PT73.S2.Q20

AnthonyScalia

Hi guys! I wanted to get some clarification on the logic that makes this answer E rather than D.

The stem is that the argument relies on the assumption, but my current understanding is that neither answer accomplishes this, though E has more issues than D.

The correct answer, E, is saying that the argument /relies/ on the assumption that many of the farmers wouldn't grow green manure unless they abandon chemicals. I believe the argument is still in tact if this is false.

Even if this was untrue, meaning that few or none of the farmers will only grow green manure if they abandon chemicals, the argument could hold for a variety of other reasons. E's reasoning could justify the argument if true, but it also has the potential to not justify the conclusion if true. Just because the farmers won't grow manure without ditching chemicals, doesn't mean they will grow manure if they were to stop using chemicals. I think the test makers designated E as the correct answer with the thought process that "in order to significantly improve the soil structure," the soil must be "rejuvenated," and they /must/ be "rejuvenated" by growing manure, which relies on and will happen if chemical fertilizers are abandoned.

None of the steps in that logic sequence are supported by premises in the passage. "Significantly improving the soil structure" does not to rely on "rejuvenation." "Rejuvenation" does not rely on the growing of green manure. Abandoning chemical fertilizers doesn't guarantee that the green manure will be grown, not to mention that the diction of E states that the principle applies to "many" farmers while the passage refers to simply "farmers" which implies all farmers, or possibly a mere plurality of farmers (neither of which necessarily matches reliance on the actions of "many" farmers.)

D has inconsistencies as well, though fewer than E does, in my opinion.

In order to conclude that chemicals must be removed to increase soil quality, we must be certain that "farmers" not removing chemicals absolutely inhibits "significant improvement in soil structure." D purports that chemical fertilizers "will have destructive effect on soil structure of farm fields." It does not say that there's a chance it will or that it will contribute to destructive effects, but that it will cause destructive effects. If the /end/ effect of something is destructive, it has not shown significant improvement.

That said, if we are supposed to assume (an unfair assumption in my opinion) that the destructive effects are merely a contribution to the net structure of the soil, then the assumption that chemical fertilizers are disruptive is not necessary to conclude that farmers should ditch chemicals to significantly improve soil structure.

Now, I know the culmination of my thought processes lends to the idea that I may be merely overthinking/overanalyzing the text; I don't disagree. I follow the logic that leads one to select E, even though I think it's flawed logic.

I guess the real implication of my question is to find out where and how the line is drawn between relevant logical inconsistencies and their irrelevant counterparts. Unless the LSAC lays out exactly which factors can be considered for assessing logic, there will be an inherent gray area of subjectivity. I won't claim that this question falls in that gray area, but it must exist somewhere.

Any thoughts and opinions are welcome! Thanks for reading

akistotle

I did PT73 a long time ago (one of a few 70s PTs I've mistakenly done without studying much), and now that I think I have pretty good understanding of Necessary Assumption questions, let me try to parse this out
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Stimulus

P1: Before they start using [chemical fertilizers], they had the practice of periodically growing ["green-manure" crops] (like alfalfa) which rejuvenate the soil.
P2: The soil structure became poor because they stopped the practice of growing ["green-manure" crops].
.............("As a result" in the stimulus means "As a result of abandonment of the practice")

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C: They have to abandon the use of [chemical fertilizers].
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Gap in the argument

But why can't they both use [chemical fertilizers] AND grow ["green-manure" crops]? That is what (E) picks up on.

(E) says:

Some farmers ["green-manure" crops] --> /[chemical fertilizers]
= [chemical fertilizers] --> /["green-manure" crops]
*....."Many" = "Some": https://7sage.com/lesson/many-some/

Negation: ["green-manure" crops] AND [chemical fertilizers]

(E) describes a "Not both relationship". (E) is necessary for the argument to stand.
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The negation of (D) does not wreck the argument. The negation of (D): [chemical fertilizers] do not have a destructive effect. Even if this is true, it could be that [chemical fertilizers] prevents farmers from growing ["green-manure" crops]. And that's why they need to abandon the use of [chemical fertilizers].

(D) strengthens the argument, but it is not necessary.
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I hope this helps
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Side note: What is up with LSAT and alfalfa? I think I've seen other LR questions about alfalfa.