Q21 - Essayist: when the first prehistoric

[mitchliao]

Is answer choice (C) correct because in some cases there was there was no cause - (not exposed to microogranisms) but the effect occurred - (extinction in these few species)? If I'm totally off, what's your line of reasoning?

Also, why is answer choice (D) not the correct answer? Is it because one doesn't know if the cause (exposure to microorganisms) occurred in this set of species? Therefore, one can't tell how (D) effects (strengthens or weakens) the cause and effect relationship?

Thanks for your help in advance!

[giladedelman]

Thanks for posting.

The essayist concludes that the the cause of the North American extinctions was disease-carrying microorganisms brought over by prehistoric humans and the animals that followed them. He bases that on the premise that such microorganisms were definitely brought over, and dismisses an alternative explanation -- hunting -- as "implausible."

(C) weakens the argument by undermining that last judgment. If very few animals that were not hunted became extinct, then it seems likely that hunting, rather than disease, was the cause of the extinctions. This is precisely the alternative explanation that the argument dismisses.

(A) strengthens the argument by supporting the idea that disease could have caused the extinctions.

(B) is out of scope. Whether humans are immune is irrelevant.

(D) is out of scope too; like you said, it doesn't effect the argument. It doesn't help us answer the question of what caused the extinctions!

(E) is incorrect because we don't care whether "some" species of animals (how many? two? three?) became extinct later. We want to explain why the ones in the argument became extinct.

Does that answer your question?

[mitchliao]

Thanks so much for the help. I really appreciate it. I have a couple of follow up questions though.

(C) weakens the argument by undermining that last judgment. If very few animals that were not hunted became extinct, then it seems likely that hunting, rather than disease, was the cause of the extinctions. This is precisely the alternative explanation that the argument dismisses.

My first question is: Are you suppose to assume the premises in the question stem are true? I was under this impression for some reason. If I'm reading your explanation correctly, you're saying that the answer choice causes doubt on the premise that "It is implausible that hunting by these small bands of humans could have had such an effect."

Second question: Would it be fair to also say that the argument is weakened through this line of reasoning...

"the very few species of North American animals not hunted by the new arrivals from Asia"
(My argument hinges are whether it's ok to assume that since the animals were not hunted by the new arrivals, they POSSIBLY were not exposed to the microorganisms)
And if these animals not hunted were possibly not exposed to the microorganisms and yet still they still died. How could micro-organisms be the "crucial" (i read crucial=necessary) factor that accounts for extinction? Hence the argument is weakened.

Thanks again for your help

[mitchliao]

An additional follow up question.

(E) is incorrect because we don't care whether "some" species of animals (how many? two? three?) became extinct later. We want to explain why the ones in the argument became extinct.

Are we looking to explain why the ones in the argument became extinct... or are we looking to explain why "a factor is crucial(necessary) in why the ones in the argument became extinct"? I may be creating an unnecessary distinction in my head.

Would it be safe to say that in the case of (E), it doesn't weaken the argument because even if the cause - "microorganisms" was present, the fact that there was no effect- there were organisms that did not become extinct within 2000 years, <-- "we know this because it says "some species became extinct more than 2,000 years after the arrival of North America," does not weaken the argument because even though a factor is necessary, it's doesn't need to be sufficient.

Thanks thanks

[giladedelman]

Thanks for the follow-up!

You're right that we need to treat premises as being true. Sometimes, though, strengthen/weaken questions bend this rule a little bit. Here, the premise is not that hunting could not have caused the extinction, but rather that it's "implausible." That just means the speaker finds it hard to believe, which is not exactly the same as stating this as 100% fact.

Regarding your other points, the key thing here is that we're trying to weaken the conclusion that microorganisms were the crucial factor causing the extinctions. (C) weakens it by suggesting that hunting was actually the crucial factor. (E) is irrelevant because the argument is only concerned with the animals that did become extinct. Whether some became extinct later doesn't help us figure out what the cause of the original extinctions was.

Does that help?

[richtailkim]

I also was tripped up because it seems that (C) is attacking a premise, namely, that it is implausible that hunting by these small bands could have had such an effect. I'm a bit unclear as to why that can't be a premise itself.

I'm still puzzled by (A). I understand that you thought (A) actually strengthened the argument by showing how the disease-causing microorganisms would have been even more likely to have been the cause.

But as (A) is stated it seems to provide the possibility of another crucial factor that counts for the extinctions. This is that although the disease played a role in weakening the animals, it really was other predators that brought about the extinctions.

But perhaps this issue hinges on the notion of what makes something a crucial factor, a concept that I do find fairly ambiguous.

- Richard

[LSAT-Chang]

Hey Gilad,
I still don't understand why (D) doesn't weaken it and is "out of scope" like you said above. Here is my thought: since this is a causal argument, we could weaken it by showing that there is the cause but no effect, which (D) does. These humans and animals could have carried the disease with them, but if they don't suffer from them, then we can no longer conclude that it was these diseases that caused the extinction. I am so confused since I thought till now that there are 3 ways to weaken causal arguments:

1. show alternative cause
2. show cause without effect
3. show effect without cause

and I think (D) does number 2. Please please help...

[giladedelman]

Not quite. First of all, we already know that humans and animals did carry these microorganisms over, but they were fine -- it was the animals they encountered in North America that evidently were harmed by them.

(D) would only weaken the argument if the argument were saying that microorganisms always cause the organisms carrying them to suffer from the disease. But that's not what the argument is saying.

Do you understand?

[Joetrot88]

C casts darkness on the conclusion by stating the fact that VERY FEW species that were NOT killed by the people from Asia were extinct.

Think of a groups of animals such as elephants, giraffes, snakes, monkeys, snails and zebras.

Lets assume elephants and giraffes were killed off by the Asians and that the snakes, monkeys, snails and zebras were NOT hunted.

2000 years later out of the snakes, moneys, snails and zebras... ONLY the zebras died off and the rest survived. This shows that VERY FEW species that were NOT hunted became extinct. Or in other words, most of the species that weren't hunted lived.

This is an illustration how this particular answer choice WEAKENS the conclusion.

[taaron]

I still don't understand why D is incorrect. I follow that D establishes that those carrying the microorganisms need not suffer, but by this same logic, those animals in North America that come into contact with the microorganisms may also not suffer as a result! How is this not stating the possibility of cause without effect??

I still find this stronger than C, which may (if indeed more than a coincidence) contradict a premise, but which doesn't weaken the conclusion about microorganisms. It doesn't suggest an alternate cause so much as suggest that maybe hunting is a plausible cause after all, even though the author may have had very good reason for discounting it!

Help would be *very* much appreciated! thank you!!

Not quite. First of all, we already know that humans and animals did carry these microorganisms over, but they were fine -- it was the animals they encountered in North America that evidently were harmed by them.

(D) would only weaken the argument if the argument were saying that microorganisms always cause the organisms carrying them to suffer from the disease. But that's not what the argument is saying.

Do you understand?

[syousif3]

I chose C only after eliminating all the other answers. But i dont understand what it is trying to say. If very few were not hunted became extinct, doesnt that mean they became extinct due to the disease because they were not hunted?

[nthakka]

I chose D as well and got it incorrect when I took this PT.

After reviewing it however, I can identify a good reason why D is incorrect. Even if D is true, does it have to be true that the animal in particular has to suffer from the disease? Couldn't one non suffering deer in a herd of 100 cause the other 99 to suffer? Thus accounting for the extinctions? This would be consistent with the argument, that the microorganisms accounted for the extinctions.

I originally crossed out C because I thought "since it is implausible that hunting could have had such an effect" I thought the author was taking it as given that hunting could not have produced the effect of eradicating animal herds, which is how (C) weakens the argument.

Also, "can" is an important word on (D). This can or cannot happen. We would have to assume that it is happening to be the case. Although with these types of questions this can often be the right answer, because it could end up weakening slightly (1%) when the other answer choices do not. Between C and D however, I can see how C is the better choice with stronger language.

Really have to be cautious with questions like these. It's important to be flexible with the "take premises as given" rule with strengthen/weaken questions, something I have to work on.

[gplaya123]

I would like to explain how C is actually weakens the answer choice.

Let's identify the argument first though.

It says that people from Asia who migrated to North America brought disease with them. Also, it says that there were many species (how many? we don't know) that became "extinct" 2000 years after their migration. Therefore, it's not hunting but disease that killed or caused such extinction.

So, according to the argument, there is two possibilities that cause the extinction: hunting or disease.

Anyway, our job is to however to say either "hey! it's not disease" or "hey! hunting could be an explanation."

The KEY phrase is "very few."

So what C is trying to do is to weaken the idea of argument that the disease was the CRUCIAL FACTOR. If it were a crucial factor, would it have killed only "very few" species? NO! It would have accounted for the majority of extinction. By just mentioning perhaps or 1 or 2 of North American animal killed 2000 years after migration, the answer choice is essentially saying "Hey, if disease was a crucial factor it would not have killed only 1 or 2 species. It would have killed 100 or 200 species," therefore implying that there were other factors or perhaps even hunting now appears to be a plausible cause of extinction.

I hope this helps.

[dukeag]

Hey giladedelman,

I am under the impression that C doesn't really attack the "hunting caused extinction implausible premise," or that we could still take these premises to be true but the conclusion still doesn't follow and C still weakens.

The premise is that it is implausible that hunting by "these small bands" of the FIRST migrations of humans could have caused the extinctions only 2000 years later. But perhaps the flaw in the argument is that it assumes that only these small bands of the first wave of migrants would have hunted these animals, when in fact there were probably many more migrants which eventually came after the first migrations took place. So taken together as a whole big group of migrants, perhaps there were enough humans to cause extinction by hunting.

Am I on the right track?

Thanks for the follow-up!

You're right that we need to treat premises as being true. Sometimes, though, strengthen/weaken questions bend this rule a little bit. Here, the premise is not that hunting could not have caused the extinction, but rather that it's "implausible." That just means the speaker finds it hard to believe, which is not exactly the same as stating this as 100% fact.

Regarding your other points, the key thing here is that we're trying to weaken the conclusion that microorganisms were the crucial factor causing the extinctions. (C) weakens it by suggesting that hunting was actually the crucial factor. (E) is irrelevant because the argument is only concerned with the animals that did become extinct. Whether some became extinct later doesn't help us figure out what the cause of the original extinctions was.

Does that help?

[ganbayou]

Hi,

I'm still not sure why C undermines the conclusion..
If the answer says "Most of species" instead of "very few species (means almost none)" then I can understand why C undermines...
So those species which were not hunted lived for 2000 years, but those were hunted went extinct, and this can be the reason hunting was the cause of the extinction.
Why "Very few species" can undermine here? I thought it's the opposite and actually strengthen the conclusion by eliminating alternative explanation.

Thank you

[rinagoldfield]

Hi Ganbayou,
If “very few” non-hunted animals became extinct, that means most non-hunted did NOT become extinct. Thus, (C) posits a correlation between hunting and extinction, and between non-hunting and non-extinction.
Hope that helps.
--Rina

[mshinners]

I also was tripped up because it seems that (C) is attacking a premise, namely, that it is implausible that hunting by these small bands could have had such an effect. I'm a bit unclear as to why that can't be a premise itself.

The word "implausible" doesn't mean "impossible" or even "unconvinving." The word "implausible" means that the speaker doesn't mean something is reasonable.

So the premise in question here is, "The essaying finds it implausible that hunting could cause extinction."

(C) doesn't call that into question - it's still a fact that the essayist views it as implausible that hunting caused extinction. However, (C) gives us evidence that it did actually happen, so while the essayist might still view it as implausible, it's looking like he's wrong.

This is a common high-level trick the LSAT uses - we can't call premises into question, but some premises tell us what people think. If we call their belief into question, we're not questioning the premise; instead, we're questioning the basis for their belief.

To come at it from another angle, if I was going to contradict this premise, I would need to say, "The essayist doesn't actually believe it to be implausible that the hunting caused extinction."

[mshinners]

1. show alternative cause
2. show cause without effect
3. show effect without cause

and I think (D) does number 2. Please please help...

That is absolutely correct, until you apply it to answer choice (D)!

What's the causal relationship here?
Cause - Microorganisms
Effect - Extinction

(D) says that we have INDIVIDUAL humans/animals that carry the disease without dying. So we have the Cause, definitely. But our effect was extinction. The survival of INDIVIDUAL members of a species doesn't amount to enough information to say that we don't have the effect (and, in fact, we know that the effect happened here, as there are extinct animals).

[dhlim3]

Quick Question.

If C had instead used "some" instead of "very few", would that have turned the answer choice into a strengthener?

Also, in LSAT, is there a distinction between "some", "few", "very few", "small number", and such? When I first came across C, I considered "very few" as interchangeable as "some", and crossed it out.

[contropositive]

Quick Question.

If C had instead used "some" instead of "very few", would that have turned the answer choice into a strengthener?

Also, in LSAT, is there a distinction between "some", "few", "very few", "small number", and such? When I first came across C, I considered "very few" as interchangeable as "some", and crossed it out.

I had the same reasoning for eliminating C. I was taught that "very few" is interchangeable for "some" and that is why I eliminated C. I actually had the same reason for eliminating the right answer on question 22 as well.

After careful review of both questions, I realized its better to think of "very few" as just "very few" instead of "some" because that makes you think it could be "all" since "some" is one to all.
For example, if we say "very few species that were not hunted became extinct" then that means "most of the species that were not hunted did not become extinct" which implies that perhaps IT IS the hunting that is the cause of extinction. Otherwise, how come the "most of the not hunted survived?" this is how C is casting doubt on question 21.

Same thing on question 22. This question asks to strengthen and there was a sampling error. It was assuming that the Plant B did not receive nutritious breakfast elsewhere and the correct answer is saying very few Plant B ate nutritious breakfast which means most did not. thereby, strengthening the assumption in the argument (you can refer to the appropriate forum for more discussion on this question).