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#26302
Complete Question Explanation

Weaken—CE. The correct answer choice is (B)

The study in the stimulus, like many studies on the LSAT, is highly questionable. The study shows that the group who inhaled the scent of peppermint had more difficulty falling asleep than the group who inhaled the scent of bitter orange. Assuming the study is properly conducted and controlled, there would be two reasons for the observed phenomenon: either peppermint makes it more difficult for people to fall asleep, or bitter orange makes it easier for them to do so. The author notes that bitter orange does not help people for asleep more easily. Having ruled out one possible cause, she concludes that the scent of peppermint is at the root of the discrepancy observed:
  • Cause ..... ..... ..... ..... ..... ..... ..... ..... ..... Effect

    Peppermint makes falling asleep difficult
    ..... ..... ..... ..... ..... ..... ..... ..... :arrow: ..... Peppermint group had more ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... difficulty falling asleep
    Bitter orange makes falling asleep easy

The problem with this argument, as with many causal arguments, is that there is not enough information in the premises to establish the causal relationship in the conclusion. There could be many other possible explanations besides the scent of peppermint that could have caused the peppermint group to have more difficulty falling asleep. Considering this argument is based on the results of a study, look for evidence suggesting that the study was not properly conducted.

Answer Choice (A): The conclusion in the stimulus is about the effect of peppermint on people who do suffer from insomnia. This answer choice discusses the effect of peppermint on people who do not suffer from insomnia. This answer choice is irrelevant to the argument in the stimulus.

Answer Choice (B): This is the correct answer choice. If the peppermint group suffered from more severe insomnia than the bitter orange group, this would suggest that the study was not properly controlled. Indeed, if the peppermint group had more severe insomnia all along, this could easily explain why they had more difficulty falling asleep. This is a classic example of an alternate cause, illustrating the importance of questioning the assumption implicit in many LSAT stimuli that the studies or surveys described are properly conducted.

Answer Choice (C): Even though the patients knew they were participating in a study, the study still shows a difference in the levels of insomnia between the two study groups. In light of the patients’ knowledge, the peppermint is no less likely to be the cause of this difference. Therefore, this answer choice does not weaken the argument.

Answer Choice (D): The insomnia discussed in the stimulus dealt with the effect these two substances had on falling asleep, not staying asleep. The fact that some of the study participants also had trouble staying asleep is irrelevant to this argument.

Answer Choice (E): If peppermint was known to be a pleasant scent, then this answer choice actually strengthens the argument because it increases the likelihood that peppermint has an effect on insomnia. However, the stimulus does not establish that peppermint is a pleasant scent, so this answer choice has no effect on the argument in the stimulus.

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