PrepTest 107, Section 3, Question 25
A recent survey showed that 50 percent of(49 more words not shown)
The reasoning above is flawed(2 more words not shown)
- Adraws a conclusion(13 more words not shown)
- Bconfuses a sufficient(5 more words not shown)
- Cis based on(7 more words not shown)
- Ddraws a conclusion(14 more words not shown)
- Econtains premises that(4 more words not shown)
Reading the argument
The word “only” changes what those 35 percent believe.
Half the people say an indictment is enough: if an official is indicted, the official should resign. The other reported belief sets a requirement: an official should resign only if convicted. Someone holding that second belief rules out resignation without a conviction. That is not the same statement as saying a conviction is enough to require resignation.
The conclusion treats the two percentages as though they answer matching questions: how many people favor resignation after an indictment, and how many favor it after a conviction? But the second survey result does not give us that second number.
Think about the people willing to demand resignation after an indictment. They might also demand it after a conviction. For a possible set of responses, all 50 percent in the first group could favor resignation after conviction, and a separate 35 percent could favor it only after conviction. That would give us 85 percent favoring resignation after conviction, compared with 50 percent after indictment. We are not claiming the survey establishes 85 percent. The example shows why it has not established the conclusion.
What we’re looking for
For the flaw question, I would look for an answer recognizing that “if convicted” and “only if convicted” express different beliefs. Simply comparing 50 with 35 overlooks that difference.
Working the answers
- A
Using a sample to learn about a population is not automatically a mistake. We would need some reason to question whether this sample represents the population. More importantly, the argument mishandles the two beliefs even if the sample is perfectly representative. A does not identify that problem.
- BCorrect
A sufficient condition is enough to trigger a result. A required condition is something that must be present for that result. Here, “resign if convicted” makes conviction enough for resignation. “Resign only if convicted” makes conviction a requirement for resignation.
The survey gives the percentage supporting the requirement, but the conclusion uses that figure as the percentage supporting the sufficient condition. Those are different questions. People can regard conviction as enough to require resignation while also thinking some other circumstances require it. The 35 percent figure does not count all such people.
- C
No word needs to change meaning for this mistake to happen. The problem is the different relationships expressed by “if” and “only if.” Both can be perfectly clear, and treating them as interchangeable would still be wrong.
- D
Learning about two beliefs can legitimately support a comparison between them. That general description does not explain this argument's error. We need to notice that one belief in the conclusion differs from the belief actually measured: sufficient grounds for resignation have replaced required grounds.
- E
Different respondents can hold different views without making the survey results contradictory. Fifty percent can give one response and 35 percent another. The error is in what the author concludes from those results, not in an impossibility of both results being true.
More Flaw questions
Learn the LSAT our way
Our platform drills Flaw questions at your level and adjusts as you improve.