LSAT 148 – Section 3 – Question 18

LSAT 148 - Section 3 - Question 18

December 2016

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT148 S3 Q18
+LR
+Exp
Flaw or descriptive weakening +Flaw
Causal Reasoning +CausR
Sampling +Smpl
A
1%
151
B
3%
155
C
11%
158
D
4%
153
E
82%
164
140
149
157
 +Medium 149.233 +SubsectionMedium

Journalist: Scientists took blood samples from two large, diverse groups of volunteers. All the volunteers in one group reported that they enjoyed eating vegetables, whereas all those in the other group disliked vegetables. When the blood samples from the group that disliked vegetables were analyzed, it was discovered that all the volunteers in that group had a gene in common, the XRV2G gene. This strongly suggests that a dislike of vegetables is, at least in some cases, genetically determined.

Summarize Argument: Phenomenon-Hypothesis
The author concludes that a dislike of vegetables is sometimes caused by genetics. This is based on a study involving two large, divers groups of volunteers. Everyone in one group enjoyed eating vegetables, while everyone in the other group disliked vegetables. Everyone in the group that disliked vegetables had the XRV2G gene.

Identify and Describe Flaw
The author assumes that the group that liked vegetables did not all have the XRV2G gene. This is the basis of another assumption that the study revealed a correlation between not liking vegetables and having the gene. Then, the author makes another assumption that the explanation for this correlation is that the gene causes a dislike of vegetables.

A
It presumes that all human traits are genetically determined.
The argument concerns only the human trait of disliking vegetables. The author doesn’t make any assumptions about all other human traits.
B
It overlooks the possibility that the volunteers in one or both of the two groups may not have been representative of the human population as a whole in one or more respects.
The argument doesn’t generalize from the members of the study to the human population generally. The conclusion is just that a dislike of vegetables is sometimes genetically determined; those times could involve just members of the study.
C
It overlooks the possibility that even when one phenomenon always produces another phenomenon, the latter phenomenon may often be present when the former is absent.
The conclusion does not assert that a dislike of vegetables is only caused by genetics. The conclusion is merely asserting that a dislike of vegetables is sometimes caused by genetics. This acknowledges that such dislike can also be caused by other things besides genes.
D
It overlooks the possibility that even if a dislike of vegetables is genetically determined, it may be strongly influenced by genes other than the XRV2G gene.
This possibility doesn’t undermine the argument. If dislike of vegetables can also be caused by other genes, that supports the conclusion that a dislike of vegetables is at least sometimes genetically determined.
E
It takes for granted that the volunteers in the group that enjoyed eating vegetables did not also all have the XRV2G gene in common.
This must be assumed, because if it wasn’t true, the conclusion wouldn’t follow from the premises. If the group that liked vegetables also all had the XRV2G gene, then there’s no reason to think from the study that the XRV2G gene plays any role in dislike of vegetables.

Very similar to the weakness in this argument:
LSAT41-S1-Q12

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Section 1 - Logical Reasoning

Section 2 - Reading Comprehension

Section 3 - Logical Reasoning

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