PT19.S4.Q24 - the wall is supported by several joists

megsvyas_OVO

http://7sage.com/lsat_explanations/lsat-19-section-4-question-24/
Hi friends! I want to make sure that my reasoning is on the ball for this question, since I got it wrong the first time around.

Clarification before you read on: everything in parenthesis is taken from the stimulus, and anything not in parentheses is from the respective answer choice. I mostly need help distinguishing more clearly, A, D, and E from each other.

(A): At least one of the players in the orchestra (at least one of the joists in the wall) must have made a mistake (must have broken), since nothing else would have made the conductor grimace in the way she just did (since nothing else could have caused a bulge).

(B) doesn't match up a "fault" or a "cause" with why something must have occurred, and there is no "at least" element, either; (C) this seems pretty out of scope, especially with the X do Y only when Z

(D): This is the answer I incorrectly picked at first, with some hasty logic like: "Oh, if they are playing a piece of music that has a harp (if there is a bulge), then at least one of the players must play the harp (just like at least one of the joists must be broken). VERY BAD, I know, and answer choice (A) matches up much better. Not to mention, that (A) correctly matches the stimulus in its noting of "at least" and (D) notes "one" -- which is not a correct match.

(E) this also seems out of scope, but has those tricky, creepy, psych elements that JY talks about. "The emotion of the music is the only thing" (could be equated with the joist being the only thing), that could have caused the conductor to look so angry (that could have caused the bulge) just then, since the orchestra was playing perfectly. SEE, here there is no parallel available for the "just then" and the "since the orchestra was playing perfectly" - there is no "the wall was fine and then suddenly there was a snap noise" and so "just then, the joist could have been the only thing for the bulge," etc.

Am I making any sense?

I'm usually totally fine with these types of questions. Any thoughts?

NYC12345

D is not incorrect because it says "one." Rather, it is incorrect because it states that a harp "should" be played, instead of "is played."

c.janson35

Something else I think is important to note:

This is a really simple argument, just cleverly disguised:

P1: A-->B
P2: A
-----------------------
C: B

The reason that it's disguised is that the language the stim uses gives us both P1 and P2 slyly in the same sentence.

"The only thing that could have caused the bulge *the wall now has* is a broken joint"

That is: If bulge occurred, then there must have been broken joints.

How do we know the conclusion is true, that there's broken joints?
Because of the part above that's in **: it tells us the sufficient was satisfied.

The only answer that comes close to this is A.

Hope this helps sort out this question a little bit more!

megsvyas_OVO

@c.janson35 thanks for the kickass explanation!! I can't believe I didn't pick up one of the most basic arguments in disguise. @alexandergreene93 thanks a lot for clarifying that, too! I need to train myself to be more alert about the nuances in these questions rather than just going for a feel of the structure/argument.