LSAT Explanation PT 26, S3, Q8: Grasses and woody plants are planted

LSAT Question Stem

Which one of the following is an error of reasoning in the argument? 

Logical Reasoning Question Type

This is a Flaw question. 

Correct Answer

The correct answer to this question is E. 

LSAT Question Complete Explanation

First, let's analyze the argument in the passage. The argument can be summarized as follows:

1. Grasses and woody plants are planted on dirt embankments to prevent erosion (premise).

2. Mowing the embankments causes grass clippings to pile up (premise).

3. Grass clippings smother woody plants, causing their roots to rot and attracting rodents that damage the roots (premise).

4. The roots of woody plants are essential for preventing erosion (premise).

5. Therefore, bringing in predators to eradicate the rodents will prevent erosion of the embankments (conclusion).

The question type is Flaw, which asks us to identify an error of reasoning in the argument. Now, let's evaluate the argument by asking the following question: "Does eradicating rodents address all the causes of erosion mentioned in the passage?"

Now, let's discuss each answer choice:

a) Two events that merely co-occur are treated as if one caused the other.

This answer choice is incorrect because the passage does establish a causal relationship between grass clippings and both root rot and rodent attraction. The argument does not confuse correlation with causation.

b) A highly general proposal is based only on an unrepresentative set of facts.

This answer choice is incorrect because the passage provides specific facts about the causes of erosion and does not make a general proposal based on an unrepresentative set of facts.

c) The conclusion is no more than a restatement of one of the pieces of evidence provided to support it.

This answer choice is incorrect because the conclusion (bringing in predators will prevent erosion) is not a restatement of any of the premises provided in the passage.

d) One possible solution to a problem is claimed to be the only possible solution to that problem.

This answer choice is incorrect because the passage does not claim that bringing in predators is the only possible solution to the problem of erosion. It merely suggests that it will prevent erosion.

e) An action that would eliminate one cause of a problem is treated as if it would solve the entire problem.

This is the correct answer choice. The passage suggests that bringing in predators to eradicate rodents will prevent erosion, but it does not address the other cause of erosion mentioned in the passage: grass clippings smothering woody plants and causing their roots to rot. The argument assumes that eliminating one cause (rodents) will solve the entire problem of erosion, which is a flawed reasoning.

In summary, the correct answer is E because the argument treats an action that would eliminate one cause of a problem (rodents) as if it would solve the entire problem (erosion) without addressing the other cause (grass clippings smothering woody plants).