#24 - That wall is supported by several joists. The only

[Administrator]

Complete Question Explanation

Parallel Reasoning—CE. The correct answer choice is (A)

This question provides a great opportunity to Double the Conclusion and potentially save a lot of time. Based on two premises, the author draws a very specific kind of conclusion:

• Premise: The only possible cause of the wall bulge is a broken joist.
  
  Conclusion: Therefore, at least one joist must be broken.

The conclusion is qualified in a very specific way—at least one joist is broken. On the correct answer choice parallels this conclusion.

Answer choice (A): This is the correct answer choice, and hopefully an easy one to spot, considering its unique conclusion: At least one of the players must have made a mistake. Much like the conclusion found in the stimulus, this one's based on a similar premise as well:

• Premise: The only possible cause of that grimace is a mistake.
  
  Conclusion: Therefore, at least one orchestra member must have made a mistake.

Answer choice (B): This choice concludes that the first piece "must have been the easiest," which is very different from the "at least one" conclusion found in the stimulus.

Answer choice (C): This one concludes that "the players play well only when...," which is also easily distinguishable from the conclusion found in the stimulus, so this answer choice is incorrect.

Answer choice (D): This is the first incorrect answer choice that presents a conclusion that is somewhat similar to that found in the stimulus: "(at least) One of the players must be able to play the harp." But, unlike the argument found in the stimulus, this one is not based on the notion that the harp is the only possible cause, which reflects the supporting premise from the stimulus.

Answer choice (E): This incorrect answer choice presents a conclusion that looks much like the premise found in the stimulus: "this is the only possible cause."

But that is the only real relationship between this answer choice and the stimulus, so this one fails to parallel and is thus incorrect.

[Alexis]

Hi, could you go into more detail as to why answer E is incorrect? Thanks.

[Jennifer Janowsky]

Sure!

Let's look back at (E): Emotion is the only thing that could have caused the conductor to be angry, because they were playing perfectly.

The problem with (E) is that it fails to state that the only two options that could make the conductor angry would be the emotions or bad playing--this is falsely assumed by the argument. However, the initial argument doesn't make any such false assumptions that you could parallel with this one. Therefore, this answer is not parallel to the stimulus.

I hope that answers your question!

[silent7706]

Hi,

When I diagrammed the stimulus using casual and conditional statements, I came up with different diagrams:

Causal:

P: Broken Joist Bulge
P: Bulge
C: Broken Joist

Conditional:

P: Bulge Broken Joist
P: Bulge
C: Broken Joist

Are these diagrams correct? I'm not sure why their orders seem to be reversed. Perhaps the same relationship can be diagrammed differently using causal or conditional statement? Please advise.

Thanks in advance.

[Zach Foreman]

Silent,
Excellent observation!
You are exactly correct with your diagrams. Well, almost.
Usually, it is pretty clear which way to diagram. If it has causal language, you diagram it as causal and if it has conditional language, you diagram as conditional. The problem here is it has both! "only possible cause." "Only" is conditional reasoning language (indicating necessary condition) and "cause" is of course causal.
The conditional reasoning seems fine "If bulge, then broken joist. Bulge, therefore broken joist". There is a potential problem with the causal as diagrammed. The premises are diagrammed correctly, but it would seem to be a reverse causality error as it says the effect occurs therefore the cause occurs.
So, which do we choose? In this case, it is set up as a premise-conclusion stimulus so I would go with the conditional. In addition, the causal lacks the conditional aspect entirely which really distorts the stimulus.
But this is not so rare (though usually it is easier to figure out which one we should diagram). Remember the first conditional we ever got in class? "If you study you will get an A+". We *could* diagram that as a causal, since it appears that studying causes good grades. But it's probably a better idea to do it as a conditional. And usually, the two diagrams will be opposite each other because conditionals are always the first in time first and then the second in time. But conditionals are not time bound. The two conditionals could be simultaneous or the necessary could be before or after.

[chloemeyers]

Hi! I understand why A is right, but why is D wrong? In the initial explanation it says that D is not based on the notion that playing the harp is the only possible cause, but isn’t someone playing the harp the only possible cause if the song includes harp? I understood this answer choice as a harp player being the only possible cause if a song requires harp. Is "should" in this answer choice the key word, meaning that even if the harp should be played it won’t necessarily be played? Thanks so much!

[Frank Peter]

Hi Chloe,

Since this is a parallel reasoning question, we have to start with an understanding of what the stimulus is saying, and then choose the answer that most closely approximates the logic of the stimulus.

The stimulus starts by telling us a known fact (wall is supported by joists), and concludes that one of the joists must be broken since that it the only thing that could have caused the bulge in the wall.

(D) doesn't start with a known fact, but a conclusion that one of the players must be able to play the harp. It's a conclusion that the speaker reaches from the fact that a piece is being played next week which calls for a harp. (D) doesn't limit the range of causality the way our stimulus does; if it had said "the orchestra would only be playing a song that calls for a harp if one of the members of the orchestra could play a harp" that would be a different story.