LSAT 137 – Section 2 – Question 20

LSAT 137 - Section 2 - Question 20

October 2012

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT137 S2 Q20
+LR
Argument part +AP
Causal Reasoning +CausR
A
7%
159
B
2%
153
C
68%
165
D
9%
158
E
13%
160
147
156
165
 +Harder 146.731 +SubsectionMedium

Astronomer: Earth was bombarded repeatedly by comets and asteroids early in its history. This bombardment probably sterilized the surface and prevented life from originating during this early period in Earth’s geological history. Meanwhile, Mars escaped severe bombardment, and so there could have been microbial life on Mars prior to there being such life on Earth. Because many meteorites originating from Mars have landed on Earth, life on Earth may have started when living microbes were carried here from Mars on a meteorite.

Summarize Argument
The astronomer concludes that life on Earth might’ve started with a microbe-carrying meteorite from Mars. While Earth was rendered inhospitable to early life by asteroid strikes, Mars escaped such strikes and therefore could’ve fostered life early in its history. And many meteorites originating on Mars have ended up striking Earth.

Identify Argument Part
The referenced text helps explain how life on Earth could’ve started with a meteorite from Mars. If Mars actually wasn’t able to generate microbial life before Earth was, then there would be no reason to believe the meteorite argument. So, the astronomer makes sure to tell us that Mars could’ve hosted microbial life.

A
It is a claim for which no justification is provided but that is required in order to establish the argument’s main conclusion.
The reference text is justified by the claim that Mars escaped asteroid bombardment early in its history. It’s a reason why Mars might’ve been able to host microbial life even when Earth couldn’t.
B
It is a claim for which no justification is provided and that, if true, ensures the truth of the argument’s main conclusion.
The reference text is justified by the claim that Mars escaped asteroid bombardment early in its history. It certainly doesn’t ensure the truth of the argument’s conclusion, as there could be other factors that limit this meteorite-strike theory.
C
It is a claim for which some justification is provided and that is required in order to establish the argument’s main conclusion.
The claim is certainly justified—Mars wasn’t bombarded by asteroids like Earth was. It’s also required to establish the conclusion. If Mars couldn’t have hosted microbial life before Earth, then the meteorite-strike theory falls apart.
D
It is a claim for which justification is provided and that, if true, establishes the truth of the argument’s main conclusion.
The claim, while justified, doesn’t establish the truth of the argument’s main conclusion. There could be other reasons why the meteorite-strike theory is problematic.
E
It is a claim that provides some support for the argument’s conclusion but that neither ensures the truth of that conclusion nor is required in order to establish that conclusion.
The referenced text supports the conclusion, and is indeed necessary to establish that conclusion. If Mars couldn’t have hosted microbial life before Earth, how could the meteorite-strike theory make any sense?

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LSAT PrepTest 137 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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