways that fullerenes can be formed? Then, what happens to the argument that we can examine these naturally ooccuring fullerenes to figure out what the conditions were like when they were formed? Well because there are many was they could have formed, and who knows what the conditions were like back then: the argument now falls apart. Therefore, we have properly identified a necessary assumption.

..now (and only now) are we ready to go to the answer choices.

Because this is a weaken question, we look for a choice that attacks this assumption. Choice D opens up the possibility of fullerenes forming in ways unknown in the lab, and is correct.

In a harder argument, it is very important to resist the temptation to go to the answer choices prematurely. Gotta analyze the stimulus and figure out how, precisely, the evidence is not good enough to estalish the conclusion. Gotta figure out that assumption!

Make sure you always ask what idea is in the conclusion that is not in the evidence and what idea is in the evidence that is not in the conclusion, and then bridge the gap. This is the classic Kaplan method for arguments.

Applied here:

What idea is in the evidence that is not in the conclusion? "lab fullerenes"

And the idea in the conclusion that is not in the evidence? "naturally occuring fullerenes".

Then bridge the gap: "The author is assuming some sort of similarity between the two. The argument is about unique conditions, so he is assuming that conditions are unique for both lab and natural fullerenes."
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capnx
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PostFri Nov 06, 2009 8:03 am
Thank you Testluv. I didn't fully grasp the initial argument (assumptions and conclusions) so that's what made it difficult for me. Your explanation is very detailed. THanks.
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PostFri Nov 06, 2009 8:04 am
@Testluv,I took sometime to understand ur Point of view.. U did gave a solid explanation & rightly construed the agrument.

That Shungite is a redherring..

As per ur wrds,If we negate the assumption on which the conclusion is made,that serves the purpose of weakening the argument...

Many Thx Testluv!!

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PostSat Nov 07, 2009 9:49 pm
Quote:
As per ur wrds,If we negate the assumption on which the conclusion is made,that serves the purpose of weakening the argument...

Hi gmatmachoman,

that's not quite what I meant.

In a weaken question, an answer choice that completely negates the assumption is definitely a weakener.

BUT, in order to weaken an argument, an answer choice does not necessarily HAVE to negate the assumption, and nor will it be likely to.
("Negate" = "Deny" = remove from existence).

The right answer DOES have to attack the assumption--tend to refute it. This is because the definition of weakening is: making an argument less likely to be true. (However, the weakener will almost always clearly target the assumption.)

The reason I used negation test in my explanation above was a little bit different from usual. Because the argument was difficult, and because it may have been a bit tough to identify the assumption, I pointed out that we could make of use the denial test as a check (to verify) that you have identified the correct assumption.

In other words, you can, if you want, figure out the assumption, and then use denial test to verify it in your head before you look at ANY answer choices.

After I finished doing that, my prediction was this: "The author is assuming that naturally occuring fullerenes are just ike the lab ones--they need unique conditions to come about. Because this is a weaken question, I will aggressively scan for a fact that will attack this assumption."
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PostSun Nov 08, 2009 3:13 am
Testluv,

If I understood the above explanation correctly,

1. It means that negating an assumption is not the NECESSARY condition for weakening the argument.

2. It is SUFFICIENT on the part of the answer choice that when denied, it tends to weaken the assumption. Hence it is the right answer choice that weakens the argument!

Hope I'm right!
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PostSun Nov 08, 2009 3:45 pm
raghavakumar85 wrote:
Testluv,

If I understood the above explanation correctly,

1. It means that negating an assumption is not the NECESSARY condition for weakening the argument.

2. It is SUFFICIENT on the part of the answer choice that when denied, it tends to weaken the assumption. Hence it is the right answer choice that weakens the argument!

Hope I'm right!
Yes, you are right!
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Testluv
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PostSun Nov 08, 2009 6:32 pm
Testluv wrote:
raghavakumar85 wrote:
Testluv,

If I understood the above explanation correctly,

1. It means that negating an assumption is not the NECESSARY condition for weakening the argument.

2. It is SUFFICIENT on the part of the answer choice that when denied, it tends to weaken the assumption. Hence it is the right answer choice that weakens the argument!

Hope I'm right!
Yes, you are right!
Wait a second, maybe you're not!

"It is SUFFICIENT on the part of the answer choice that when denied, it tends to weaken the assumption. "

If it is a weaken question, it just has to attack the assumption directly (not after denial!).

In fact, if you're in a weaken question, and a DENIED choice STRENGTHENS, then that is the right answer. (Because, strengtheners are weakeners are, of course, opposites.)
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