Q24

[zhangstagangsta]

For this question, I chose C by POE. However, the "only if" is bothering me because I think it's too strong. How do we know that the author does not feel that there are no alternatives to insecticides and natural predators?

[aileenann]

It's great that you worked by POE - that is generally how you want to approach an RC question unless there is a clear correct answer. Here, I agree that (c) could scare one off because of the "only if." However, let's see what we can find to support this inference from the passage.

I think there are a few parts of the text that could support an "only if" inference, though not as tightly as we might like to see on the LSAT.

Consider the first sentence of the passage, "Sometimes there is no more effective means of controlling an agricultural pest than giving free rein to its natural predators." In addition to providing background, that sentence is arguably favoring natural remedies over artificial ones.

Also consider the first sentence of the last paragraph, "Applying parathion in this instance is a clear case in which using a pesticide would do far more harm than good to an agricultural enterprise."

I don't know that we know anything about what the author feels about besides pesticides and natural remedies (i.e. if there is a third alternative), but we do know the author seems to strongly favor natural remedies over artificial pesticides. For that reason, we can probably conclude the author would only use a pesticide if there were no natural remedy. While (c) is not air tight, it is the best response.

Great implementation of POE, and good question. Let me know if you have any follow-up questions or comments. Thanks!

[rishisb]

Hello ATLAS,

I am wondering if you could please explain why answer choice B is not the best answer choice? I selected this because I thought that it implied that we should be careful not to harm helpful natural-predators, such as the one described in the passage. After all, the author said that some pesticides hurt the good guys, and that we should be careful use pesticides on strawberry plants. So, by parity of reason, I thought that we should, too, be careful about releasing predators that might hurt the good, natural-predators.

Thank you!

[aileenann]

Thanks for the followup question!


I think (B) is a little bit more specific than you phrased it. In particular, there is a timing element - this is not about not using pesticides but rather about not using them until we understand them. I don't think there is any support in the passage for that.

Secondly, and perhaps more importantly, I don't see any support in the passage for the idea of cautioning against the natural predators - the author was really concerned about the pesticides, as you said. I think you're bringing in an outside assumption or two if you think they can be connected up in the way that would justify (C).

Does this make sense? Please let me know if you have follow-up questions or concerns!

[rishisb]

Hello, Aileenann:

Thank you for your help. I really appreciate it!

Anyways, I was thinking about answer choice C, the correct answer choice. I'm wondering if the reason answer C is more correct than choice B is that C's "only if" statement can be translated into:

If pesticides should be used to control pest populations, then, the use of natural predicators has proven ineffective.


Now, we know that this if-statement is the same as its contrapositive , i.e.: If the use of natural predators has proven effective, then, pesticides should not be used to control pest populations.

And, this contrapositive sounds like something the author would agree to.

Q: Do the LSAT folks really test formal-logic statements like this in RC section? (If so, I better be on alert for conditional statements that are answers choices in the RC section, too).

[aileenann]

Thanks for your follow-up.

First, the short answer is that YES - conditional logic is fair game even on the RC section. You should never be off your guard on the LSAT. Never think to yourself "that would be too hard, they wouldn't do that" because they would and they will

Secondly, your rephrase is dead on, and it was a great idea to use this to put the answer choice into a form you could feel more comfortable with. Just as the LSAT may test you on conditional logic even in RC, you should feel totally free to use conditional logic wherever it will make your life easier or at least give you a different way of looking at the problem.

[chunsunb]

Hi.

I really don''t like (C) because I can't find any support for it.

"Sometimes there is no more effective means of controlling an agricultural pest than giving free rein to its natural predators." -->> this statement is compatible with the statement that in other times, other means ( such as pesticides) are more effective than natural predators.

"Applying parathion in this instance is a clear case in which using a pesticide would do far more harm than good to an agricultural enterprise."-->>if anything, this sentence seems to limit the scope of the result to this case only; i.e. We found out that in the case of typhlodromus and cyclamen mites, natural predators were more effective than the pesticide -- but we are not sure about other plants / pesticides.

Nowhere can I find the claim that people should first try to seek natural predators and that pesticides shouldn't be used unless it is found out that natural predators are ineffective.

FOR INSTANCE: we found out that in question 23, pesticide X has the same effect as the use if Typhlodromus. Who is to say that the author would suggest using Typhlodromus instead of using pesticide X? In the passage, the author seems to endorse Typhlodromus instead of parathions simply because parathions were ineffective


Thanks for ur help!!!!!!

[ottoman]

I felt that A is very similar to C.

I chose C on my first attempt and switched to A when I reviewed the section.

Can someone help me understand the reason C is better than A?

Thank you!

[christine.defenbaugh]

Thanks for posting, ottoman!

There are two primary issues with (A) that toss it right off the bridge.

First, the author never suggests that parathion should be used for anything. The experiments all show situations where parathion was bad. Specifically, the parathion "does not affect the cyclamen mite", so the author would never advocate using it to control cyclamen mites!

In fact, the author never implies anything about what one should do if the predator mites fail. The entire passage is about how AWESOME the predator mites are, and how much more awesome they are than pesticides. And this highlights the fundamental difference between (A) and (C) is which way the conditional logic points. Notice that (C) uses the key phrase "only if" - that phrase introduces the necessary condition.

Let's say we changed "parathion" in (A) to just a generic "pesticides". If we gave a shorthand to both (A) and (C), they would look like this:

(A): If predators fail, then use pesticides.
(C): If predators DO NOT fail, then DON'T use pesticides.

While these appear similar at first glance, they are actually negations of each other! Our author never even hinted at what one should do if the predators fail. But since he favors the predators so much, it is entirely reasonable that he would agree that if the predators WORK, keep the pesticides in the can!

Watch out for details like "parathion" (which would kill the predators, not the cyclamen) and don't forget that "only if" is not the same thing as "if"!

Does that help clear things up a bit?

[Athomas87]

Hey guys, this is my first time posting in the forum

Based on earlier explanations, I understand why C is the correct answer but in order to get better at eliminating wrong answers, why is E wrong?

[daijob]

Hi,
So just want to double check...E is incorrect because although the part talking about "more effectively" is OK, the passage does not suggest it does not harm the crops?

Thanks,

[ohthatpatrick]

Do you have a line reference to support the idea that predators are usually more effective than pesticides?

The first line of the passage seems close to being on that topic, but it says, "Sometimes there is no more effective means of controlling an agricultural pest than giving free rein to its natural predators."

Sometimes, predators are the best or tied for the best.

We have no evidence they're ever BETTER, although this sentence leaves room for that possibility. We only have evidence that SOMETIMES they're AT LEAST AS good.

The last paragraph does sound like a case when predators are BETTER than pesticide at controlling pest populations.

But (E) says "generally", which means in 51% or more of cases. We can't justify that sort of statement.

In addition, as you noted, I don't think we ever discuss whether or not predators harm crops.

== other answers not yet discussed ==

(B) This is pretty opposite of the whole passage. The author is discussing the predator option for strawberries as a "case in point" in which using predators to control seems wise.

(D) This is the flipside of (C), basically. "All other things being equal, prefer PESTICIDES to PREDATORS."

The author does not say anything like this and seems to implicitly feel the opposite way.

[JohnZ880]

This is a type of RC question that really bugs me. In my reading, the passage almost suggests the opposite of C. It doesn't suggest that natural predators should always be used if adequate. Rather, the author frames the debate between pesticides and natural predators as one of relative effectiveness, not basic satisfaction.

Line 1: "Sometimes there is no more EFFECTIVE means of controlling an agricultural pest than..."
Paragraph 2: Literally all about how Typhlodromus is an effective predator that both kills the prey population without damaging the crop
Line 50: "Applying parathion IN THIS INSTANCE is a clear case in which using a pesticide would do far more harm than good to an agricultural enterprise"
This is a very, very narrow claim. Why is it better? Because Parathion kills the predators and doesn't kill the cyclamen mites, whereas Typhlodromus kills the prey and doesn't damage the crops. Thus, Typhlodromus is more effective and should be favored.

The author's point seems to be rather simple. If you imagine he/she in a conversation, he/she would probably say something like, "hey farmers, don't just assume that pesticides are better. In fact, sometimes pesticides are counterproductive in that they kill natural predators, while doing little damage to the actual prey population."

The basic inference I would draw from the above line of reasoning is that in the event that natural predators are not more effective than natural predators, pesticides should be used. Relative effectiveness still absolutely allows for the scenario in which natural predators may be adequate (C), but not necessarily more effective.

Where am I going wrong here?

[JosephC975]

This is a "most likely to agree with" question. All of the other options are much more flawed than C.

That's really the answer to the OP's question as well -- the _only_ way to proceed on this type of question is to eliminate all the 'worse' answers. The author could be fairly likely to agree with an answer, but that answer still be long, if another answer poses something he is more likely to agree with. Similarly, the author doesn't need to be particularly likely to agree with an answer for it to be right -- as long as it's the choice that he's _most_ likely to agree with.