Q10 - When a bird flies,

[Laura Damone]

Question Type:
Inference: Fill in the blank

Stimulus Breakdown:
No argument here, so we just need to break down the facts. Fact 1: When a bird flies, powerful forces converge on it's shoulder joints. Fact 2: The wings must be stable during flight. Fact 3: Stability can't happen unless something balances the powerful converging forces. Fact 4: The only structure capable of balancing the forces is a ligament connecting the wing to the shoulder joint.

Answer Anticipation:
This set of facts is a bunch of conditional statements that can chain together. Flight requires stability, which requires a balancing of forces, which can only be accomplished by the ligament: Flight --> stable --> balance forces --> ligament. The blank that we're supposed to fill begins with the phrase "So that ligament must be." What must that ligament be? It must be the thing that balances the forces necessary for stability during flight.

Correct answer:
E

Answer choice analysis:
(A) Like so many wrong answers throughout LSAT history, this answer would be right, but for the unfortunate "only." Could we infer that the ligament is indispensable to bird flight? Absolutely. Can we infer that it is the only structure indispensable to bird flight? Absolutely not.

(B) Wrong. We can conclude that the ligament is the thing that keeps wings stable during flight, but we can't conclude anything about the reason that they must be stable. In other words, they are necessary for stability, not the reason stability is necessary.

(C) No way. Just because the ligament is a connection between the wing and shoulder doesn't mean that it's the only connection between the wing and shoulder.

(D) No, the ligament responds to the powerful forces. It isn't the source of them.

(E) Aha! Here it is at last. A match for our prephrase, and a perfect summation of the facts in the stimulus.

Takeaway/Pattern:
In most Fill in the blank Inference questions, we're looking for the answer that most logically completes the argument. That means, technically, these are Most Strongly Supported questions, not Must Be Trues. But in practice, Fill in the blank Inference questions function more like Must Be Trues. They're often conditional, very pre-phraseable, and the correct answer almost always ties all the facts together in a neat little package. As is the case for any Inference family question where you can prephrase a conditional statement, be on the lookout for wrong answers that illegally reverse or negate your prephrase (A) or another part of your stimulus (C).

#officialexplanation

[JackieZ905]

Hello Laura,

Since you have mentioned: Flight --> stable --> balance forces --> ligament. And the conclusion is "so that ligament must be____"

I think what we expect to know is ligament---> ?

AC E sounds like ligament --> balance forces --> stable--> flight.

How did you get ligament --> balance forces --> stable--> flight?

How should we interpret "the means by"? Should it be "A-->B" or "A<--B"

Thank you!