PrepTest 140
[lcid:3659] Prep Test 140 LSAT — Reading Comp — S4
Reading comp
Passage
Questions 20-27 . Physicists are often asked why the image of an . object, such as a chair, appears reversed
Remaining source text redacted.
Passage walkthrough
Passage SummaryTopic: Science
Paragraph 1
While the appeal of the "front-to-back" theory of how mirrors work is understandable, it ultimately fails because a correct explanation needs to include both the mirror and the person looking into it.
Key Lines:
Lines 1-4 - The question/phenomenon is brought up
Lines 4-7 - A first explanation is presented
Lines 14-16 - A second explanation is presented
Lines 21-23 - The Author points out a flaw in the second explanation
Lines 26-27 - The Author explores the appeal of the second explanation
Lines 42-44 - The Author explores another reason for the appeal of the second explanation
Lines 48-51 - The Author states her conclusion about what a proper theory of mirrors must do
Meta-Structure:
Phenomenon/Explanation (or Question/Answer, which is very similar) - Here, the phenomenon is the "reversed" image in mirrors, the question, why does that happen? One explanation is that it reverses around the human field-of-sight axis. Another is that it reverses things front-to-back, but the Author says this is "based on a false premise" (Lines 22-23). Finally, the Author concludes that a proper explanation needs to take both the observer and what mirrors do into account.
Last Thoughts:
First, this is a notoriously difficult passage, so if you struggled, you're in good company! When that happens, rely on the structure and statements of opinion. Those two things will help you get through the difficult passages.
The first paragraph is a little confusing, so we should expect some questions on that—we'll need to head back to figure out what the correct answer is for any questions dealing with the concept of field of sight axes and rotation.
One thing that's absolutely important to think about—the Author's closing statement, where we finally learn her opinion on the subject of explaining mirrors. While two theories are presented, the Author concludes not with the acceptance of one theory over the other, but rather with the adoption of a criterion by which theories should be judged. She concludes that a theory is valid "only if we consider both what mirrors do and what happens when we look into mirrors" (Lines 49-51).
How does this apply to the two theories? We know that she pointed out an appeal of the second theory (the Reverse Image theory) is that it cuts out the observer, so she believes that theory isn't a good one (which lines up with her stating it relies on a false premise). The first theory does rely on the observer to explain how a mirror works—it relies on human vision featuring a vertical axis, explaining the left-to-right reversal. But just because it matches up with a requirement for a valid theory doesn't mean the Author accepts it—she never explicitly does, so we have to be careful about selecting answers that are too accepting of that theory.
Paragraph 1
- Paragraph note
- A question/phenomenon is introduced, along with an answer/explanation
- Views, minor Meta-Structures, and the author's attitude
- Phenomenon - Mirrors reverse images left-to-right instead of top-to-bottom
- Explanation - "Field-of-Sight" explanation - the reversal reflects how human field of sight is rotated (vertical axis)
- Base example - Chair
- Paragraph note
- Another answer/explanations is presented, and the Author gives an opinion on it
- Views, minor Meta-Structures, and the author's attitude
- Explanation 2 - Mirrors reverse front-to-back, which makes sense if you think about the reflected chair as being inside the mirror
- Problem with Explanation 2 - Most notable: Based on false premise, since the "chair" inside the mirror isn't real
- Paragraph note
- Why Explanation 2 is appealing
- Views, minor Meta-Structures, and the author's attitude
- It makes sense with our senses, since we "see" the chair in the mirror and thus think of it as real
- Example - We don't focus on mirrors but on objects in them
- Paragraph note
- Another reason Explanation 2 is appealing, with the Author's rebuttal
- Views, minor Meta-Structures, and the author's attitude
- Scientists try to explain without referring to observer
- Author - When you're trying to explain an observation, you need the explanation to include the observer
While the appeal of the "front-to-back" theory of how mirrors work is understandable, it ultimately fails because a correct explanation needs to include both the mirror and the person looking into it.
Key Lines:
Lines 1-4 - The question/phenomenon is brought up
Lines 4-7 - A first explanation is presented
Lines 14-16 - A second explanation is presented
Lines 21-23 - The Author points out a flaw in the second explanation
Lines 26-27 - The Author explores the appeal of the second explanation
Lines 42-44 - The Author explores another reason for the appeal of the second explanation
Lines 48-51 - The Author states her conclusion about what a proper theory of mirrors must do
Meta-Structure:
Phenomenon/Explanation (or Question/Answer, which is very similar) - Here, the phenomenon is the "reversed" image in mirrors, the question, why does that happen? One explanation is that it reverses around the human field-of-sight axis. Another is that it reverses things front-to-back, but the Author says this is "based on a false premise" (Lines 22-23). Finally, the Author concludes that a proper explanation needs to take both the observer and what mirrors do into account.
Last Thoughts:
First, this is a notoriously difficult passage, so if you struggled, you're in good company! When that happens, rely on the structure and statements of opinion. Those two things will help you get through the difficult passages.
The first paragraph is a little confusing, so we should expect some questions on that—we'll need to head back to figure out what the correct answer is for any questions dealing with the concept of field of sight axes and rotation.
One thing that's absolutely important to think about—the Author's closing statement, where we finally learn her opinion on the subject of explaining mirrors. While two theories are presented, the Author concludes not with the acceptance of one theory over the other, but rather with the adoption of a criterion by which theories should be judged. She concludes that a theory is valid "only if we consider both what mirrors do and what happens when we look into mirrors" (Lines 49-51).
How does this apply to the two theories? We know that she pointed out an appeal of the second theory (the Reverse Image theory) is that it cuts out the observer, so she believes that theory isn't a good one (which lines up with her stating it relies on a false premise). The first theory does rely on the observer to explain how a mirror works—it relies on human vision featuring a vertical axis, explaining the left-to-right reversal. But just because it matches up with a requirement for a valid theory doesn't mean the Author accepts it—she never explicitly does, so we have to be careful about selecting answers that are too accepting of that theory.
Question prompt
In the passage the
Remaining source text redacted.
Why the credited answer is right
Credited answer: D
The notes below walk through why it fits the stem and how to eliminate the rest.
Question Type
Science
Answer choices
-
Aevaluating the experimental evidence Remaining source text redacted.
Why choice A is not credited
Incorrect. (Line 12; Line 16) First, the argument doesn't have experimental evidence—it talks about what mirrors do in the abstract, not through certain studies. Second, left-to-right and front-to-back aren't diametrically opposed—they're just different. -
Bdemonstrating that different explanations Remaining source text redacted.
Why choice B is not credited
Incorrect. (Lines 21-23; Lines 48-51) First, the two theories aren't based on different observations—they're both based on looking in a mirror and seeing a reflection. Second, this answer completely misses the Author's criticism and dismissal of one of the explanations. -
Cdescribing the difficulties that Remaining source text redacted.
Why choice C is not credited
Incorrect. (Lines 48-51) The Author does establish the criterion that must be met for a proper answer to the mirror question—but she doesn't state that this will be difficult. This answer also misses the Author's criticism of one explanation of how mirrors work. -
Dshowing why one explanation Remaining source text redacted.
Why choice D matches the stem
Correct. Question Type:
Main Point
Strategy Overview:
Review the main point and paragraph tags to get a sense of the overall purpose of the passage
Answer Anticipation/Relevant Lines:
The primary concern of any passage is to prove the main point, so we should start our anticipation for this question with that. And from there, we want to abstract away from it to focus on what the Author's specific purpose was. Here, since there was a Phenomenon/Explanation pattern, we should anticipate an answer reflecting that.
The main point here? We didn't get a straightforward Main Point question, but we said:
While the appeal of the "front-to-back" theory of how mirrors work is understandable, it ultimately fails because a correct explanation needs to include both the mirror and the person looking into it.
The Author introduces one theory, pivots to another, criticizes that second one, and then sets up what a correct theory must do—and that the second explanation fails to do. The first explanation, however, meets that criterion for a correct theory—but the Author doesn't commit to saying it's correct or that there aren't other requirements for a correct theory.
Since the Author states explicitly that the second explanation is wrong, and she spends the majority of the passage focused on that, we should expect the answer to highlight that purpose. Let's find something saying that the Author is primarily concerned with debunking an appealing theory of how mirrors work by setting up a requirement for such a theory that it doesn't meet.
Answer Explanation:
(Lines 21-23; Lines 48-54) The passage is primarily concerned with explanations for a phenomenon—how mirrors work. She brings up one explanation—the field-of-sight explanation—but largely abandons casting judgment on it. Instead, she pivots to discussing the front-to-back theory, which is "based on a false premise" and fails to meet the criterion for a proper answer to the question. Since the focus of the passage, and all opinion statements, are criticism of the front-to-back theory, the primary purpose of the passage is to criticize that theory, making this the correct answer.
Key Takeaway:
For Main Point questions that are asking you the purpose or primary concern for the passage—as with all Main Point questions—focus on the Author's opinion statements (if they exist). They'll tell you the main point much more than focusing on background or information presented without opinion. -
Erelating the theoretical support Remaining source text redacted.
Why choice E is not credited
Incorrect. (Line 26; Lines 43-45) The Author does spend Paragraph 3 and the first half of Paragraph 4 talking about why people accept the front-to-back theory, but this answer misses the Author's criticism of that explanation.
What this tests
Discussion
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Why is D correct? 1 reply
Started by alicat6
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PT 19, S4, Q23 2 replies
Started by smilde11