Logical reasoning PrepTest 140 · Section 2 · Question 4

Incorrect. If anything, the concentration of health issues among recipients of specific vaccines instead of all vaccines calls the coincidental nature of these illnesses into question, undermining the argument.

Incorrect. This answer might provide a reason to believe that certain vaccines are less than necessary, but it doesn't address the connection between them and serious health problems developed after receiving them, so this answer is out of scope.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
Opposing point Ð Some people have developed serious health problems after getting vaccines, so they're not safe
Physician Ð Even if true, enough people get vaccines that some will coincidentally get sick right after, so the stories aren't a reason to be wary of vaccines.

Answer Anticipation:
Underlying this entire argument is a debate over causality—does a correlation between serious health problems and getting a vaccine prove that vaccines cause serious health problems? Some say yes, whereas the Physician says no.

Since the Physician takes the stance that there is no causality here, and we're asked to strengthen her argument, we're actually trying to weaken that causal relationship. This will strengthen the Physician's argument that the causal relationship doesn't exist. We can weaken a causal argument through some common means:

(1) ID an alternative cause
(2) Provide counterexample (cause without effect; effect without cause)
(3) Bring up reverse causality (this answer is unlikely because of the timeline—it's noted the serious illnesses happen after the vaccines)

Answer Explanation:
This answer establishes that the "baseline" level of serious illness isn't changed by receiving a vaccine. In other words, this answer establishes a counterexample—people who don't have the supposed cause are just as likely to have the effect as those with the supposed cause. That undermines the causal connection, strengthening the argument that one doesn't exist, as the Physician states.

Key Takeaway:
Strengthen and Weaken questions frequently deal in causality. Here, interestingly, the conclusion was that a causal relationship didn't exist. Since we were tasked with strengthening an argument against causality, we could flip that around and view it as weakening the causal relationship, which led us to the correct answer.

Incorrect. This answer doesn't address whether the vaccines were causally related to those illnesses, so it's out of scope of the argument.

Incorrect. First, there's no indication that what is true of medications will also be true of vaccines. Second, a "few cases" isn't enough to support the causality here. Third, if anything, this supports the opposing view that the vaccines are causing these illnesses by bringing up similar situations where that was the case.