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
It can be inferred
Remaining source text redacted.
Why the credited answer is right
Credited answer: E
The notes below walk through why it fits the stem and how to eliminate the rest.
Question Type
Science
Answer choices
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Asuccessful because it is Remaining source text redacted.
Why choice A is not credited
Incorrect. (Lines 27-28; Lines 34-36) First, the passage states that this explanation is successful only "to a point" (Line 28), and this answer fails to include that caveat. Also, the Author states that the front-to-back theory is "quite successful" at explaining what a mirror does to a point, but it's not because it reconciles incongruous facts. The passage does note that mirrors present us with images that are "contrary to fact," but the front-to-back theory isn't based on this—rather, it attempts to explain it. -
Bsuccessful because it rejects Remaining source text redacted.
Why choice B is not credited
Incorrect. (Lines 27-31; Lines 34-36) First, the passage states that this explanation is successful only "to a point" (Line 28), and this answer fails to include that caveat. Second, the passage notes that the front-to-back explanation seems natural because it aligns with us being accustomed to dealing with our mental constructs rather than the primary sense perception on which they're based, so this answer contradicts the passage. -
Csuccessful because it involves Remaining source text redacted.
Why choice C is not credited
Incorrect. (Lines 4-7; Lines 27-28) This answer describes the left-to-right explanation. Also, the passage states that this explanation is successful only "to a point" (Line 28), and this answer fails to include that caveat. -
Dsuccessful only to a Remaining source text redacted.
Why choice D is not credited
Incorrect. (Lines 26-28; Lines 44-45) This answer correctly includes the caveat that the front-to-back theory is successful at something only to a point. However, it's not because it matches with traditional explanations from physicists. That seems to be referencing the argument in Paragraph 4 about what motivates some physicists to accept it. -
Esuccessful only to a Remaining source text redacted.
Why choice E matches the stem
Correct. Question Type:
Must Be True
Strategy Overview:
Reiterate the Author's opinion on the explanation in question, then find an answer reflecting it
Answer Anticipation/Relevant Lines:
When a passage falls into the Phenomenon/Explanation pattern, there's a very good chance that the Author is going to state her opinion on the explanations raised. This passage is no exception.
The Author's opinion of the front-to-back theory, however, is pretty nuanced and spread throughout three paragraphs. In Paragraph 2, she states that the explanation "is clearly based on a false premise" (Lines 22-23). Paragraph 3 sees her exploring why the explanation "appeals strongly" to many people (Line 26)—because it "is quite successful" (Line 27) at explaining what a mirror does in a way that matches how "we are accustomed" (Line 29) to thinking about our senses. It also is "motivated in part" by the "desire to separate the observer from the phenomenon" (Lines 43-45).
However, the Author believes that addressing both "what mirrors do and what happens when we look into mirrors" (Lines 50-51) is necessary ("only if") in explaining how mirrors work, and thus the front-to-back theory ultimately fails.
That's a lot, so let's stay flexible as we work through the answers!
Answer Explanation:
(Lines 26-28; Lines 48-51) The Author notes that the front-to-back explanation is successful to a point in Paragraph 3. However, she goes on to highlight that it can't fully explain what a mirror does because such an explanation is proper "only if" it considers both what a mirror does and what happens when someone looks into it. The front-to-back explanation only does the former but not the latter. This answer is therefore correct.
Key Takeaway:
The correct answer here is interesting. It attaches a detail raised in one paragraph to the Author's overall main point. This highlights the importance of always keeping the Author's main point in mind when answering questions in RC, unless the question is specifically asking about a separate viewpoint.
What this tests
Discussion
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Started by clairesunday5
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Why is B wrong? 1 reply
Started by manvir