PrepTest 101

[lcid:3501] Prep Test 101 LSAT — Logical Reasoning — S2 Logical reasoning

Question prompt

The authors of a Remaining source text redacted.
Why the credited answer is right

Credited answer: A

The notes below walk through why it fits the stem and how to eliminate the rest.

Argument or Facts

Argument

Valid or Flawed

Flawed

Question Type

Argument Evaluation Questions

Stimulus Summary

Recent article: There’s no evidence the rate of extinction of animal species is speeding up
Author: More North American fish species went extinct in the second half of the 20th century compared to the first, so there is evidence of a faster extinction rate.

Answer Anticipation

When dealing with a question asking about the logic of an argument in a stimulus with multiple viewpoints, always be sure to split up the arguments to make it easier to analyze!
Here, the author’s argument is that a certain subset of fish saw an accelerating rate of extinction, so there is evidence that all animals are seeing such an increased rate of extinction. That’s basing a broad conclusion on a limited sample/single example, which assumes that the example raised is representative of the overall trend.
So in evaluating this argument, it would be helpful to know if the pattern seen in North American fish species is representative of the extinction pattern seen in other animals. Let’s find an answer asking that question.

Answer choices

  1. A
    Were the fish species Remaining source text redacted.
    Why choice A matches the stem
    A bit of a flip of what we expected! However, this question gets us the exact same information as the positive version of the question. Knowing whether or not the fish species examined are representative of animals overall as far as the pace of extinction is concerned would help us analyze this argument that generalizes from the fish to all animals. This answer is therefore correct.

  2. B
    How numerous were the Remaining source text redacted.
    Why choice B is not credited
    There’s no indication that the starting population size is related to the rate/threat of extinction - it could be environmental changes that kill off a species, and thus it wouldn’t matter if there were more or fewer to start with.

  3. C
    Did any of the Remaining source text redacted.
    Why choice C is not credited
    The author does rely on a subset of fish species, but she could have easily picked any subset of animals that saw an accelerating rate of extinction. Whether they were North American or moved there is out of scope, so this answer is wrong.

  4. D
    What proportion of North Remaining source text redacted.
    Why choice D is not credited
    Even if some species ended up turning it around over the period when others went extinct, that wouldn’t affect the argument. The argument is just about extinction, so what is true of the remaining animals is out of scope.

  5. E
    Were any of the Remaining source text redacted.
    Why choice E is not credited
    The commercial importance of these species may speak to whether the rate of extinction should be addressed for economic reasons, but it doesn’t speak to whether it’s happening in the first place. This answer is thus out of scope.

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