Q1 - The painted spider spins webs

[griffin.811]

Couldn't A be plausible as well (I did go with D, just trying to figure out the wrong answers)?

Core:

P spider more successful than its competitors because It spins a stickier web, and stickier webs are more efficient at trapping prey that FLY into them and spiders prey on insects trapped in their webs.

A introduces the possibility that perhaps the P spider is better at catching flying insects, but what if it is way worse than the other spiders at catching crawling insects, and crawling insects make up the majority of the insects in a habitat.

The fact that spiders can also prey on non flying insects isn't excluded by any of the premises, nor does it seem far-fetched.

Thanks

[bixbee]

I've been lurking on the forums for a month or two now, but this is my first post!

I'm having the same trouble as the previous poster in determining why (A) is incorrect. I narrowed it down to (A) and (D), but decided against (D) because I reasoned that the fact that stickier webs are more visible to insects than are less-sticky webs doesn't necessarily mean insects are less likely to fly into them. What if the insects can see the webs but don't register them as a threat and fly into them anyway? To me, it seemed like (D) would require making my own additional assumption above and beyond the given information that "greater visibility=insects less likely to fly into."

While (A) certainly would've been a stronger choice if it had said something like "MANY of the species of insects living in the painted spider's habitat are NOT flying insects," I don't see why "Not all of the species of insects living in the painted spider's habitat are flying insects" is incorrect.

Even if "not all" meant that only one species of insect in the painted spider's habitat was not a flying insect, what if that one species made up 75% of the total insect population in the painted spider's habitat? Wouldn't that weaken the argument that the painted spider is a more successful predator than its competitors?

[kramer_cj1]

I'm going to try to take a crack at this, although I'm not 100% on this. I missed this question and attempting to review why I may have missed it.

The stimulus presented states that this species of spider has a web that is "much sticker" than other species.

I would agree that A and D are quite tricky and I too narrowed them down as contenders.

As with most weaken type questions, this stimulus has a cause effect relationship. I think I diagrammed the question correctly. Would look something like this:

C/ sticky webs. E/ better success rate.

The reason I chose A was because I thought I could reverse an assumption: that is, not all prey are flying animals. After reviewing I though, we'll geez... If there not flying, what are they...... The only thing I could come up with is the logical opposite of flying: not flying, or what would equate to ...... Walking. Therefore I that sense, A doesn't really weaken the causal relationship and d wins by default.

In short, I could see that D weakens the causal relationship, by showing that even though the cause has occurred, the effect may not always happen.

Hope that helps.... Makes sense.

[ohthatpatrick]

I can see why there's some hesitation about (A) vs. (D).

It essentially boils down to the often-frustrating part of dealing with Strengthen/Weaken answers: the correct answer rarely EXPLICITLY says something that strengthens or weakens. We have to connect the answer to the argument core using conservative amounts of common sense.

If you look above this question (at the beginning of every LR section) it says that we shouldn't make assumptions that are "implausible, superfluous, or incompatible" with the stimulus.

Weaken

Prem:
Painted spider's webs are stickier than its competitors'
+
Stickier web = more efficient at trapping insects that fly in
+
Spiders prey on insects by trapping them in their webs

Conc:
Painted spider is a better predator than its competitors

(A) Note: "not all A are B" translates into "some A are ~B", so this answer says, in friendlier terms, "Some insects in the painted spider's habitat are NOT flying insects".

The rationale for how (A) would weaken goes something like this: "Oh, well, then even though the painted spider would win the FLYING insect category, its competitors might win the non-flying insect category."

Keep it.

(B) This strengthens.

(C) The venom doesn't kill right away but it paralyzes right away, so the insect likely still dies a slow death (hence, this isn't much of a knock against the painted spider's predation skills). More importantly, this answer makes no comparison to the painted spider's competitors, so for all we know they have the same type of venom.

(D) The rationale for (D) is that if a web is more visible to prey than it's more avoidable. So this presents a downside of the stickier webs. The argument, naturally, only mentioned an advantage of stickier webs. Importantly, this disadvantage keeps an insect from ever entering the web, so this disadvantage could be way more important than the advantage sticky webs have IF an insect enters the web. Keep it.

(E) Does not weaken. Potentially, the painted spider's webs are as large as its competitors', so this doesn't point to an advantage for either side.

So ... down to (A) vs. (D), we have to ask ourselves which story involves more conservative common sense / which idea is stronger / which idea relates more to the core

(A)'s story is "if there are non-flying insects in this habitat, then the competitors are better at preying on them + the non-flying insects comprise a bigger portion of the spiders' diet than the flying spiders".

(D)'s story is "if an insect can see a web, it might try to avoid it".

(D) wins.

(A)'s assumptions are what we could call "superfluous" ... what reason do we have to assume that the competitors have an advantage when it comes to non-flying insects? what reason do we have to assume that non-flying insects are a more substantial part of the spiders' diets? "SOME non-flying insects" just means "at least one".

One final note: there is a premise that says "Spiders prey on insects by trapping them in their webs". It's hard to say whether to interpret that as "ONLY by trapping them in their webs", but that kind of generalization sounds like it's defining THE way spiders prey on insects.

So who cares whether an insect flies into or walks into a web? The stickier web would trap them better either way.

Hope this helps.

[WaltGrace1983]

Couldn't we just eliminate (A) because the conclusion deals with a comparison and (A) does not?

[coco.wu1993]

I think A would a good answer if it says "not all of the species of insects the painted spider prey on are flying insects." Any thought?

[ohthatpatrick]

I like Walt's instinct that the correct answer will probably be comparative in nature, since the conclusion we're trying to weaken is comparative.

But I wouldn't say we can be SO insistent on a comparative answer choice that we can summarily eliminate any non-comparative idea.

It's always possible to weaken an argument by simply undermining the trustworthiness of its evidence ... such a possible attack strategy would have no direct bearing on the conclusion, so it wouldn't matter what type of claim the conclusion is.

Basically, good instinct, but remain flexible.

The tweak of re-writing (A) to say "not all the insects the painted spider preys on are flying" is an improvement, but it still wouldn't beat (D) and it still wouldn't really weaken the argument.

Re-written (A) would be saying "some of the insects that the painted spider preys on do not fly". Does that undermine any claim in the evidence? Did the evidence say or need to assume that ALL of the painted spider's prey are flying? Does it undermine the truth of the conclusion? It doesn't seem to me to do either.

EVIDENCE:
We would still know that the painted spider has the stickiest web, which means its web is the most effective at trapping insects that get in their web. If, as re-written (A) would say, the painted spider preys on some non-flying insects, how would they get into the web? The short answer is it's not our concern. Maybe they fall into the web. Maybe they walk into the web. If the non-flying insects never enter the painted spider's web, then it's untrue to say that the painted spider actually preys on them, so it's not like we suddenly have an objection like, "But wait! How can it be the most successful predator when it can't manage to trap non-flying insects".

CONCLUSION:
Re-written (A) doesn't introduce any consideration that makes us think some OTHER predator is more successful than the painted spider.

Again, remember the puny, almost inconsequential strength of "not all". It can basically mean that 99% of the insects the painted spider preys on are flying, and 1% are not. Big whoop.

Let me know if I'm missing a different way to make a possible counterargument with the re-write of (A), but I think the two big takeaways making it irrelevant are:
1. "not all" has almost no punch at all
2. this doesn't in any way affect our comparative conclusion without us leaping to a lot of unfounded assumptions about the superiority of other predators to capture non-flying insects.

[coco.wu1993]

I still don't get why A is wrong.

The core:
Premise: The painted spider spins stickier webs. + Sticker webs are more efficient at trapping insects flying into them.
Conclusion: The painted spider is a better predator.

I think the assumptions here are 1) not all preys are flying insects; 2) not all flying insects will be flying into the web. D attacks the second assumption.

However, I think A attacks the first assumption as well. It does not weaken the conclusion since we are uncertain about whether stickier webs are more efficient at trapping non-flying webs. But it successfully attacks the reasoning of the argument. We cannot just conclude that the painted spider is a better predator from the fact that they are better at preying flying insects. What if most of the prey cannot fly?

Can anyone please help? Thanks in advance!

[ohthatpatrick]

Be careful. In interpreting (A) you're saying things like "well what if MOST of the painted spider's PREY are non-flying?"

I agree that would potentially weaken, but where did you get that notion?

(A) only says that SOME of the insects that LIVE in the painted spider's HABITAT are non-flying.

Those two are worlds apart in strength and relevance.

The argument says:
b/c the painted spider's stickier web is more efficient at trapping flying insects that fly into them, the painted spider is a more successful predator.

We are definitely assuming that at least some insects fly into these sticky webs, otherwise their extra stickiness would confer no advantage.

We do NOT have to assume that ALL the insects that live in the habitat are flying insects. We only have to assume that AT LEAST SOME of the insects in the painted spider's habitat are flying insects.

So (A) doesn't attack that assumption.

(D), meanwhile, DOES attack the assumption that AT LEAST some insects fly into the painted spider's web.

Hope this helps.

[jmlopiano]

I'm confused. Regardless, doesn't (D) still require the assumption that insects avoid webs that reflect light, and thus, more visible webs? Common knowledge I feel allows that some flying insects are attracted to sources of light. These spiders might hunt at night bathed in the full moon for all we know. All their food may be moths. I realize that's another whole level I'd have to assume to come to the conclusion that the flying insects in the habitat of these spiders are attracted to the webs that reflect light, but isn't it also a deep assumption that (1) webs that reflect light deter insects from being trapped in them, and, (2) that my hypothetical isn't the case here, but this other hypothetical (a habitat of insects that avoid reflective webs) is the case? Either way, it seems (D) requires a set of assumptions as well. (A) on the other hand merely states that some of the insects do not fly. That only requires thinking about how the passage specifically states that the webs are better at catching insects that fly into them. I know (D) is right anyway, but how do we gauge at what level diving is diving too deep. For me, (D) attacks nothing. It just says that these webs are more reflective of light than other webs, and thus more visible. How does a test taker know that this equals something that works against the spider webs?