LR Question 17 Explanation
QUESTION TEXT: A positive correlation has been found between the…
QUESTION TYPE: Weaken
CONCLUSION: Soot probably doesn’t cause the ailment.
REASONING: In cities with lots of soot, there are usually lots of other pollutants.
ANALYSIS: The argument said there’s merely a correlation between the ailment and the soot, and other pollutants are the cause. You’re supposed to weaken the argument by showing this correlation is actually significant. There are at least two weak points to the argument:
- The author only showed it’s possible the other pollutants are the cause. You can weaken the argument by showing they in fact aren’t the cause.
- The author only said that soot is usually accompanied by other pollutants. There may be cities with soot, but without other pollutants. What happens in those cites?
___________
- This strengthens the argument. The author wanted to show the other pollutants were the cause. This answer suggests they are, because the ailment occurs even where soot is absent but the other pollutants are present.
- This would help, if we knew that the ailment only occurs where soot is present. But the stimulus didn’t say that. The ailment is correlated with soot, but it’s possible it exists even without soot.
- CORRECT. This weakens the argument by showing that the ailment exists even when other pollutants aren’t there. So perhaps soot is the cause.
- This is complex, but it doesn’t mean anything relevant. I’ll explain its meaning with an example.
Example of situation: The pollutants smoog, snarf and blug are all correlated with a certain ailment. Therefore it’s possible that both snarf and blug each can cause the ailment. - This strengthens the argument. The author is trying to show that soot is not the cause. This supports that idea by showing that other pollutants may be the cause.
More Resources for Weaken Questions
- Intro Course lesson: This intro course lesson covers Weaken questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers weaken questions.
Hi,
I’m extremely confused by the “Correct Answer” here. When doing this section, I thought none of the answer questions were convincing, so I agree on the explanations for why A, B, D, and E are incorrect. However, C doesn’t seem like the best answer at all because it says if soot is high and there are little other pollutants then “the frequency of the ailment is at least as high as it is anywhere else.” The section in quotes, to me, clearly means that the ailment is just as frequent as any other place on Earth. In other words, there is no notable presence of the ailment in areas with high soot and low alternate pollutants. This would strengthen the argument in the stimulus.
I ended up choosing B even though I knew it was a weak option, it still seemed better than option C to me.
Best,
Peter.
Hi Peter, I can definitely see where the confusion is coming from. C is phrased in a tricky way.
I think the key issue is how “as high as it is anywhere else” is being interpreted.
The stimulus sets up a comparison among a group of cities with large amounts of soot. It then says that these cities usually also have many other pollutants, which is the basis for the argument’s conclusion that soot probably isn’t the cause.
The first issue with your reasoning is that C isn’t comparing the cities with no other pollutants to every other place in the world.
The stimulus is talking about cities with high soot. Answer C isolates a subgroup within the same group: cities with high soot but little other air pollution. So “anywhere else” is best read as referring to the other cities in that comparison set (those with high soot and many other pollutants) – not to every place on Earth in some abstract sense.
That means C is saying: even in the soot-heavy cities without the other pollutants, the ailment occurs just as frequently (or more frequently) as in the other cities. That directly weakens the argument, because the argument’s whole point was that the other pollutants might explain the correlation. If the ailment remains just as common when those pollutants are removed, soot becomes a much more plausible cause.
Another issue is that I’m not sure where the “no notable presence” comes from. “At least as high” doesn’t suggest a low rate or 0. It suggests the opposite: a rate equal to or greater than the comparison cities.
As for B, it just gives us a hypothetical that doesn’t help us break down the facts. It says if the ailment basically only occurs when there’s soot, it’s probably due to soot. But we don’t know whether that’s true or not, and B doesn’t help us conclude whether it’s true.
I hope that helps! Let me know if you have further questions.
I am still confused about option D. Doesn’t that weaken the argument by making soot a potential cause for ailment along with the other air pollutant? The conclusion of the paragraph is that soot probably does not cause the ailment, but D shows that just because other air pollutant could cause the ailment does not mean soot is not an additional cause to the ailment.
For D, if there are many different pollutants available, and multiple pollutants cause the ailment, doesn’t that mean that soot itself could cause the ailment (because the argument argues that multiple present pollutants means that soot doesn’t cause the ailment?)
And for the correct answer, C, doesn’t this ignore the possibility that there could be some non-air pollutant that correlates with soot levels, but is the true cause of the ailment?
Thanks!
The problem with D is that there couple be 1,000 pollutants. In such a case merely having 2-3 pollutants as a cause doesn’t mean one of them is soot.
For C, the answer doesn’t need to prove the argument conclusively wrong. It merely has to “most weaken” the reasoning. C strongly suggests soot is the cause, because it shows the problem is constant where soot is constant, even if other pollutants vary.
Note: This is an old comment but I wanted to clarify the point.