LSAT PrepTest 43 Section 3 Question 23 Explanation | Logical Reasoning

I didn't write the following blog post. It was already on the blog when I took over the URL. The following blog post may contain mistakes. -Steve

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Here’s a Logical Reasoning question from the June 2004 LSAT.

The chain of phrases will be crucial here to show a primary point and the subsidiary points, which is what the question’s about. Let’s go sentence by sentence (shortening things up):

Different hormones raise glucose -->Probably due to metabolism -->Brain cells use only glucose --> Glucose low, brain starves

How do we know that the first point is the conclusion? After all, the last sentence often presents an argument’s conclusion. We know this because the other sentences support that first sentence as evidence; they aren’t conclusions, they just support the conclusion. The 2nd sentence explains why many hormones raise glucose (metabolism).; it explains the preceding sentence, in other words The third elaborates on this, saying that the metabolic quirk is that the brain uses only glucose. The last sentence also elaborates on the second, saying what would happen, given that metabolic quirk, if there weren’t enough insulin. All the other sentences explain the first one (the 2nd explains the first and the 3rd and 4th are further explanations); they explain why many different hormones make glucose.


So, let’s look at the choices. A-D are the sentences, in order (rephrased slightly). E is a combination of the last two sentences, again slightly rephrased. We determined above that the first sentence was the argument’s conclusion, and A is almost identical to it, so we know that A is correct.

Take-home points:

A chain of phrases is vital on questions that ask which part of the argument is the conclusion. (Don’t automatically choose a sentence based on its place in the argument; the conclusion could be anywhere.) Find the one sentence which the others are all commenting on/explaining. That sentence is the conclusion.




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