#17 - A positive correlation has been found between the

[Administrator]

Complete Question Explanation

Weaken—CE. The correct answer choice is (C)

In this stimulus, the author explicitly makes a causal argument, coming to the conclusion that the
atmospheric soot in certain cities is probably not the cause of a certain ailment among the residents
of those cities. The author reaches this conclusion despite evidence of a positive correlation between
the amount of soot in the atmosphere of those cities and the frequency of the ailment among the
cities’ residents. The reason the author thinks this relationship is probably not causal is that it is
typically the case that where there is a large amount of soot in the air, then there are also “high
concentrations of many other air pollutants.”

This is a Weaken question. We need to find the answer choice that casts doubt on the author’s
conclusion that the soot in the air in these cities is probably not the cause of the ailment among its
residents. This is an unusual question in which the author presents evidence of a correlation and then
infers that there is not a causal connection. In this case, showing that the alternate causes are not the
actual causes will attack the conclusion, in a reversal of what we normally do in Weaken questions,
which is to promote the idea that an alternate cause is responsible for the effect. So, we are looking
for an answer choice that indicates it is the soot that causes the ailment, rather than the alternate
cause, the other pollutants.

Answer choice (A): This answer choice strengthens the conclusion by showing that where the soot is
absent, the ailment is just as prevalent, attacking the idea that the soot causes the ailment.

Answer choice (B): This conditional rule cannot have any effect on the conclusion, because we do
not know whether the sufficient condition actually occurs.

Answer choice (C): This is the correct answer choice because it shows that the effect, i.e., the
ailment, is present even when the pollutants are not, strengthening the idea that the soot is the cause
of the ailment, contrary to the conclusion.

Answer choice (D): As with answer choice (B), this answer choice cannot have any effect on the
conclusion without our first being told whether the sufficient condition has been satisfied. In this
case, even if the sufficient condition were satisfied, it would still do nothing to attack the conclusion
that the soot is probably not the ailment’s cause.

Answer choice (E): This answer choice strengthens the conclusion by adding additional support to
the idea that pollutants other than the soot cause the ailment.

[mokkyukkyu]

Hello,

I chose C, but at first glance I could not eliminate B. What's the problem with B?
Since question stem is "if true...." if B is true, I think it is still weakner...although the wording is kind of weak ("If" shows possiblity and ""probably" suggests it might not be the case)

[Adam Tyson]

The first problem with answer B is that "If" at the beginning of the answer. That presents a question - is that true? Before we can determine whether this answer does anything to the argument, we have to answer that question, and so the conditional statement by itself does nothing. "If the moon is made of green cheese, then monkeys can fly" - did this statement strengthen the claim that monkeys can fly? Nope, because we don't know if the moon actually is made of green cheese.

The second problem with answer B is that, even if we remove the "if", it still gives us no help, because the stimulus already told us that soot is usually accompanied by other pollutants. If the ailment rarely occurs except where there is a large amount of soot, so what? Are the other pollutants also present? Without knowing that, we still don't know anything more than when we started.

C is better because it eliminates the other pollutants as potential causes of the ailment. If the ailment occurs when soot is present and not many other pollutants are present, that weakens the claim that soot is probably not the cause by strengthening the positive correlation between soot and the ailment and weakening the correlation between other pollutants and the ailment.

[dianahn]

I still don't get why (D) is incorrect.

I understand from the above explanations that when it is a conditional statement and we do not know whether the sufficient condition actually occurs, it cannot strengthen the argument.

But my thought process was: Unlike (B), (D)'s sufficient condition is satisfied according to the premise of the argument ("in cities where there are large amounts of soot in the air, there are usually also high concentrations of many air pollutants." + "A positive correlation has been found ~")

Given that the premise is true, wouldn't the sufficient condition be satisfied and therefore, weaken the argument?

[Beatrice Brown]

Hi Diana! Thanks for your great question

You're correct that in answer choice (D), the sufficient condition is met, so unlike answer choice (B), it is possible for this conditional statement to have an effect on the conclusion of the argument.

However, the necessary condition in answer choice (D) does not actually weaken the conclusion of the argument. The conclusion of the argument is that the soot probably doesn't cause the ailment despite the positive correlation since there are also other pollutants in the air. Answer choice (D) states that it is possible for two or more of the pollutants to each have a causal effect on the ailment. All this means is more than one of the pollutants can have a causal effect on the ailment, but this doesn't mean that soot in particular has an effect on the ailment. Since this answer choice does not actually tell us that soot has a causal effect on the ailment while strengthening the idea that other pollutants do have a causal effect on the ailment, it doesn't weaken the conclusion of the argument.

By contrast, answer choice (C) provides us with a reason to believe that soot is causally related to the ailment by showing us that even when the other pollutants aren't there and soot is present, the ailment is still present. This casts doubt on the stimulus's reasoning that the presence of other pollutants suggests that soot is not the cause of the ailment.

To sum up, great job recognizing the difference between answer choices (B) and (D)! The reason answer choice (D) is wrong is that even though the sufficient condition is met, the necessary condition doesn't weaken the argument. For this question, the correct answer choice either has to show us that soot has a causal effect on the ailment rather than the other pollutants, or that there is a reason to think the other pollutants do not have a causal effect on the ailment.

I hope this helps, and let me know if you have any other questions!

[quan-tang@hotmail.com]

Hi Diana! Thanks for your great question

You're correct that in answer choice (D), the sufficient condition is met, so unlike answer choice (B), it is possible for this conditional statement to have an effect on the conclusion of the argument.

However, the necessary condition in answer choice (D) does not actually weaken the conclusion of the argument. The conclusion of the argument is that the soot probably doesn't cause the ailment despite the positive correlation since there are also other pollutants in the air. Answer choice (D) states that it is possible for two or more of the pollutants to each have a causal effect on the ailment. All this means is more than one of the pollutants can have a causal effect on the ailment, but this doesn't mean that soot in particular has an effect on the ailment. Since this answer choice does not actually tell us that soot has a causal effect on the ailment while strengthening the idea that other pollutants do have a causal effect on the ailment, it doesn't weaken the conclusion of the argument.

By contrast, answer choice (C) provides us with a reason to believe that soot is causally related to the ailment by showing us that even when the other pollutants aren't there and soot is present, the ailment is still present. This casts doubt on the stimulus's reasoning that the presence of other pollutants suggests that soot is not the cause of the ailment.

To sum up, great job recognizing the difference between answer choices (B) and (D)! The reason answer choice (D) is wrong is that even though the sufficient condition is met, the necessary condition doesn't weaken the argument. For this question, the correct answer choice either has to show us that soot has a causal effect on the ailment rather than the other pollutants, or that there is a reason to think the other pollutants do not have a causal effect on the ailment.

I hope this helps, and let me know if you have any other questions!

'In each of the cities where there are large amounts of soot in the air but little other air pollution, the frequency of the ailment is at least as high as it is anywhere else.'

My problem with C is that the 'anywhere else' is undefined.

I can provide a counter example. Suppose there exist only two types of cities
A: cities where there are large amounts of soot in the air but little other air pollution
B: cities where there are little air pollution (including soot)

If there does not exist any city with considerable amount of other air pollution, then comparing A with B does not necessarily lead to any meaningful conclusion regarding soot. Actually, in this case, the frequency of the ailment is at least as high as it is anywhere else, it supports that soot does not cause ailment.

While D directly attack the line of reasoning the stem uses which supposes if 'in cities where there are large amounts of soot in the air, there are usually also high concentrations of many other air pollutants' then 'the soot itself probably does not cause this ailment'.
'If A and B both present and causes C, if B can cause C, A is unlikely to cause C.'

[Luke Haqq]

Hi quan-tang!

I can definitely address why (D) is incorrect and (C) correct.

First, we're given the conclusion, "the soot itself probably does not cause this ailment." Second, the question stem asks us to weaken this conclusion.

This conclusion is about cause and effect, specifically denying or at least suggesting it is unlikely that the soot is the cause of the ailment. One way to weaken that conclusion is to present evidence that the soot may indeed be the cause or a cause of the ailment. This can be further broken down; one way to show this cause and effect relationship is to present evidence that whenever the cause is present, so also is the effect. Another way is to show when the effect is present, the cause always is present as well, rather than an alternative cause. A third way is to show that it's not the case that the cause and effect relationship is actually reversed. A fourth way is to affirm the validity of the data used to make the claim about a cause and effect relationship.

Answer choice (C) states, "In each of the cities where there are large amounts of soot in the air but little other air pollution, the frequency of the ailment is at least as high as it is anywhere else." What this does is it presents the first and second types of evidence. It shows that where the soot is present, so also is the ailment. And it also connects the effect of the ailment with that specific cause and the absence of other causes. By reinforcing a causal relationship of the soot causing the ailment, this weakens the conclusion that "the soot itself probably does not cause this ailment," making (C) the correct answer.

You are right that "'anywhere else' is undefined," but this seems fine given the general terms used in the stimulus, which refers to "soot in the atmosphere of cities." This isn't a reference to cities in a particular place or region, but rather a statement about cities in general. "Anywhere else" includes all other places besides the specific ones being mentioned in (C), which includes the cities mentioned in the stimulus and all other cities.

Finally, answer choice (D) states, "If high concentrations of many different pollutants in a city’s air are correlated with a high frequency of the ailment among that city’s population, then it is possible that two or more of those pollutants each causally contributes to the ailment." This seems close to weakening the conclusion. But it doesn't ultimately weaken the conclusion about "the soot itself" not being the cause. That is, answer choice (D) is admitting that the ailment's cause might a dual-cause or other combination (perhaps one of these is soot), rather than admitting that the ailment is caused by the soot itself. Perhaps more fatal for (D) and making it clearly incorrect, Beatrice notes above that (D) doesn't mention soot at all; all that (D) "means is more than one of the pollutants can have a causal effect on the ailment, but this doesn't mean that soot in particular has an effect on the ailment. ... this answer choice does not actually tell us that soot has a causal effect on the ailment."

It's unlikely that an answer choice that doesn't mention soot will clearly address a causal relationship about its effects, and (D) doesn't do so. (C) clearly does address this relationship, and does so by challenging the conclusion that "the soot itself probably does not cause this ailment."