PrepTest 142, Section 1, Question 25
Student: If a person has an immunity to(39 more words not shown)
The student's argument is most(13 more words not shown)
- AEverything morally right(27 more words not shown)
- BAdvertisers try to(26 more words not shown)
- CIsabel said that(27 more words not shown)
- DWhen business owners(27 more words not shown)
- EStudies show that(27 more words not shown)
Reading the argument
Having no harmful symptoms doesn't automatically mean immunity.
Immunity would explain the result, but what if someone received so little exposure that it didn't produce symptoms? That's a possibility to consider, not a claim about what happened to these people. The given rule makes immunity one way to avoid symptoms. It doesn't make immunity the only way.
What we’re looking for
The argument takes the result—no harmful symptoms—and works backward to that one proposed explanation. For the parallel flaw, look for a rule saying a condition produces an outcome, followed by that outcome and an unsupported conclusion that the condition must be present. We'll need the same direction of the mistake, not merely another flawed argument.
Working the answers
- A
The first rule goes from morally right to just. A matching mistake would observe that an action is just and conclude that it is morally right. Instead, A introduces actions that benefit everyone but are not just, then draws a conclusion about morally right actions not benefiting everyone. That is a different, unsupported move involving a third category, not the observed-result inference in the original.
- B
This does contain a rule: advertisers try to persuade. But it starts with people who are not advertisers and concludes that they don't try to persuade. It removes the starting condition and wrongly removes the result. The original observes the result and wrongly infers the starting condition. Those are different directions of reasoning.
- C
This also includes a rule: medication cures or alleviates symptoms. The argument treats Isabel's continuing illness as failure of that result, then concludes that she didn't take the medicine. That differs from observing a result and inferring that the medicine was taken. There is also a problem equating continuing illness with no relief: symptoms could improve without the illness disappearing. Neither move matches the immunity argument.
- DCorrect
Excessive taxes make owners less willing to expand. The argument observes reduced expansion and concludes that taxes must be excessive. High taxes play the role of immunity, and reduced expansion plays the role of no harmful symptoms: the predicted outcome appears, so the argument assumes its named condition explains it.
But perhaps a war made owners reluctant to expand. Just as a low exposure could explain a lack of symptoms without immunity, another problem could explain fewer expansions without excessive taxes. Both arguments mistake one explanation for the only explanation.
- E
This infers that handwashing has little value from how often doctors do it. It doesn't give a rule connecting a condition to an outcome and then infer the condition from observing the outcome. Professional behavior and the value of a practice are being connected in a different way.
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