Q18 - A plausible explanation of the

[stephen.dewart]

I'm confused as to how (B) could possibly weaken the assertion that the comet (which collided into Earth) caused the demise of dinosaurs.

Within (B), I see an issue of scope. So what if animals of the same era with "similar" characteristics didn't become extinct at the same time as dinosaurs? Perhaps their physiology was SIMILAR but not 100% the same -- to me, it's like expecting a monkey and a human to experience the same circumstance because they share 99% ("similar") of DNA.

[ManhattanPrepLSAT2]

I think that you may be looking for a level of exactness that the test-writers don't intend with the questions --

Could it be that similar species didn't die out from the comets, even though dinosaurs did? Absolutely, and your human / monkey analogy is smart and right on --

However, we're not asked which answer will absolutely break the argument --

We're looking for an answer choice that most likely causes us to have significant doubt about the reasoning the author uses.

If (B) is true, and animals which were very similar to dinosaurs--notice, similar in ways that may be impacted by such a comet--didn't die out, it casts doubt on the comet theory. Again, it doesn't make it wrong, but it does make us doubt it.

None of the answer choices come even close to testing and making us question the reasoning the author uses --

There is another q that represents this type of uncertainty very well (and your example reminded me of it) comes just before this on in the same exam -- PT37, S4, q15 --

Remember, in particular for S/W, the right answer should DIRECTLY relate to a reasoning issue in the argument (i.e. b relates directly to the causation claim in the argument, which we should have suspected, before going into the answers, as being faulty), but doesn't have to be a clear and direct blow to the specific subject matter (i.e. can be about elements related to dinosaurs). This is slightly different from, say, a sufficient assumption q, for which you need much more absoluteness.

Hope that helps!

[schwingrocker]

Why is D wrong? I can see how B is a better answer, but that is the only reason why I picked B over D. Is there anything in particular that makes D wrong?

[timmydoeslsat]

It is just not strong enough. It absolutely weakens the argument to a certain extent, a very small extent. As I think you have implied, B takes answer choice D and bolsters it with much more pinpointed exactness (same era plus physiology and habitat).

[abcde]

Could someone explain why (A) and (C) are wrong?
I was able to eliminate (D) and (E) fairly easily.

(D) Many other animals species.... it really doesn't matter that other animals didn't become extinct because cool climate might not affect them the way it affected dinosaurs.

(E) the consequences for vegetation and animals.... is not really relevant to the fact comet colliding with Earth made the dinosaurs extinct.

On the other hand, I had some troubles choosing one among (A) (B) and (C) and these are the reasons.

(A) I thought it gave an alternate explanation of the dino extinction. Since the stimulus is saying "comet colliding Earth and thus cooling the climate by the dust cloud CAUSED the dino extinction, it creates cause and effect relationship. To weaken the stimulus, I was trying to find an alternative explanation of the dino extinction and thought (A) was a good choice because even though it's just one paleontology school that holds a different idea from comet theory, it is suggesting a different explanation of dino extinction. One thing I wasn't sure was that "significantly different" sounds vague to me to be called a real alternative explanation

(B) It looked really good at first, but I began to think that various species of animals that are similar in physiology and habitat to dinos aren't really related to the cause and effect relationship between comet collision and dino extinction. Those that are similar to dinos might have something that dinos don't have that helped them to survive through the cooled climate period.

(C) This also looked good to me. (C) is saying it cannot be determined from a study whether dinos died from the effects of a dust cloud (which means the cooled climate over long time). This choice throws a doubt just a bit by saying.. "i'm not sure whether what you are saying is true based on a study." It feels like it's trying to say the effect (dino extinction) MIGHT have happened without the cause (cooled climate) and that's why I thought (A) weakens the argument stronger than (C).


I'm sure I'm not correct since I got this question wrong, but I would love to hear where my reasoning strayed off the core.

Thank you.

[hychu3]

Hi, I'll try to explain (A), (B), and (D).

It's crucial to point out that the conclusion of the argument is simply that the comet theory is "plausible." I have to emphasize that the argument does not quite commit itself to the truth of the comet theory. This means that we have to attack the plausibility of the comet theory, not just the truth of it.

(A) By calling the comet theory "plausible," the argument does not rule out other explanations in any way. The mere existence of a "significantly different" theory, by itself, adds little to the argument.

We do not know how credible the explanation is, and how it is related to the comet theory. Perhaps both happened together and jointly contributed to the demise of the dinosaurs.

For (B) and (D), I believe both weaken the argument. There have been a very, very few Weaken/Strengthen Questions where two (or more) answer choices weaken/strengthen the argument, and this question is one of them.

However, in each of those cases, the test makers made sure one is definitely better than the other.

Here, (B) is definitely better than (D).

(D) says that many animal species from the same era as the dinosaurs did not become extinct.

In addition to saying what (D) says, (B) also says those those animals had similar physiology and habitat.

So, (B) is not so strong as a weakener, but it is still stronger than (D) and all other answer choices. So, (B) is the correct answer choice.

[ohthatpatrick]

Good response. Let me just add something to (A) and then address (C), which I think you also found tempting.

You were worried whether "significantly different" qualified as an alternative explanation. It DEFINITELY does. Even somewhat different may qualify as an alternative. But, just because an alternative explanation exists doesn't mean that the explanation we're considering has been undermined.

And as the previous poster brilliantly pointed out, we're only trying to address plausibility, so multiple schools of paleontology could simultaneously be considering multiple (and significantly different) plausible theories.

Your reaction to (B) was that it doesn't PROVE the original theory is wrong. You're correct. As you said, the similar species could easily have some non-dino trait that protected them from the comet cloud. BUT, our task in Strengthen/Weaken is never to prove or refute. So be very careful about playing devil's advocate to these answers. The correct answer to Str/Weak ALWAYS leaves room for either side of the argument to still be correct.

We have to judge them only in terms of whether they increase/decrease plausibility (no pun intended for this question's conclusion). (B) is DEFINITELY some good solid evidence that works against the theory.

The case you made for (C) kinda confused me. All (C) tells us is that dino bones do NOT offer us convincing proof that dinos died in from a dust cloud. Okay, well you could have also told me that a study of dino footprints cannot tell me whether dinos died from a dust cloud.

Does this weaken the theory? No, it just points to the limitations of how modern day scientists are able to investigate the theory. If they can't test the theory by looking at bones or footprints, they'll just have to test it some other way. This isn't a criticism of the theory; it's just an obstacle in the way of evaluating whether the theory is correct or not.

Hope this helps.

[WaltGrace1983]

Not to attempt to make blanket generalizations, but whenever we see answer choices showing that something "cannot be determined" (C) or "not fully understood" (E), can they really ever be correct in a strengthen/weaken question? It seems to me that such answers are basically saying, "I just made a causal argument and here is this piece of evidence....but I don't really know anything about it." I don't see how something like this can ever tip the scales in one direction or the other.

Anyone have any thoughts on this?

[maryadkins]

Totally depends on the stimulus.

If you have an argument where the conclusion is something like, "Rain is often the cause of flooding" and you had an answer choice that said, "The causes of flooding cannot be determined," that's a pretty good weakener. "Cannot be determined" and "not fully understood" poke holes, and sometimes, that's all it takes to weaken.