Logical reasoning PrepTest 141 · Section 4 · Question 17

Incorrect. This answer strengthens the argument by finding places without soot (a potential alternative cause) but with pollutants (the implied cause from the stimulus) where the effect is still present.

Incorrect. This answer shifts away from the language in the stimulus (a positive correlation between soot and the ailment) to talking about the ailment "rarely" occurring except where "large amounts" of soot are present.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Weaken

Stimulus Summary:
Soot is correlated with other air pollutants and with a certain ailment. Therefore, soot probably doesn't cause the disease.

Answer Anticipation:
Interesting argument! It starts out like a traditional correlation/causation jump, but then it zags a bit. Instead of concluding that soot is the cause of the ailment, it states that it isn't because of high concentrations of other pollutants—in other words, there are alternative potential causes for the ailment. At its heart, however, this argument is still trading in correlations and causation—these other pollutants are correlated with the ailment, so one of them is probably the cause. And it also has brought up an alternative cause—the soot itself. So the correct answer will likely provide information suggesting the soot itself is the cause of the ailment, or these other pollutants aren't.

Thinking about the common ways to weaken a correlation/causation flaw, we can see that one is much more likely than the others here. Since the argument already brought up its own alternative cause, that can factor into the correct answer, but it probably won't be by itself what we need to look for. And it's almost certainly not reversed causality—a respiratory ailment doesn't cause pollution. So the correct answer will likely feature a counterexample—a place where there's soot but no other pollutants and the respiratory ailment is common; or a place where there's other pollutants but no soot and the respiratory ailment is rare.

Answer Explanation:
This answer brings up a counterexample that highlights the likelihood of soot being the culprit. If there are cities with soot but no other pollutants and the ailment is prevalent, then those other pollutants aren't likely the cause, and the soot more likely is.

Key Takeaway:
When a Weaken question itself raises a potential alternative cause and picks one over another, there's a good chance that the correct answer will highlight an example of the disfavored cause being present with the effect when the favored cause is absent. This is a specific application of the counterexample answer choice for correlation/causation flaws, and it's more important to understand that concept than to memorize this particular pattern! Work with it to see how these ideas intersect to enhance your understanding for all Weaken questions that feature a correlation/causation flaw.

Incorrect. This answer doesn't speak directly to whether soot itself is the culprit or the other pollutants are—just that more than one pollutant could be responsible for the ailment. Without tying directly into the debate between soot and other pollutants, this answer doesn't provide enough information to affect the argument.

Incorrect. If anything, by raising even more potential causes of the ailment, this strengthens the conclusion that soot—one particular pollutant—isn't the cause.