Q5 - During its caterpillar stage

[mshinners]

Question Type:
Necessary Assumption

Stimulus Breakdown:
When it's a caterpillar, this moth eats a plant that make it toxic/taste bad. This plant is endangered. Therefore, the moth is, too.

Answer Anticipation:
This argument is the classic example of a False Choice flaw. Since the argument hasn't established that this plant is the only thing making the moth toxic, we can't assume that it going extinct would lead to problems for the moth. An answer could deal with this gap ("The Natal grass cycad is the only thing that allows the moth to taste bad.")

There's another False Choice flaw - there could be factors other than it's bad taste to keep it alive even in the face of increased predation. While the bad taste is one factor allowing it to survive, there could be other. An answer could just as easily deal with this flaw ("The leopard magpie moth can survive even if predators start eating it at a heightened rate.")

Correct answer:
(A)

Answer choice analysis:
(A) Boom. This answer choice deals with our first gap, as stated above. If we negate it—other things besides the grass make the moth taste bad—the argument falls apart because the grass going extinct wouldn't necessarily impact the moth. This answer continues the recent pattern of stronger-worded Necessary Assumption correct answers.

(B) Degree/scope. Since the argument is talking extinction, it's too much to say that it lacks the speed/agility to escape from ANY POTENTIAL predators. That's way too broad since it includes animals that may not even currently be eating them.

(C) If anything, opposite. An inability on the part of predators to even know that they taste bad before eating them suggests the bad taste doesn't have much to do with their survival. Eaten and swallowed or eaten up and spit out is just as dead.

(D) Out of scope. The danger to the moths, according to the argument, comes from the endangered status and possible extinction. If we negate this—the moths can locate the grass even if it's rare—the argument can still work because the grass could still go extinct.

(E) Degree. Even if some predators have developed a tolerance, it could be at a level lower than that needed to drive them to extinction.

Takeaway/Pattern:
Negation test! Also, recent tests have been including Necessary Assumption answers that are both correct and strong. Remember: The correct answer can be as strong as the argument/conclusion, and this is a pretty strong conclusion ("is"; "extinction").

#officialexplanation

[b.lin.22.13]

I'm still having trouble seeing why B is incorrect. When using the negation test, the answer choice says "the leopard magpie moth HAS the speed or agility to escape from any of its potential predators." Doesn't that destroy the argument by saying it doesn't matter whether or not the moth is in danger of extinction from predators?

[andrewgong01]

I'm still having trouble seeing why B is incorrect. When using the negation test, the answer choice says "the leopard magpie moth HAS the speed or agility to escape from any of its potential predators." Doesn't that destroy the argument by saying it doesn't matter whether or not the moth is in danger of extinction from predators?

b.lin.22.13, that's what i thought to during review even though I was convinced with A through the negation test. But , notice that the question said eating the grass applies in the caterpillar stage (not the moth stage). Therefore, it does not matter wether or not when the subject becomes a moth has or does not have the ability to fly and escape. Why? Because the argument is talking about extinction of the species because the grass is going extinct but the grass matters for the caterpillar stage and not the moth stage.

Put differently, this is how we could see the argument to disprove "B":
We can say that moths do have the ability to escape. But, how does one become a moth? One starts as a caterpillar first. But how do we ensure the subject is able to live on and offer protection when the subject becomes a moth from a caterpillar? Consume macrozamin. But how do we get macrozamin? Eat the grass, which is going extinct. Hence if the grass is going extinct, caterpillars (i.e. 'babies') are not going to get the necessary toxins needed for them to carry on living when they eventually become a moth. Hence, it does not matter if moths can or can not escape because without the grass, these subjects would not even be alive as moths and may have died in their caterpillar stages.

It seems like the detail of "during its caterpillar stage" seems to have played a pretty big role and not random filler like questions

Choice A is unaffected by this nuance in catepillar vs moth because it just says these moths will lack getting macrozamin and it could be the case that the benefits of macrozamin only get realized after you become a moth from a caterpillar (e.g. analogy: you learn some things in elementary school that is "useless" then but later on in life you use the benefits of it - such as writing in cursive.) ; however, it really should not matter because it is not directly saying at a certain stage; rather it is just saying in general

Not sure if this is a valid way but what are your thoughts on this approach?


"(B) Degree/scope. Since the argument is talking extinction, it's too much to say that it lacks the speed/agility to escape from ANY POTENTIAL predators. That's way too broad since it includes animals that may not even currently be eating them" ----> I think this is what you were getting at though?

[jambam]

Distinguishing the correctness of A from B seems somewhat arbitrary. I don't see either as necessary to ensure the validity of the argument and the extant either weakens the argument when negated depends on certain assumptions of questionable appropriateness.

B is incorrect with the assumption that, if true, magpie moths would successfully utilize their speed and agility to escape potential predators infrequently enough that they will still be in danger of extinction.

Yet A could also be incorrect with the assumption that, if true, the means other than eating the Natal grass cyad by which magpie moths can make themselves highly unpalatable to predators are so difficult to obtain that these moths will still be in danger of extinction.

How should we determine the assumption LSAC deems more reasonable?

[YaW238]

isn't answer A also a sufficient assumption for the argument? Sometimes I tend to not choose a sufficient assumption answer when the question stem asks for necessary assumption.
Thank you!

[MeganG1]

So, this was the only question I got wrong in this section, and now I am just facepalming.

Ok, so B is wrong because:
When you negate it, the choice says - The leopard magpie moth DOES have the SPEED OR ABILITY to escape from any of its predators. Ok, well, does that ruin the argument? Nope! Being not fast enough does not guarantee extinction. What if the moth sleeps, and is not using the speed? What is the moth is a baby caterpillar? Way too broad of an answer.

A is correct because when you negate it, it rules out the grass as being the only option, and thereby weakens the argument. You need the grass to be the only way to fend off predators because if there was another way, we would have no ~good~ argument.

[ZaftigG65]

Choice A is correct because the argument is about not being able to make itself unpalatable = extinction. And being that it cannot do it the cycad way, it will become extinct. Choice A fills in the gap that the cycad way is the ONLY way. Whereas B is unnecessary. Maybe they have the agility, maybe they don't. The point is, not having unpalatableness will lead to extinction. (Perhaps they won't utilize their speed and agility). Another more glaring issue is the strong term "Any" in the choice. We definitely don't need them to be able to escape from ALL their predators. Even some would have sufficed especially if those some are the main predators.