PrepTest 103, Section 1, Question 24
That wall is supported by several joists.(27 more words not shown)
Which one of the following(12 more words not shown)
- AAt least one(26 more words not shown)
- BThe first piece(24 more words not shown)
- CThe players play(21 more words not shown)
- DOne of the(31 more words not shown)
- EThe emotion of(24 more words not shown)
Reading the argument
The wall is bulging, and we're told only a broken joist could have caused that. Then at least one joist must be broken.
This reasoning works. We don't need to know exactly which joist broke, or whether several did. The visible result and the stated restriction on its cause are enough to establish that at least one broke. If none had, the only possible cause of the bulge would be absent.
What we’re looking for
I might question that exclusive explanation when inspecting an actual wall, but here it's a premise. The task is to match the reasoning we're given. Look for an observed result, a statement that only a particular kind of event could produce it, and a conclusion that at least one such event occurred. An answer merely saying something “must” be true isn't enough; it needs the premise that makes the conclusion follow.
Working the answers
- ACorrect
The conductor's grimace matches the wall's bulge. A player's mistake matches a broken joist. The statement that nothing else could have produced that grimace supplies the same restriction as the original's claim that only a broken joist could have produced the bulge.
Since the conductor did grimace, at least one player must have made a mistake. We don't need to identify the player, just as we don't need to identify the broken joist. The conclusion comes first in A, but rearranging the sentences doesn't change the reasoning.
- B
Making fewer mistakes on one piece doesn't establish that the piece was easiest. Perhaps the orchestra practiced it more. We would need a rule saying that being easiest is the only explanation for that performance, and B gives no such rule. “The only piece” identifies a unique observed result; it doesn't establish the unique cause that the original supplies.
- C
This moves from a tendency—mistakes when players dislike the music—to an absolute restriction on when they play well. It doesn't report a particular successful performance and use a given restriction to explain it. The original applies its stated rule to an observed event; C tries to establish a general rule from a tendency.
- D
The composer calls for a harp, but that doesn't establish that a current player can play it. Perhaps someone is expected to learn before next week's concert, or the orchestra plans to bring in another musician. A requirement in a planned performance isn't evidence that the ability already exists. The original starts with an actual result, not something someone hopes or intends will happen.
- E
A perfect performance rules out mistakes as the explanation for the anger. It doesn't rule out every explanation except the music's emotion. The conductor could be angry about something else. The original gives us the exclusive-cause claim as a premise and then uses it. E tries to establish an exclusive cause by eliminating just one alternative.
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