LSAT 139 – Section 1 – Question 24

LSAT 139 - Section 1 - Question 24

June 2013

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT139 S1 Q24
+LR
Flaw or descriptive weakening +Flaw
Causal Reasoning +CausR
Sampling +Smpl
A
1%
155
B
2%
153
C
83%
165
D
5%
157
E
10%
163
136
147
159
 +Medium 142.273 +SubsectionEasier

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In an effort to reduce underage drinking, the Department of Health has been encouraging adolescents to take a pledge not to drink alcohol until they reach the legal age. This seems to be successful. A survey of seventeen-year-olds has found that many who do not drink report having taken a pledge to refrain from drinking, whereas almost all who drink report having never taken such a pledge.

Summarize Argument
The author argues that there’s reason to believe that the government’s plan to reduce underage drinking by having adolescents take a pledge has been successful. This is because a survey of teenagers found that a number of non-drinkers took the pledge, whereas most drinkers didn’t.

Identify and Describe Flaw
This is a correlation-causation fallacy. The argument takes a weak correlation (the fact that some non-drinkers have taken the pledge) and attempts to use it as evidence that the pledge causes people to not drink. This is particularly weak because it’s likely tainted by selection bias, since people who already abstain from drinking would probably be more likely to take the pledge. Moreover, we don’t even know how strong the correlation is because “many who do not drink” is too vague to determine the pledge’s success rate.

A
bases a conclusion about the efficacy of a method to reduce underage drinking merely on a normative judgment about the morality of underage drinking
This would describe a premise like “drinking is wrong”, but the argument uses a correlation as support instead. The problem is assuming that this correlation establishes a causal link.
B
fails to consider that an alternative method of reducing underage drinking might be more effective
This is irrelevant because the conclusion is simply that this effort seems to be successful. It doesn’t matter if another method could be more successful.
C
infers from an association between pledging not to drink and refraining from drinking that the pledging was the cause of refraining from drinking
This describes the causation-correlation fallacy found in the argument. The premise only establishes a weak correlation between those who take the pledge and those who abstain from drinking, but assumes that this means the pledge is what’s causing people not to drink.
D
treats a condition that is sufficient to produce an outcome as though it were necessary for the outcome to occur
The argument doesn’t employ conditional reasoning to reach its conclusion. The conclusion identifies a supposed causal relationship, but is flawed because it only cites a weak correlation as support.
E
confuses the claim that many adolescents who do not drink report having taken the pledge with the claim that many who report having taken the pledge do not drink
These two claims are logically equivalent, so this doesn’t speak to the argument’s flaw. The argument’s problem is citing a weak correlation as evidence for a causal relationship.

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LSAT PrepTest 139 Explanations

Section 1 - Logical Reasoning

Section 2 - Reading Comprehension

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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