#20 - The advent of chemical fertilizers led the farmers in

[Administrator]

Complete Question Explanation

Assumption—CE. The correct answer choice is (E)

Here, the author concludes that if farmers are to significantly improve the soil structure of their fields, then they have to stop using chemical fertilizers. In support of this conclusion, the author points out that when chemical fertilizers were first introduced, the farmers responded by no longer growing “green-manure” crops to rejuvenate the soil. No longer growing green-manure crops resulted in the soil structure of a typical farm field in the region being poor. For these reasons, the author concludes that if farmers are going to significantly improve the soil structure of the fields in this region, they will have to stop using chemical fertilizers.

This is an Assumption question. Since there is no new or “rogue” information in the conclusion, we classify this as a Defender Assumption question. To prephrase for a Defender Assumption question, we need to find the logical gap in the argument. In this case, the only evidence for the conclusion was the effect of the introduction of chemical fertilizers on the behavior of the farmers. The farmers chose not to grow green-manure crops anymore. There is no indication that chemical fertilizers and green-manure crops cannot be used together, yet the argument proceeds as if there is some prohibition. Our prephrase is that the correct answer choice will tell us some reason why chemical fertilizers and green-manure crops cannot be used together.

Answer choice (A): This answer choice tells us that if chemical fertilizers are not used then most farmers will periodically grow green-manure crops. However, it does not tell us what the author assumes, that green-manure crops and chemical fertilizers cannot be used together.

Answer choice (B): Here, the answer choice indicates that chemical fertilizers will not help the green-manure crops grow, but the improved growth of those crops is not the issue. We only care about the green-manure crops because of their effect on the soil structure. The impact of the chemical fertilizers on the green-manure crops themselves is irrelevant to the conclusion.

Answer choice (C): In this case, the conclusion does not require us to know the “most important factor” influencing soil structure. Rather, what we are looking for is something telling us that we cannot simultaneously use chemical fertilizers and grow green-manure crops.

Answer choice (D): Although this answer choice strengthens the conclusion, it is not required for the conclusion to be valid. Recall the evidence from the stimulus that the soil was poor because the farmers stopped growing green-manure crops. It is that evidence that the author relied on, and we need to find an answer choice that tells us it will be necessary for the farmers to stop using chemical fertilizers before they can start improving the soil structure by planting green-manure crops.

Answer choice (E): This is the correct answer choice. Although it does not tell us that it is impossible to use chemical fertilizers and also grow green-manure crops, this answer choice indicates that many farmers simply will not do both. If the farmers were willing to both use chemical fertilizers and grow green-manure crops, then it would not be necessary for the farmers to abandon the use of chemical fertilizers. They would simply be able to grow green-manure crops and improve the soil structure, regardless of their continued usage of chemical fertilizers.

[carnegie49]

Hi,

Could someone please explain the conditional logic that leads to answer choice D?

Many thanks

[David Boyle]

Hi,

Could someone please explain the conditional logic that leads to answer choice D?

Many thanks

Hello carnegie49,

The correct answer is answer E. If you're interested in D (?), D seems to be blaming the chemical fertilizers themselves for damaging the soil. But maybe they don't actually damage the soil, they just fail to put in some nice nutrients that alfalfa might.
As for E, let's diagram the stimulus, with arrows denoting causation or conditional reasoning as the case may be:

Premise: slash green-manure crops poor soil
(So, green-manure crops may cause good soil, since the lack causes bad soil. And good soil may need green-manure crops)

Conclusion: improve soil slash chem. fertilizers

Answer D: Green-manure crops slash chem. fertilizers

Answer D links various elements in the stimulus, as supporter assumptions tend to do.

Hope this helps,
David

[mokkyukkyu]

Hi, so I was not sure between A and E...I liked E better than A, but what concerned me is "many" in E...
Can we think it is equal to "at least"? (which is usally a nec. ass. asnwer)

[Adam Tyson]

The problem with E is alfalfa. We were told that alfala is a green manure crop, but not that it is the only green manure crop. The author didn't have to assume anything about alfalfa specifically, but only about green manure crops generally.

Try the negation of E - many, if not all, farmers WILL grow green manure crops EVEN IF THEY DON'T abandon chemicals. That wrecks the claim that farmers need to abandon chemicals if they want to improve the soil, right?

[PB410]

Hi,
I have a quick question about negating unless statements. I have understood it to be negating the necessary condition. It is diagramed as A----B
negated as A----(no)B
But answer choice E looks like it is negating both the sufficient and the necessary.
many farmers in the region Will... even if the DON'T abandon...
Isn't removing not in the sufficient a negation?
Another example from a previous thread is
unless the package is sent by air, it will not arrive tomorrow.
Negation: The package MAY arrive tomorrow even if it is NOT sent by air.
Isn't the sufficient again negated? I always get confused in negating and trying to understand the meaning of the statement.
Thanks!

[PB410]

I just realized the problem. In the above question, I made made the mistake of forgetting that unless statements are diagrammed as keeping the necessary condition and negating the sufficient.
So the original statement
"People who attempt to diagnose their medical conditions are likely to do themselves more harm than good unless they reply exclusively on scientifically valid information" .

the correct diagram would be

People who attempt to diagnose their medical conditions are NOT likely to do themselves more harm than good---- when they reply exclusively on scientifically valid information.

and the negated statement repeats the sufficient and negates the necessary
A-----(no) B
People who attempt to diagnose their medical conditions are NOT likely to do themselves more harm than good -> even if they do NOT rely exclusively on scientifically valid information .
If someone can confirm, that would be great.

[vascode]

Hello,

The reasoning in your explanation makes sense when I look at the flaw in that angle. But I approached this question in different view and still try to figure out what's wrong with my reasoning.

My choice was (C). And I chose it because I thought the flaw had something to do with the link between soil structure and its quality.

Here was parts that I focused on when reading the stimulus.
Premise : ... the soil structure in a typical farm field in the region is *poor*
Conclusion : to improve the *soil structure*, farmers will need to abandon the use of chemical fertilizers.

So I thought the gap is between the soil quality and structure and linking them would be needed to make this argument make sense.

I think now that (E) makes more sense after reading your explanation but wanted to know if my reasoning process was completely wrong OR (C) is still okay but (E) better.

Thanks,
Yoon

[James Finch]

Hi Vascode,

As an Assumption question, there will be only one correct answer choice, one that is absolutely necessary for the argument to be correct--although by itself, this assumption isn't sufficient to tell us the conclusion is correct. Instead, if the assumption isn't true, then the conclusion cannot be true either. This means that we can use the Assumption Negation technique to attack these questions efficiently and accurately, by negating the answer choices we are testing and seeing if that negation would also lead logically to the negation of the conclusion, or diagrammed:

Assumption Conclusion

Here, if we negate (C), we get:

Soil structure is not the most important factor influencing soil quality Farmers won't need to abandon chemical fertilizers to improve soil structure

As we can see, the scope is off--soil *quality* isn't important to the conclusion, soil structure is. So this doesn't work to negate our conclusion, and is thus an incorrect answer choice.

Whereas (E) negates to:

Farmers would grow green manure crops even when using chemical fertilizers Farmers won't need to abandon chemical fertilizers to improve soil structure

Works perfectly, making it our correct answer.

Hope this clears things up!

[LSAT2018]

I managed to get to the correct answer but was wondering how the 'many, if not all, farmers' part affects the unless conditional statement. Would this translate to if many, if not all, farmers in the region grow green-manure crops, then they abandon the use of chemical fertilizers? The many seems a little off but I chose the answer because there were no other ones, but for the sake of reviewing I would like to clear this up.

Likewise, I am getting caught up with some/most/many/few in the answer choices for conditional statements. When looking at the contrapositives for them, for example if A, then some B, would the contrapositive be if not some B, then not A OR would it be if all B, then not A?