#24 - Global Reference, Must Be True, Purpose

[Administrator]

Complete Question Explanation
(See the complete passage discussion here: lsat/viewtopic.php?t=12412)

The correct answer choice is (D)

This question asks for the author’s main purpose in writing the passage. The author has written this passage to present the question of what mirrors do, present two explanations, and point out the insufficiency of the second explanation, based on what the author believes is required of a proper explanation of what mirrors do and how they work.

Answer choice (A): The author describes two different explanations of a phenomenon; there is no real evaluation of any experimental evidence, but merely descriptions. Further, the two explanations are clearly different and distinguishable, but they are not diametrically opposed.

Answer choice (B): The author provides no demonstration; the different explanations are described. Additionally, both explanations are based on the same sort of observations, so this choice can be confidently ruled out of contention.

Answer choice (C): With regard to the front-to-back explanation of mirrors, the passage does not really describe difficulties that must be overcome, but rather an explanation that, according to the author, does not properly address the issue (because of failure to consider the observer).

Answer choice (D): This is the correct answer choice. As prephrased above, part of the author’s main purpose in writing this passage is to point out why the front-to-back explanation does not sufficiently address the issue of what mirrors do and what happens when we look into them.

Answer choice (E): The author does not relate the support for an explanation to the acceptance of that explanation, so this choice fails the Fact Test and cannot be the right answer to this Must Be True question.

[knelchr]

Hi there.

In saying that an adequate explanation must consider "both what mirrors do and what happens when we look into mirrors," wouldn't it be more accurate to say that the author is primarily concerned with explaining the deficiency of relying on either explanation alone? I was hung up on the fact that answer choice D only focuses on the second explanation (which I do recognize the author evaluated in more detail). However, I ultimately selected B, thinking "different empirical observations" referred to those with vs. without consideration of what the observer does (e.g., moving their head). Is this distinction ultimately more theoretical than empirical?

Appreciate your help!

Christian

[Jeff Wren]

Hi Christian,

First, if you haven't already done so, I'd recommend reading the complete passage explanation found here:

viewtopic.php?t=12412

This passage can be quite difficult to follow. In fact, it is listed as an honorable mention on our list of the hardest RC passages of all time.

One thing that makes this passage hard to follow is that the first paragraph introduces the field-of-sight explanation, but that topic is never mentioned again in the passage. Instead, the rest of the passage focuses on the second explanation, the front-to-back explanation.

You asked:

In saying that an adequate explanation must consider "both what mirrors do and what happens when we look into mirrors," wouldn't it be more accurate to say that the author is primarily concerned with explaining the deficiency of relying on either explanation alone?

No, the deficiency mentioned is specific only to the second explanation. The first explanation does not have this deficiency, because the first explanation does include what the viewer does, for example, "the viewer rotates his or her field of sight in turning from the object to the reflected image" (lines 6-7). Again, the author has no problem with the first theory, only the second.

Answer B is wrong for several reasons as discussed in the explanation above. The differences in the explanations are theoretical and are not based on different empirical observations. Also, the main point/focus of the passage is only the second/front-to-back explanation and its problem. The first explanation is largely irrelevant to the passage beyond it mention in the first paragraph. The first explanation is a bit of a red herring, because a reader would likely assume that it would be the focus of the passage, but it is not.