Logical reasoning PrepTest 105 · Section 2 · Question 4

Question prompt

An ingredient in marijuana Remaining source text redacted.
Why the credited answer is right

Credited answer: B

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

Weaken Questions

Stimulus Summary

THC inactivates herpesviruses, which can cause cancer, so marijuana can cause cancer.

Answer Anticipation

This is a great question to highlight one nuance on the LSAT. In Weaken questions, we frequently get Correlation/Causation flaws, and this argument has causation all over it - including in the conclusion. However, the premises are also causal, and causal premises can support a causal conclusion, so there isn’t a Correlation/Causation flaw here. However, if we trace the causal chain, we can see that the premises establish that THC - one ingredient in marijuana - can be a causal factor in cancer (by deactivating herpesviruses). However, that doesn’t mean that marijuana causes cancer - that’s taking a characteristic of the part and assigning it to the whole. Maybe marijuana, when all things are considered, has something else in it that balances out the carcinogenic properties of THC. Anything that suggests marijauana as a whole doesn’t have the same carcinogenic properties as one ingredient in it will serve to weaken this argument.

Answer choices

  1. A
    Several teams of scientists Remaining source text redacted.
    Why choice A is not credited
    More experiments that agree with the same result serve to strengthen an argument.
  2. B
    The carcinogenic effect of Remaining source text redacted.
    Why choice B matches the stem
    This answer establishes that other ingredients in marijuana might counteract the carcinogenic effect of THC, and so marijuana might not cause cancer. This answer calls into question the conclusion, so it’s correct.
  3. C
    When THC kills herpes Remaining source text redacted.
    Why choice C is not credited
    First, this answer doesn’t address marijuana as a whole. Second, it provides even more reasons to believe that at least one ingredient of marijuana causes cancer, which aligns with the argument.
  4. D
    If chemists modify the Remaining source text redacted.
    Why choice D is not credited
    What could be true if something is done doesn’t speak to what is true of THC-containing marijuana.
  5. E
    To lessen the undesirable Remaining source text redacted.
    Why choice E is not credited
    By removing a part of the causal chain, this answer brings itself out of scope since it’s applying to people for whom the herpesvirus step doesn’t apply.

What this tests

Question analytics

Based on historical answer selection rates for this question.

Answer choice distribution

  1. A 3%
  2. B Credited 71%
  3. C 13%
  4. D 3%
  5. E 11%

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Discussion

  • Choice A 2 replies

    Started by Meredith

  • Explain answer 1 reply

    Started by TheFacu

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