LSAT 13 - Section 2 - Question 26

Here we have a flaw question, which we know from the question stem: “The reasoning in the argument is most vulnerable to criticism on which one of the following grounds?” Right away we know our correct answer has to do two things: be descriptively accurate, and describe the flaw of the stimulus. We also know what the wrong answers will do - describe reasoning flaws we’ve seen before, but don’t like up with our stimulus. Once we have a clear understanding of the questrion’s objective, we can proceed into structural analysis of the stimulus.

The stimulus begins with an if-then statement: if Blankenship switches suppliers, they will not turn a profit. Based on this sentence our speaker concludes that if Blankenship does in fact show no profit, it must have been because they switched suppliers.

Diagramming the relationships can help us see the conditional reasoning mistake being made. While we know that a switch in suppliers guarantees a lack of profit, we cannot simply switch around our sufficient and necessary conditions in the conclusion. The evidence presented by the author tells us that S (switch) → /P (no profit).

From here we can conclude only a few things. We could correctly conclude the contrapositive to be the case, that if we do in fact turn a profit we know the company has not switched suppliers during their production run (P → /S). We also know that if the switch occurs profit will be affected. However, we are not able to draw the conclusion that because we have the necessary condition of no profit does not mean we can confirm the existence of our sufficient condition - switching suppliers.

Knowing our speaker mistakes the information we can conclude from a conditional relationship, we can proceed into the answer choices.

Answer Choice (A) Answer choice A is not descriptively accurate. By accusing our speaker of circular reasoning, this answer claims the argument uses its conclusion as evidence for the argument. Without a statement telling us “the conclusion is correct because the conclusion is correct,” we can eliminate this answer choice from consideration.

Correct Answer Choice (B) This is exactly what we are looking for. This descriptively accurate answer choice correctly points out the mistaken conditional reasoning made in the stimulus. Simply because we know S → /P, this does not mean we can just switch the arrow in the opposite direction like our speaker does in the conclusion.

Answer Choice (C) This answer choice is also not descriptively accurate. Rather than shifting the meaning of a word over the course of the argument, our speaker confuses the direction of the relationships between terms that remain consistent in meaning.

Answer Choice (D) Answer choice D is not descriptively accurate. We have no information to determine whether or not Blankenship represents an exception case or a run-of-the-mill operation. Even still, Blankenship being a unique case would not change the conditional flaw presented in the author’s reasoning.

Answer Choice (E) This is not what we are looking for. Accusing the speaker of failing to consider some third possible event does not identify the mistaken reversal occurring in the stimulus. This answer choice aligns with the common correlation/causation flaw often presented in flaw questions - but that is not the issue here.