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#23 - Robust crops not only withstand insect attacks more

LSAT Apprentice
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Joined: Thu Aug 03, 2017 11:14 pm
Points: 6


I originally chose D but then switched my answer to B. Could you explain why B is incorrect and why D is correct. I suspect that D is correct because the first sentence is actually the main conclusion.


Jonathan Evans
PowerScore Staff
PowerScore Staff
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Joined: Thu Jun 09, 2016 2:12 pm
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Location: DFW, Texas

Hi, JK615,

In fact, the final statement in this stimulus contains the main conclusion: "growing crops in good soil better than using pesticides."

The evidence concerns the degree to which crops are "robust." The unstated assumption is that there is some connection between planting plants in good soil and growing more robust plants.

This is the connection present in answer choice (D). Notice here that these two concepts, "robust" and "good soil," are both present.

Notice also that in answer choice (B) the strength of the language used: "Insects never attack..."

Remember that we are looking for an assumption on which the argument depends. In other words, the statement in the credited response must contain an idea that is a required but unstated belief that the author has, a statement the truth of which is required for the conclusion to be valid.

Let's revisit our conclusion—"growing crops in good soil better than using pesticides"—and consider the statement in answer choice (B). Is it absolutely necessary that "insects never attack plants in [good soil]" for our conclusion to be valid? Could it be possible that even if insects sometimes attack such plants that it's still a better idea to grow plants in good soil than it is to use pesticides? Yes, the statement in the conclusion could still be true. Therefore, answer choice (B) is not a necessary assumption.

Contrast this answer choice with answer choice (D). Is it necessary that good soil generally produces more robust crops? What if good soil didn't generally lead to robust crops? In this latter case the conclusion would make no sense. There would be no reason to think that using better soil is preferable to using pesticides.

This is the Assumption Negation Test™. Even if you have difficulty articulating/prephrasing the assumption, you can test the answer choices to see how well the conclusion holds up when you negate them. If the conclusion remains possible (even if weakened somewhat) with a negated answer choice, this is an incorrect answer. The credited response on an Assumption question will, if negated, make the conclusion impossible or nonsensical.

I hope this helps!