Q25 - The interstitial nucleus, a subregion

[lisahollchang]

This problem was pretty difficult for me. I ended up deciding between answer choices B and E, and incorrectly chose B. Can anyone help clarify why E is the correct answer choice? Thanks!

[cyruswhittaker]

The conclusion asserts that there is a causal relationship between the size of the nucleus and whether the male cats can contract disease X.

Choice E attacks this causal relationship by providing evidence that the hypothalamus (which contains the nucleus) is not causally linked to disease Y. Since X is a subtype of disease Y, this provides some evidence that there might not be a causal link to X either.

[lisahollchang]

Thanks! I guess the wording of the stimulus and answer choices was weirding me out with this one.

[clarafok]

Hello,

I'm still really confused because I don't understand how Y plays a role. I chose D instead thinking that the stats would weaken the argument.

Could someone please further clarify this for me??

Thanks in advance!

[ManhattanPrepLSAT1]

There are many questions on the LSAT that I love. This is not one of them. It almost feels as if the man in a cubicle writing this question was feeling a bit sneaky. The wording in the correct answer is different (maybe even a bit weird) but adequate. Here's how I suspect they see it.

The size of the interstitial nucleus (a subregion of the brain's hypocampus) is correlated with disease X. The argument concludes that the interstitial nucleus is causally connected with disease X. We're all taught that on the LSAT to undermine causation we simply offer an alternative cause. Answer choice (B) does this. So why isn't it the answer? The reason is that the correlation between disease Z and disease X isn't strong enough. "Many" is sometimes thought of by students as "most." Really it's just "some." And some could be just a couple. Not much of an alternative cause it might only affect a few of those who have disease X.

Answer choice (E), however awkward, would ensure that there is no causal connection between the size of the interstitial nucleus and disease X. It walls each factor off into larger ideas that are then said to be not causally connected.

I know that's sort of a long explanation, hope it helps!

[clarafok]

that was very helpful! thank you!

i can't wait to burn all my LSAT books!

[niohelang]

Hi I am still curious about the question.Especially why the answer choice D is incorrect.
When we attack a causal argument, except for giving an alternative cause, we also do so by providing a condition where the cause or the effect happens while the effect or the cause does not.
So in choice D, the cause (the interstitial nuclei is larger than the average) happens yet the 5 male cats didn't contract disease X (the effect didn't happen). Why is it wrong?

Do need help!
Thanks.

[sumukh09]

D says "larger than those of the average male cat" however we don't know how the average size of the interstitial nuclei of a male cat compares to that of the female cat so we can't make the assumption that the 5 cats described in this answer choice had interstitial nuclei as large as a female cat. Remember that the disease is contracted by male cats who have generally as large an interstitial nuclei as female cats, so it's unclear whether the having interstitial nuclei larger than the average male cat is sufficient.

[redcobra21]

Thanks for the great response Matt! That definitely helped a lot.

One question I have about (E) is that it strikes me as committing a part-to-whole fallacy.

The stimulus is saying: Part of the hypothalamus CAUSES Subset of Disease Y

The answer choice is saying: The whole hypothalamus DOES NOT CAUSE whole of disease Y

My question is: Can't a part of the hypothalamus still cause a part of disease Y even if the whole of the hypothalamus does not cause the whole of disease Y? Or am I looking at this wrong and this is an acceptable tactic on an issue of causation?

Thanks in advance for your help

[ManhattanPrepLSAT1]

Great attention to the difference between a whole and its parts. And while it seems possible that the part (interstitial nuclei) of the hypothalamus might still be responsible for causing disease X (a part of disease Y), it seems unlikely given that the hypothalamus (the location of the interstitial nuclei) is known not to cause disease Y (a category of disease to which disease X belongs).

Is it possible? Sure. Is it undermined by the information in answer choice (E)? Absolutely. And that's the only task set out for us in the question stem.

[mkd000]

I'm still having trouble with this one. Why is (D) incorrect? I am having trouble seeing any of the answer choices as correct. Initially, I thought (E) was incorrect because disease Y is out of scope. For example, if lung cancer is a subtype of cancer, and cigarette smoking does not have a causal link to cancers in general, it can still have a causal connection with lung cancer. I picked (D) after eliminating all other choices, and because I thought if non-disease X cats have larger IN, then it is not nec the case that IN is causally connected to disease X. I later realized (D) is incorrect b/c the stimulus states "typically" (aka, it is not that large IN is sufficient for disease X, so some may have large IN without disease X).

please help me understand why (E) is correct! The above explanations have not helped me enough. Thanks!

[maryadkins]

(E) is the best choice of the five. It sounds like you have a good understanding of what (E) is doing so I don't think that lack of understanding is the problem. It's just a crappy question and frankly in that regard not a good one to try to extract a lesson from. The only lesson I would suggest you take away from this is the importance of process of elimination, and perhaps to remember that you're choosing the best of the five. (E) at least attacks the causation issue, albeit in an imperfect way.

[Heart Shaped Box]

[quote="mkd000"]I'm still having trouble with this one. Why is (D) incorrect? I am having trouble seeing any of the answer choices as correct. Initially, I thought (E) was incorrect because disease Y is out of scope. For example, if lung cancer is a subtype of cancer, and cigarette smoking does not have a causal link to cancers in general, it can still have a causal connection with lung cancer.

If smoking does not cause cancer at all/in general, how can it still cause lung cancer? Lung cancer is a subset of cancel, and smoking doesn't cause cancer, "period", hence does not cause lung cancer either. And E explicitly states just that.

[ZarkaS555]

I think answer choice D is incorrect because it really doesn't help us weaken the argument. The author claims that "the size of the interstitial nucleus determines whether or not the cats CAN contract disease X", implying that the nuclei can lead one to contract the disease in the present or in future. All answer choice D tells us is that of the 1000 cats that did not contract disease X, 5 had interstitial nuclei larger than the average male cat. Great for these cats now, but does this tell us that they can't get disease X? No. Does it tell us that they won't EVER get disease X in the future? No. Despite the tests, CAN they still get disease X? Sure.

Am I on the right track with this?

[ohthatpatrick]

Correct. The truth value of the conclusion is about whether interstitial nucleus size determines whether you CAN contract disease X, not whether you HAVE CONTRACTED disease X.

I also found it unappealing because "larger than those of an avg male cat" is not a very interesting thought.

We aren't hearing that it's as large as those of the female cat (so it's not easy to compare these data points to the ones discussed in the stimulus).

And the stimulus left room for the idea that some male cats have larger I.N.'s than others, by saying the male's I.N. is "typically" smaller than that of a female cat.

Finally, this is such a small sample to off of, it will have limited strength as a weakener. It could still be the correct answer if none of the other answers weakened. "SOME weakening effect > NO weakening effect".

But comparing this to (E), which COMPLETELY UNDERCUTS the plausibility of the conclusion, there's no doubt which answer MOST WEAKENS.

[Yu440]

Hello,

If answer D said: "of 1000 autopsies on male cats who did not contract disease X, 500 revealed interstitial nuclei larger than those of the average female cat", would it be a more enticing choice? Thanks!

[ohthatpatrick]

Yes it would be a much stronger answer. It still wouldn't be as strong as (E), because (E) essentially kills the conclusion from having any chance at being right.

However, your amended (D) would also be going against a premise (male cats typically have smaller IN's than female cats). In a sample of 1000 male cats, we should be seeing that at least 501 of the cats have IN's that are smaller than those of female cats).

So it would be a very unlikely answer for LSAT to write.

[jongoned770]

Yes it would be a much stronger answer. It still wouldn't be as strong as (E), because (E) essentially kills the conclusion from having any chance at being right.

However, your amended (D) would also be going against a premise (male cats typically have smaller IN's than female cats). In a sample of 1000 male cats, we should be seeing that at least 501 of the cats have IN's that are smaller than those of female cats).

So it would be a very unlikely answer for LSAT to write.

The reason why I didn't choose (E) was that (E) just says "is known not to be"; I think 'being known not to be causally linked' does not imply "being not to be causally linked". For example, suppose that I want to find the culprit of a murder case, and I suspect David. But someone says that David is not the culprit because David is not known to be the culprit of the murder case. Does the fact that David is 'not known' to be the culprit really weaken the conclusion that David is the culprit? I don't think so.
Can someone correct my reasoning here? Many thanks.

[Laura Damone]

Sure thing!

The problem with that reasoning is that "David is not known to be the murderer" isn't the same as "David is known not to be the murder."

The order of that phrase really matters! If David is not known to be the murder, that means we don't know that he is the murderer.

If, on the other hand, he is known not to be the murderer, that means we know he's not the murderer.

Hope this helps!
Laura