#8 - Most plants have developed chemical defenses against

[Administrator]

Complete Question Explanation

Weaken Except. The correct answer choice is (E)

The argument in this stimulus is fairly straightforward, though clearly flawed:

• Premise: Natural pesticides aren’t harmful.
  Conclusion: Thus the additional threat from synthetic pesticides is minimal.

This reasoning is weak, because it neglects the potential dissimilarities between natural and synthetic
pesticides. Since this is an Except question, we should eliminate the four choices that do weaken the
argument, in search of the single answer choice that does not weaken the argument.

Answer choice (A): This response weakens the argument; by pointing out that humans have had a long
time to get used to natural pesticides, the author strengthens the contrast between natural and synthetic
pesticides.
Answer choice (B): This response points out that spraying with synthetic pesticides leads to higher
relative concentrations, which makes it more likely that spraying with synthetics could be dangerous.
This response weakens the argument, and is incorrect.

Answer choice (C): If synthetic pesticides have a more highly concentrated toxicity, they might be more
dangerous, so this is another response which weakens the argument.

Answer choice (D): If synthetic pesticides affect a wider variety of species, this would increase the
likelihood that humans might be affected, so this choice weakens the author’s argument.

Answer choice (E): This is the correct answer choice. If the synthetic pesticides are similar in
chemical structure to the natural pesticides, that would strengthen the claim that we might expect the
same degree of harmlessness in synthetic pesticides as in their natural counterparts. This response does
not weaken the argument and is therefore correct.

[Dazhiw]

Hi there,

I could understand that the correct under E strengthen the argument, but I can't understand why answer A weakens the argument. My view is that the adaptation to natural plant pesticides of humans has nothing to do with the threat from synthetic pesticides. It's more like supporting that humans ingest these natural pesticides without harm every day.

thank you.

[Steve Stein]

Hi,

The author's claim is that synthetic pesticides will pose a minimal threat to people, based on the fact that people ingest natural pesticides.

But if, as Answer Choice (A) provides, people have had plenty of time to adapt to natural pesticides, that provides a distinction between natural and synthetic pesticides--if people have not yet adapted to synthetics, the threat could be a lot greater than "minimal."

I hope that's helpful! Please let me know whether this is clear--thanks!

~Steve

[Dazhiw]

Hi,

The author's claim is that synthetic pesticides will pose a minimal threat to people, based on the fact that people ingest natural pesticides.

But if, as Answer Choice (A) provides, people have had plenty of time to adapt to natural pesticides, that provides a distinction between natural and synthetic pesticides--if people have not yet adapted to synthetics, the threat could be a lot greater than "minimal."

I hope that's helpful! Please let me know whether this is clear--thanks!

~Steve

Hi Steve,

Thank you for the explanation, it make some sense to me, but how do you know from the from answer A or the passage that "people have and plenty of time to adapt to natural pesticides" automatically means that the threat is greater than "minimal" before the adaptation of natural pesticides? neither answer A nor the passage said that before people adapt to natural ones, the natural ones have greater threat than "minimal". so, the assumption of "before adapt to synthetic ones, the threat could be a lot greater" is not supported by the passage, at most, it might be supported by the common sense outside of this passage.

Thank you.

[Steve Stein]

Hi,

Thanks for your response. Let's start at the beginning. The author's argument is basically this:
Many natural pesticides aren't harmful to humans, so synthetic pesticides must not be much of a threat (the idea is that the two types of pesticides are so similar that if one is harmless, so is the other). Answer choice (A) provides that people have had thousands of years to adapt to natural pesticides--maybe it's that adaptation that makes natural pesticides harmless. If that's the case, then maybe synthetics could still be a threat, since we haven't had thousands of years to adapt to synthetic pesticides.

But let's be clear--this doesn't mean that synthetics are necessarily dangerous. Rather, it merely weakens the author's argument that if natural pesticides are safe, synthetics must be safe as well.

Please let me know whether this is clear--thanks!

-Steve

[Dazhiw]

Hi,

Thanks for your response. Let's start at the beginning. The author's argument is basically this:
Many natural pesticides aren't harmful to humans, so synthetic pesticides must not be much of a threat (the idea is that the two types of pesticides are so similar that if one is harmless, so is the other). Answer choice (A) provides that people have had thousands of years to adapt to natural pesticides--maybe it's that adaptation that makes natural pesticides harmless. If that's the case, then maybe synthetics could still be a threat, since we haven't had thousands of years to adapt to synthetic pesticides.

But let's be clear--this doesn't mean that synthetics are necessarily dangerous. Rather, it merely weakens the author's argument that if natural pesticides are safe, synthetics must be safe as well.

Please let me know whether this is clear--thanks!

-Steve

Steve,

It took me a long time to finally understand your explanation. Some time it's just better to jump to other questions for a while and come back revisite it again, it's crystle clear now that even a little will weaken the argument.

thank you for the explanation.

best,
Dazhi

[pwfquestions]

I thought A) didn't have an effect on the argument because the conclusion is about synthetic pesticides.

Please explain.

[Rachael Wilkenfeld]

Hi pwf,

Our conclusion references the natural pesticides by talking about "additional threat." Additional compared to what? We use context clues to figure out that it's a threat additional to that posed by natural chemicals. Our conclusion is basically saying that the synthetic chemicals pose no additional harm. In order to harm that conclusion, we want to show that the synthetic chemicals are really different from the natural chemicals. Answer choices (A) through (D) do that by showing a difference between the natural and synthetic. Answer choice (E) is our answer that does not weaken by suggesting a similarity between the synthetic and natural pesticides.

Hope that helps!