LSAT 142 – Section 4 – Question 18

LSAT 142 - Section 4 - Question 18

December 2014

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Question QuickView	Type	Tags	Answer Choices	Curve	Question Difficulty	Psg/Game/S Difficulty	Explanation
PT142 S4 Q18	+LR	Flaw or descriptive weakening +Flaw Causal Reasoning +CausR Sampling +Smpl	A 7% 159 B 15% 160 C 1% 158 D 38% 163 E 40% 167	157 169 180	+Hardest	147.564 +SubsectionMedium

Pharmacist: A large study of people aged 65–81 and suffering from insomnia showed that most of insomnia’s symptoms are substantially alleviated by ingesting melatonin, a hormone produced by the pineal gland, which plays a role in the regulation of the body’s biological clock. Thus, the recent claims made by manufacturers of melatonin supplements that the pineal gland produces less melatonin as it ages are evidently correct.

Summarize Argument

The author concludes that the pineal gland produces less melatonin as it ages. This is based on a study of people aged 65-81 suffering from insomnia. The study showed that most insomnia symptoms in these people are reduced by eating melatonin. Melatonin is a hormone produced by the pineal gland, and it has a role in regulating the body’s biological block.

Identify and Describe Flaw

The author assumes that the melatonin of people in the study is lower than those levels would have been when those people were younger. The author also assumes that people in the study, who all have insomnia, are representative of people generally with respect to melatonin at the corresponding age (65-81). This overlooks the possibility that the study’s subjects have unusually low melatonin (which might be why they have insomnia). An average person might not have low insomnia at 65-81.

infers from the effect of an action that the action is intended to produce that effect

The author does not make any assumptions about intentions. Whether people take melatonin because they intended to reduce insomnia symptoms doesn’t matter. We know that eating melatonin did reduce symptoms in the study.

relies on the opinions of individuals who are likely to be biased

The argument doesn’t rely on opinions to support the conclusion. The conclusion happens to refer to the claims of manufacturers, but this reference is not used as part of the reason to believe that the pineal gland produces less melatonin as it ages.

depends on using two different meanings for the same term to draw its conclusion

There is no term that is used in two different ways. “Insomnia,” “melatonin,” “pineal gland” all have consistent meanings.

confuses an effect of a phenomenon with its cause

It’s not clear what (D) refers to. In any case, we don’t know know from the premises that any causal relationship is reversed. Does lower melatonin cause insomnia, or is it reversed? We don’t know, so can’t say that the author is confusing an effect for a cause.

relies on a sample that is unrepresentative

The study only included people with insomnia, and only included people 65-81. We don’t know whether people with insomnia have unusually low melatonin for their age. And we don’t know whether the melatonin levels change by age, since the study didn’t evaluate younger people.

LSAT 142 – Section 4 – Question 18

LSAT 142 - Section 4 - Question 18

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LSAT PrepTest 142 Explanations

Section 1 - Logical Reasoning

Section 2 - Logical Reasoning

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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