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#21 - Prolonged exposure to sulfur fumes permanently damages

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Complete Question Explanation

WeakenX, CE. The correct answer choice is (A)

Some had difficulty finding the conclusion in this stimulus. The conclusion, appearing in the first sentence without any traditional indicator words, is that “prolonged exposure to sulfur fumes permanently damages one’s sense of smell.”

The support offered for this conclusion is a study involving 100 workers from sulfur-emitting factories. These workers were provided various chemically reproduced scents, which they were asked to identify. The workers successfully identified only 10 percent of the scents. In comparison, a control group of 100 workers from “other occupations” were able to identify 50 percent of the scents.

Based on the relatively poor performance of the factory workers, the author reaches a causal conclusion, that prolonged exposure to sulfur fumes caused the workers’ poor performance and, more generally, permanently damages one’s sense of smell. However, there are several questions left unanswered by the argument. For example, what are the “other occupations” held by the control group workers? Why did the study use chemically reproduced scents, and what effect did that have on the test results? And, as with any study offered as evidence on the LSAT, we need to be watchful for other, as yet unstated flaws in the study methodology.

The question stem establishes this as a Weaken—Except question. The four wrong answer choices will attack the causal conclusion, while the correct answer choice will have no effect on the conclusion, or could strengthen it.

Answer choice (A): This is the correct answer choice. This answer choice is tricky, because it plays on our concern about the impact of using chemically reproduced scents. However, it tells us that the scents closely reproduced the corresponding natural scents, even if they did not do so perfectly. So, this lack of perfection may account for the poor results even among the control group, which correctly identified only 50 percent of the scents. However, it does not explain the difference between the 10 percent factory worker result and the 50 percent control group result. And, it does not provide any reason other than the effects of exposure to sulfur fumes to explain the factory workers’ worse performance. Because this answer choice does not weaken the conclusion, it is correct.

Answer choice (B): The stimulus told us that the factories emit sulfur fumes, and the whole point of the study was to determine the effect of the sulfur on the workers’ sense of smell. While we do not know the occupations of the other workers, it appears safe to assume that most of those workers perform their work in an environment with less noxious odors than those that occur in the factories. So, this answer choice weakens the conclusion by suggesting that the factory workers’ poor performance may have been caused by the testing environment, rather than the workers’ ability to smell.

Answer choice (C): If most of the members in the control group had previously participated in a study involving the identification of scents, then it is possible that their prior experience in some way improved their performance in this study. That possibility raises the potential of an alternate cause for the factory workers’ inferior performance.

Answer choice (D): If all of the factory workers participating in the study have been exposed to other noxious fumes in addition to sulfur, then it may be the case that one of those other fumes caused any lost sense of smell suffered by the workers.

Answer choice (E): A weakness in the study was that it did not merely task the subjects with being able to smell the scents, but also to correctly identify them. If the factory workers were less likely to have been exposed to many of the scents used in the study, then it may be the case that the workers can smell—they just lack the knowledge to identify what they are smelling.
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How does A not weaken the argument? If the scents were not perfectly reproduced then it would have made it more difficult to correctly identify the smell. I picked D because the fact that the factories emit other noxious fumes doesn't really have much to do with the argument in my mind.
Adam Tyson
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Thanks for the question, Mike. Let me see if I can help.

First, let's talk about why D does weaken the argument, because on "Except" questions like this we are typical focusing our effort on the wrong answers, because the right answer will have no particular discernible characteristics other than "not" (in this case, "not weaken"). Much harder to tell what you are looking for if you focus on finding the credited response on these!

D weakens the argument by introducing possible alternate causes for our factory workers. The author wants us to believe that it's sulfur that is causing our workers to have less success at identifying the smells. He claims that sulfur has permanently damaged their smellers. But what if it was some other noxious vapors that were doing the damage? Maybe methane? Introducing a possible alternate cause is a great way to weaken any causal claim. With other fumes floating around, how can we be sure that sulfur is the culprit? We can't!

Now back to answer A, which has no effect and is thus the best one for a "weaken-except" scenario. What impact does A have? The smells are not perfect representations might make the study generally bad, but it doesn't do anything to harm the claim that sulfur has permanently damaged the factory workers' sense of smell. The workers are still doing much worse than the other folks at identifying the odors, and A tells us nothing about why the two groups are different. It might tell us why neither group did all that well, but does nothing to address the difference between the groups and nothing to dispel the idea that sulfur is to blame for that difference.

Since "sulfur did it" is what we are looking to not weaken, A is our best choice. It has no impact at all, and that's what we are typically looking for.

Check out some of our other resources on Cause and Effect reasoning, and you'll see more about the classic ways we can attack those stimuli.

Keep your nose up!
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
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