PrepTest 106

[lcid:3522] Prep Test 106 LSAT — Logical Reasoning — S3 Logical reasoning

Question prompt

The interstitial nucleus, a 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.

Argument or Facts

Argument

Valid or Flawed

Flawed

Question Type

Cause & Effect / Weaken Questions

Stimulus Summary

Male cats who die from disease X have a larger IN than other male cats, so the size of the IN is a factor in male cats getting disease X.

Answer Anticipation

When we’re dealing with a Weaken question, it’s likely that we’ll end up with a Correlation/Causation flaw. We should generally start by seeing if that’s present!
Here, a neurobiologist found that an enlarged IN was correlated with male cats dying of disease X, and she concludes that the size of the IN is a factor in determining whether male cats can get disease X. That’s a jump from correlation to causation, so we can look for one of our normal answers:
Identify an alternative cause Counterexamples (cause without effect; effect without cause) Reverse causality (disease X causing the IN to enlarge)

Answer choices

  1. A
    No female cats have Remaining source text redacted.
    Why choice A is not credited
    We know that male and female cats are physiologically different (the female cats have a larger IN), so this answer about female cats doesn’t necessarily tell us anything about male cats.
  2. B
    Many male cats who Remaining source text redacted.
    Why choice B is not credited
    Tempting! It can seem as if this presents an alternative cause in disease Z. However, there are two problems here. First, this talks about “[m]any” male cats with disease X also getting disease Z. That’s a weaker correlation than that between disease X and an enlarged IN, which was found in all cats with X. Second, nothing is known about the cause of Z, which means that disease X might itself be a cause! This answer is too weak to have an impact on the argument.
  3. C
    The interstitial nuclei of Remaining source text redacted.
    Why choice C is not credited
    Ignoring that this answer is about female cats (see answer (A)), it also would, if anything, strengthen the argument by showing another example of the cause (enlarged IN) going along with the effect (disease X).
  4. D
    Of 1,000 autopsies on Remaining source text redacted.
    Why choice D is not credited
    An average allows for some variance, so the 5 who had INs larger than average may have been well within the size that is considered normal. The stimulus specifically notes that the cats in question had INs the size of female cats, which may be much larger than these 5 cats who were just “larger than...average.”
  5. E
    The hypothalamus is known Remaining source text redacted.
    Why choice E matches the stem
    Wow, this answer more or less states that the hypothalamus (which includes the IN) isn’t a causal factor in disease X, directly undermining the argument’s conclusion. While it’s rare to have such a direct weakener, this one certainly does so!

What this tests

Discussion

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