LSAT 140 | Section 1 | Logical Reasoning: Q14

LR Question 14 Explanation

QUESTION TEXT: Some philosophers explain visual perception by…

QUESTION TYPE: Parallel Reasoning

CONCLUSION: It can’t be true that we perceive an object by creating a mental image of the object.

REASONING: We’d need a new self to perceive the mental image. The inner self would need its own mental image, and this would go on to infinity.

ANALYSIS: This argument describes an infinite process. It’s absurd to think our mind uses infinite process to form mental images, because infinite processes never end – we’d never get anything done!

This argument is hard to think about. Let that go. It’s not your job to question the truth of premises. You must instead look for structure, and match it.

1. One thing requires a second thing.
2. The second thing requires another thing.
3. This goes on forever.

In practice, you should simply look through the answers for a process that continues forever. Only the correct answer has such a process.

___________

1. This answer doesn’t describe an infinite process. Also note that this answer says “highly unlikely”, while the stimulus said “cannot be correct.”
2. This answer has the word infinite, but this answer describes an infinite number of theories. The stimulus described an infinite process. Those are different. For instance, an infinite process keeps going forever, referring back to itself. An infinite number of wrong theories already exist.
3. CORRECT. This answer describes an infinite process. Since no theory is new, every theory must have a similar theory that preceded it. This can’t happen – obviously at some point a human thought up the first theory. So this infinite process is impossible, just like in the stimulus.
4. This answer has the word absurd, just like the stimulus. But you have to look at what “absurd” refers to. There is no infinite process here – the definition of “foundation” is simply wrong.
5. There’s no claim of infinity here. This is just a factual argument that shows that some libraries existed before the library at Alexandria.

Recap: The question begins with “Some philosophers explain visual perception by “. It is a Parallel Reasoning question. To practice more Parallel Reasoning questions, have a look at the LSAT Questions by Type page.