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Cats

by ssgmatter » Tue Mar 30, 2010 6:56 am
The interstitial nucleus, a subregion of the brain's hypothalamus, is typically smaller for male cats than for female cats. A neurobiologist perFORMed autopsies on male cats who died from disease X, a disease affecting no more than .05 percent of male cats, and found that these male cats had interstitial nuclei that were as large as those generally found in female cats. Thus, the size of the interstitial nucleus determines whether or not male cats can contract disease X.

Which one of the following statements, if true, most seriously weakens the argument?

(A) No female cats have been known to contract disease X, which is a subtype of disease Y.

(B) Many male cats who contract disease X also contract disease Z, the cause of which is unknown.

(C) the interstitial nuclei of female cats who contact disease X are larger than those of female cats who do not contract disease X.

(D) Of 1,000 autopsies on male cats who did not contract disease X, 5 revealed interstitial nuclei larger than those of the average male cat.

(E) The hypothalamus is known not to be causally linked to disease Y, and disease X is a subtype of disease Y.

Please explain this is hieghts...

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Phil
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by aspirant2010 » Tue Mar 30, 2010 7:21 am
Is the answer D......
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by ssgmatter » Tue Mar 30, 2010 7:43 am
please explain i will post the OA asap

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Phil
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by akahuja143 » Tue Mar 30, 2010 7:50 am
IMO D

Conclusion is based on evidence
a disease affecting no more than .05 percent of male cats, and found that these male cats had interstitial nuclei that were as large as those generally found in female cats.


If we can show that is not reliable or flawed then argument will fall apart

D does it

(D) Of 1,000 autopsies on male cats who did not contract disease X, 5 revealed interstitial nuclei larger than those of the average male cat.

5 out of 1000 is .05 % and let us know that this is common irrespective of the diseases
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by Phirozz » Tue Mar 30, 2010 8:37 am
IMO E

A, B AND C can be easily eliminated.
now D, does the author saying anything about cats who do not contract disease X ? NO. So it neither weaken nor strengthen the argument

Now come to E, it is clearly attacking the conclusion. Since X is a subtype of disease Y, hypothalamus should link to Y as well but it does not. So it weaken the argument
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by Testluv » Tue Mar 30, 2010 1:09 pm
recieved a pm.

Phirozz is correct.

When the author makes a causal argument, the author is making any one (or more) of the following assumptions:

a) that there isn't an alternative cause;
b) that it isn't a coincidence; and
c) that causality isn't reversed (although this applies only to simutltaneous rather than chronological correlation).

Of these three, by far the most common is a. The second most common is b. We can weaken the argument by attacking any one of these assumptions.

Here, choice E tells us that we are in "b": since the hypothalamus is KNOWN not to be causally linked to disease X, the statistics are just a coincidence. Thus, choice E clearly weakens the argument, and must be correct.

Because choice E matches our prediction, we should select it without worrying about choice D--on test day, we have to be confident.

But, while reviewing our performance, we should figure out why tempting wrong answers are wrong.

Choice D tells us that 5 percent of male cats had nuclei that were larger than the average male cat nuclei. But we are left wondering whether these nuclei are as large as female cat nuclei. Thus, choice D does not successfully weaken the argument.
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by ssgmatter » Wed Mar 31, 2010 7:24 am
Thankyou Testluv for that such an exhaustive analysis.

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Phil
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by ru2008 » Wed Mar 31, 2010 8:30 am
Could you explain why A,B,C, E is wrong?
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by Testluv » Thu Apr 01, 2010 4:27 pm
ru2008 wrote:Could you explain why A,B,C, E is wrong?
Choices A and C are wrong because the author is making an argument about male cats not female cats. In other words, it is outside the scope of the author's argument. Thus, it cannot weaken this argument.

Choice B is wrong because we have no idea about how to evaluate the relevance of the correlation between disease X and disease Z. In other words, it is outside the scope.

I explained why choice D is wrong in my post above.

You are far better off analyzing the argument correctly, and predicting the correct answer, than you are figuring out why all of the wrong answers are wrong. However, when reviewing it is a great idea to articulate why wrong answers are wrong.
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by prepgmat09 » Fri Jul 30, 2010 3:57 am
Testluv wrote:recieved a pm.

Phirozz is correct.

When the author makes a causal argument, the author is making any one (or more) of the following assumptions:

a) that there isn't an alternative cause;
b) that it isn't a coincidence; and
c) that causality isn't reversed (although this applies only to simutltaneous rather than chronological correlation).

Of these three, by far the most common is a. The second most common is b. We can weaken the argument by attacking any one of these assumptions.

Here, choice E tells us that we are in "b": since the hypothalamus is KNOWN not to be causally linked to disease X, the statistics are just a coincidence. Thus, choice E clearly weakens the argument, and must be correct.

Because choice E matches our prediction, we should select it without worrying about choice D--on test day, we have to be confident.

But, while reviewing our performance, we should figure out why tempting wrong answers are wrong.

Choice D tells us that 5 percent of male cats had nuclei that were larger than the average male cat nuclei. But we are left wondering whether these nuclei are as large as female cat nuclei. Thus, choice D does not successfully weaken the argument.
Hello Testluv, Thanks so much for the wonderful explanation.

However, I still have a doubt with choice D. Sometimes, an approach to weaken a cause and effect argument is to show that the effect is not there even when the cause is there. D is also doing that, although I agree that with D we are left wondering whether these nuclei are as large as female cat nuclei.

So, should we still consider this choice as "slightly weaken".
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