#10 - Insects can see ultraviolet light and are known to

[moshei24]

Is this stimulus saying that because they identify important food sources and mating sites by sensing the patterns that that would imply that when insects are attracted to Glomosus spiderwebs, it's for that reason and no other reason? So the stimulus is assuming that there isn't any other other reason for the insects to be attracted to these webs? Though, one could object and say that they're attracted to the webs because they could see the webs, and it has nothing to do with ultraviolet light?

And that's why (E) is correct, because it gives a two cases where they would see the web, and they go to the web with the ultraviolet light? And the point of the white light being mentioned is to let us know that they could see the webs? If the white light wasn't there, one could argue that in this case they went to the ultraviolet light one because the other one wasn't visible to them at all. Yet, in the stimulus, it says that they are attracted to the webs because of the ultraviolet, yet if we don't have a case where they go to the ultraviolet light instead of the clearly visible web without it, the argument would be weak? But in the answer (E), why couldn't the reason they went to the ultraviolet one be because it had two things that attracted them? Both the web itself and the ultraviolet light. Or even though that could be a counter to (E) strengthening it, it still does strengthen it; though, not without there being a possibility for one to argue back?

Sorry about the long rant there. Can you clear it up for me, please?

Thanks!

[Steve Stein]

Hey Moshe,

That's right--because insects like UV light, and they also like this particular type of web, the author concludes that it must be the UV light reflected in the web.

The stimulus is followed by a Strengthen question, and the correct answer choice compares a web with UV light to one without a UV light and shows a preference for the one with the UV. That strengthens the author's case that it's the UV that the insects find appealing.

I hope that's helpful!

~Steve

[MikeJones]

Hey Moshe,

That's right--because insects like UV light, and they also like this particular type of web, the author concludes that it must be the UV light reflected in the web.

The stimulus is followed by a Strengthen question, and the correct answer choice compares a web with UV light to one without a UV light and shows a preference for the one with the UV. That strengthens the author's case that it's the UV that the insects find appealing.

I hope that's helpful!

~Steve

Hey Steve,

Might you be able to explain this flaw type a little bit deeper? The most obvious seemed to be that the author is assuming that since one thing is a possible cause, that there aren't any other causes. But I feel like there's something I'm missing, like there might be multiple flaws. I can't eliminate the prospect of there being some sort of part to whole/whole to part flaw here.

[James Finch]

Hi Mike,

Do you mind elaborating on the flaw type you asked about? In reading the stimulus, I don't see a flaw present, nor one in Steve's response.

Thanks!

[MikeJones]

Hi Mike,

Do you mind elaborating on the flaw type you asked about? In reading the stimulus, I don't see a flaw present, nor one in Steve's response.

Thanks!

Wouldn't there have to be a flaw or an assumption for this to be a strengthen question?

In any case, the argument seems to be presuming that since insects can see UV and are attracted to things that reflect UV, that the insects are attracted to this web because of UV and not because of something else. Answer E seems to confirm this by saying that they are attracted to the web with the UV and not the other, which might possess another attractive characteristic unrelated to UV.

[James Finch]

Hi Mike,

The way the LSAT is written takes these uncertainties into account, unless its a flaw question. In this case, the scope of the conclusion is that the insects are "probably" attracted to the webs because of their reflection of UV light. And you are correct that this does leave open the possibility of an alternate cause, perhaps one that causes both the insect attraction and the reflection of UV light. That's exactly the sort of thinking that makes for good prephrasing on weaken/strengthen/flaw questions when the stimulus involves causal reasoning.

Here (E) is the only answer that helps make the conclusion more likely to be true, by presenting evidence that helps isolate the UV light as the source of attraction for the flies.

[ameliakate]

Hello,

I selected answer choice D for this question. The author stated, “Thus, insects are probably attracted to these webs because of the specific patterns of ultraviolet light that these webs reflect.” I took this to mean that it was not only the presence of ultraviolet light the insects were attracted to, but the pattern the ultraviolet light emitted. Hence, I selected D.

Would someone mind explaining why E is correct?

[Jeremy Press]

Hi Amelia,

The answer choices to this question are very tricky, so keeping them separate is key.

Let's start with answer choice D. If it were true that we experimented on two webs, a Glomosus web and a "synthetic web of similar pattern that also reflected ultraviolet light," and we wanted to strengthen the conclusion that UV patterns in webs attract insects, then what we would need to know is that insects were about equally attracted to the Glomosus web and the "similar pattern" in the synthetic web. If we knew that, it would show that the two webs with similar UV patterns were having about the same attractive effects on the insects (then it's more likely to be the UV that's doing the attractive work!). Unfortunately, all answer choice D tells us is that many fruit flies flew to the Glomosus web. That doesn't tell me as much as I'd like to know. "Many" is too vague numerically (similar to the term "some"). I really need to know whether approximately the same number of fruit flies also flew to the synthetic web. So answer choice D is indefinite in its effect on the conclusion.

The reason answer choice E is correct is because, to strengthen a causal relationship (here, the relationship between UV patterns and insect attraction), we expect to find other circumstances where both the cause and the effect are present: E gives us that, because it gives us a Glomosus web with a UV component to the light (the cause) and it gives us the majority of insects being attracted to that web (the effect). It's even more powerful than that, because to strengthen a causal relationship, it's also helpful to show in the absence of the cause (in E, the Glomosus web without a UV component), the effect is also not occurring (i.e., not as many fruit flies are being attracted to that web).

I hope this helps!

Jeremy

[silent7706]

Hello,

The conclusion emphasizes on "specific patterns of UV these webs reflect", while (E) focuses on with and without UV. I a see gap here, but I tolerated (E) because question stem says "most strongly supports". I feel that (E) provides a strong evidence to whether insects are attracted to these webs because of UV light reflection, but does it also support the claim that insects are attracted to specific patterns of UV light of these webs?

Thanks in advance.

[Adam Tyson]

Like you, silent7706, I was looking for something to support the "specific pattern" aspect of this argument, but E ultimately was the only one that helped at all. Since this is a Strengthen question, rather than a Justify the Conclusion question, a little help is all we need.

Answer D is intended to be the attractive wrong answer here, because students might think the fact that "many" flies flew to one of the webs is an indication that it had to do with the "specific pattern" of the light reflected off of that web. Of course, that answer doesn't tell us whether the two webs had different "specific patterns" or not, and in fact it clouds that issue by saying that the webs had "similar patterns". Also, "many" doesn't mean "all", so many others could have flown to the synthetic web.

Answer E tells us nothing about specific patterns, but at least it tells us that ultraviolet light appears to make the web more attractive, and that helps, if only a little.