LSAT Question Stem

Which one of the following is an error of reasoning in the restaurant manager's argument? 

Logical Reasoning Question Type

This is a Flaw question. 

Correct Answer

The correct answer to this question is E. 

LSAT Question Complete Explanation

The question type for this problem is Flaw, which asks us to identify an error of reasoning in the restaurant manager's argument.

First, let's analyze the argument presented in the passage. The restaurant manager states that they introduced three vegetarian main dishes, and while the first two are frequently ordered, the potato dish is not. The manager concludes that their patrons prefer not to eat potatoes. The structure of the argument is as follows:

Premise: The first two vegetarian dishes are frequently ordered.

Premise: The potato dish is not frequently ordered.

Conclusion: Patrons prefer not to eat potatoes.

An "Evaluate" question for this argument could be: "Are there any other factors that might influence the patrons' choice not to order the potato dish?"

Now, let's discuss the answer choices in detail:

a) concluding that two things that occur at the same time have a common cause

- This answer choice is incorrect because the restaurant manager's error is not about two things having a common cause. The manager is attributing the lack of orders for the potato dish solely to the presence of potatoes.

b) drawing a conclusion that is inconsistent with one premise of the argument

- This answer choice is incorrect because the conclusion does not contradict or disagree with any of the premises. The manager is simply drawing a conclusion based on the observed ordering patterns.

c) ignoring possible differences between what people say they want and what they actually choose

- This answer choice is incorrect because the argument is based on the actual choices patrons make, not on what they say they want. The manager's conclusion is derived from the observed lack of orders for the potato dish.

d) attempting to prove a claim on the basis of evidence that a number of people hold that claim to be true

- This answer choice is incorrect because the argument is not based on the number of people who believe the claim to be true. The manager is making a conclusion based on the actual ordering patterns of the patrons.

e) treating one of several plausible explanations of a phenomenon as the only possible explanation

- This is the correct answer choice. The restaurant manager assumes that the lack of orders for the potato dish is solely due to the presence of potatoes, ignoring other possible factors (such as the cheese or the preparation method) that might influence the patrons' choices.

In summary, the restaurant manager's error of reasoning is treating one of several plausible explanations (the presence of potatoes) as the only possible explanation for the lack of orders of the potato dish. The correct answer choice is (E).