PrepTest 123

[lcid:3590] Prep Test 123 LSAT — Logical Reasoning — S3 Logical reasoning

Question prompt

Naturalist:  The recent claims that 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.

Argument or Facts

Argument

Valid or Flawed

Flawed

Question Type

Strengthen with Necessary Premise Questions

Stimulus Summary

Sheep farming eliminated the Tasmanian tiger from its natural habitat, and since then naturalists working in the region have found no evidence of any Tasmanian tigers. Therefore, the Tasmanian tiger is extinct.

Answer Anticipation

The first trick to this question is to unpack the double negative in the conclusion. When an argument states that a claim is false, we should rephrase it to represent what the argument is actually stating. Here, saying that claims the tiger aren't extinct are false is equivalent to saying that the tiger is extinct.
With that straightened up, we can look for the error in the reasoning. The Naturalist is basing the claim that these tigers are extinct on their being eliminated from a region at a certain time. Additionally, naturalists have found no evidence of them in that region.
One error in that reasoning is that a lack of evidence of their existence doesn't prove they're extinct. While it would be justified to conclude that it's very likely they're extinct, a lack of evidence doesn't definitively prove they're gone. However, that's not the only flaw. On top of that, the evidence is all coming from this one region that's the tiger's natural habitat. There's no evidence that the tigers didn't move elsewhere, but the argument relies on that being true. Either of these flaws could result in a correct answer, so we should be on the lookout for answers that deal with either.

Answer choices

  1. A
    Sheep farming drove the Remaining source text redacted.
    Why choice A is not credited
    Incorrect. This answer choice is too specific. While the stimulus does rely on all the Tasmanian tigers dying out, it doesn't require them to have done so because of starvation.
  2. B
    Some scavengers in Tasmania Remaining source text redacted.
    Why choice B is not credited
    Incorrect. If anything, this answer choice weakens the argument. One explanation for the lack of carcasses is that the tiger went extinct. However, this answer proposes an alternative explanation—predators are getting rid of the carcasses—which would allow the tigers to not be extinct despite a lack of evidence of their presence. Since this answer provides an alternative explanation to that of the stimulus, it can't be necessary for the argument.
  3. C
    Every naturalist working in Remaining source text redacted.
    Why choice C is not credited
    Incorrect. This answer choice is too strong. While the argument does rely on naturalists not finding evidence of the tigers to conclude they went extinct, it doesn't require every naturalist to be systematically looking for evidence—just enough of them looking hard enough that they would find evidence if it existed.
  4. D
    The Tasmanian tiger did Remaining source text redacted.
    Why choice D matches the stem
    Correct. This answer choice addresses the flaw in the argument on where there has been a search for evidence. If the tigers did move to another region, then of course there would be no evidence of them in the region they were kicked out of by sheep. This answer choice eliminates an alternative possibility to them going extinct, and it is thus something the argument depends on.
  5. E
    Those who have reported Remaining source text redacted.
    Why choice E is not credited
    Incorrect. Even if some of the experienced naturalists reported seeing these tigers, they could still be wrong, and the tiger could still be extinct.

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