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Complete Question Explanation

Flaw in the Reasoning. The correct answer choice is (C)

As is customary in the Logical Reasoning sections, this section begins with a fairly simple question, characterized by a straightforward logical structure. While it is often the case that LSAC will pair such a simple stimulus with confusing answer choices, here we are spared that complication.

The stimulus presents an advertisement for GreenBank, in which GreenBank is trying to convince the audience that it costs more to bank at TekBank than at GreenBank. To support this claim, the advertisement points to ATM usage fees. GreenBank gives all of its customers unlimited free ATM use. TekBank, however, charges 25 cents for each ATM transaction.

Notice that GreenBank’s conclusion, that “it costs more to bank at TekBank than at GreenBank,” is very broad. It is about the cost of banking, in general. But the support for the conclusion discusses only ATM fees. These fees are just one of the costs involved with banking. While the stimulus does not provide us with a schedule of the various fees imposed by both banks, LSAC will assume that we understand there is more to the cost of banking than ATM fees.

The question stem indicates this a Flaw in the Reasoning question. We describe the type of logical flaw committed by the advertisement as an overgeneralization from what could be an atypical example. Here, the overgeneralization is the conclusion about the cost of banking generally, from a single example, i.e., ATM usage fees, that could be misleading. For example, it may be that all of the other fees charged by TekBank are lower than the corresponding fees charged by GreenBank. While this type of flawed reasoning is most often seen as an incorrect answer choice in Flaw questions, occasionally, as here, it appears as the correct answer choice.

Answer choice (A): The argument did not include a recommendation. While it is true that the stimulus is labeled an advertisement, and the intended effect of the advertisement is to lure customers from TekBank to GreenBank, the argument contained in the stimulus did not explicitly make a recommendation.

Answer choice (B): Comparative evidence of ATM transaction fees is entirely relevant to the question of whether it costs more to bank at TekBank than at GreenBank. The flaw is not the relevance of the evidence, but rather its narrow focus on just one example of banking costs that may be atypical.

Answer choice (C): This is the correct answer choice, because it describes the error made by the advertisement in drawing a conclusion about the overall cost of banking at these two institutions solely on the basis of the ATM usage fee, a component of the overall cost that may be atypical.

Answer choice (D): This answer choice describes an Error of Division. The argument proceeded in the reverse direction, concluding that because the cost of using an ATM at TekBank is higher, then the cost of banking, in general, at TekBank is higher.

Answer choice (E): The argument does not conclude that a claim must be false. Instead, the conclusion was that the cost of banking at one institution is higher than the cost of banking at another institution. Further, the premises did not mention an absence of evidence.
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I know this flaw is an overgeneralization, but I am wondering why D is wrong?
 Rachael Wilkenfeld
PowerScore Staff
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Hi cxmss170,

Good question. The difference between errors of composition and division can be tricky. Errors of composition are errors that assume that what applies to a part applies to the whole. That's what is going on in this stimulus. The advertisement is saying that what applies to the part (ATM fees) applies to the whole (overall banking cost). Errors of division as described in answer choice (d) are errors that are assuming that because something applies to the whole, it must apply to each of the parts. An example would be something that says my computer is the fanciest computer ever made, so each key on the keyboard is the fanciest key ever made. Our stimulus here is about moving from the part (ATM fees) to the whole (banking fees) instead of from the whole to the part.

Hope that helps!

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