PrepTest 130, Section 4, Question 22
A book tour will be successful if it(30 more words not shown)
Which one of the following(20 more words not shown)
- AThis recipe will(28 more words not shown)
- BIf a computer(38 more words not shown)
- CIf cacti are(35 more words not shown)
- DA house will(38 more words not shown)
- EIf one wears(36 more words not shown)
Reading the argument
A well-publicized tour by an established writer is guaranteed to succeed under the stated rule. Both features together give us that result. The rule does not say that every successful tour must have both features, or that either feature alone is enough.
Julia is established, and her tour succeeded. Must publicity explain the success? Perhaps her existing readers showed up without much publicity. The stated combination is one route to success, not a restriction ruling out every other route.
What we’re looking for
The parallel-flaw question asks us to preserve the whole pattern: two features together guarantee an outcome; we are given one feature and the outcome; then we improperly infer the other feature. An answer that reasons backward in some other way might be flawed too, but we want this particular arrangement.
Working the answers
- A
The recipe will turn out only if it is followed exactly and high-quality ingredients are used. Those are requirements for success. Since Arthur's recipe did turn out, concluding that he used high-quality ingredients follows from the rule. The original never makes publicity a requirement in that way.
- B
The fastest processor and the most memory form a pair that guarantees meeting Aletha's needs, just as publicity and an established author guarantee success. But B gives only the outcome and infers both features. Our original gives one feature as a fact and infers just the missing one.
B also shifts from this year's needs to last year's. That is an additional mismatch, but even if the dates matched, inferring the entire pair would still differ from the original's structure.
- CCorrect
Shade corresponds to being an established writer; frequent watering corresponds to publicity; death corresponds to the successful tour. The rule says that shade and watering more than twice weekly together lead to death. We then learn that the cactus was in shade and died, and the argument infers the other feature: frequent watering.
But the cactus could have died in some other way while in the shade, just as Julia's tour could have succeeded without publicity. Both arguments improperly treat the unconfirmed part of a sufficient combination as required by the observed result.
- D
Dry rot together with poor drainage requires a high water table. The house has both stated problems, so the conclusion follows from that requirement. This is not the original's move from a guaranteed result back to one missing feature of a combination that could produce it.
- E
The suit has both double vents and narrow lapels, the two features the rule says guarantee being fashionably dressed. E supplies both features and reaches the promised result. The original instead supplies one feature plus the result and tries to recover the other feature. E follows its rule correctly.
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