LSAT PrepTest 44 Section 4 Question 15 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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This Logical Reasoning question is from the October 2004 LSAT.

First, let's make a chain of phrases, as always (you can use much shorter phrases that are a sort of shorthand, but I'm not doing that because you guys probably wouldn't understand what I mean...it's also not usually necessary to write the chain down). This helps us see how the argument progresses:

Artists do contours and hatching differently --> this helps to find forgeries and wrongly attributed originals --> this analysis shows many Michaelangelo works are Clovio's

There is no jump here, no place where the logic breaks down. This isn't that kind of question, it's a "must be true" question. We're not finding a problem with the argument but rather a consequence of the argument, and the question is telling us to assume everything the argument says is true anyway. There also is no real way to pre-phrase this question, since any number of things "must be true" if the argument's statements are true. So, let's go through the answer choices and start eliminating them.

A) Beyond the argument's scope. It says nothing about the contours and hatching being the main things that distinguish artists. It says only that they are do distinguish artists from each other. So, since the answer choice is beyond the argument's scope, it doesn't have to be true as a result of the argument.

B) This is the opposite of what the argument says. It says, as our chain shows, that contours and hatching distinguish not only forgeries from original paintings by a particular artists but also distinguish other original paintings (that aren't forgeries of anything) that are just by artists other than the one we might have thought did the painting. So, this doesn't have to be true.

C) Beyond the scope of the argument. It only says that contours/hatching help to distinguish artists, not that they can always do so. So, it doesn't have to be true that contours/hatching sometimes don't distinguish forgeries from originals.

D) Once again, beyond the argument's scope. The argument says only that some of Michaelangelo's drawings can, by the analysis of contours/hatching, be shown to be Clovio's works. It does not say that, by looking at contours/hatching, it can tell whether any work of art is by Clovio or not. So, it is not necessary that those marks be the same in all of Clovio's works.

E) Correct. This fits the argument's scope and doesn't contradict it, as the other answer choices do. The argument is saying that some Michaelangelo's can, by looking at contours/hatching, be shown to be Clovio's. For that to be true, there must be an "analyzable difference" between the contours/hatching of the two artists. Otherwise, no such determination could be made.

Remember:

1) On almost all arguments questions, making (usually in your mind, once you have some practice in, but in writing on the most difficult questions) a chain of phrases that shows how the argument progresses is very helpful. On "must be true" questions, though, there will be no jump in the logic because the question asks us to assume that the argument is true. So, it can't have that kind of a logical flaw.

2) Pre-phrase when possible but, as we've seen before, don't try to do it when there are many, many possible answers, as is the case with this question.

3) Find answer choices that are the opposite of what the argument's saying (in other words, choices that contradict the argument) or are beyond its scope (talking about things the argument doesn't address). This will eliminate all the wrong answer choices in many cases.