LSAT 154 – Section 4 – Question 26

LSAT 154 - Section 4 - Question 26

September 2017

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT154 S4 Q26
+LR
Sufficient assumption +SA
Conditional Reasoning +CondR
Link Assumption +LinkA
A
4%
158
B
9%
159
C
4%
158
D
78%
165
E
5%
156
138
149
161
 +Medium 147.301 +SubsectionMedium

Current evidence indicates that there is no methane on Planet 253. If that is the case, it is certain that there is no life on Planet 253. Since microbes always produce methane, if there is no methane then there are no microbes.

Summary
The author concludes that if there’s no methane on Planet 253, then there is no life on Planet 253. Why? Because if there is no methane, then there are no microbes.

Missing Connection
We know that if there’s no methane, there’s no microbes. But how does this imply that if there’s no methane, there’s no LIFE? “No life” is a new concept in the conclusion. So, at a minimum, the correct answer must tell us what is sufficient to lead to “no life,” or what is required in order to have “life.”
To go further, we can anticipate a more specific connection. We already know from the premise that “no methane” implies “no microbes.” To get to “no life,” we just want to establish that “no microbes” implies “no life.” In other words, that life requires microbes.

A
There is, in fact, no methane on Planet 253.
The conclusion is conditioned on the hypothetical that there is no methane on Planet 253. Whether this hypothetical is true doesn’t prove the conclusion, because the conclusion already presumes that it’s true for the purpose of the argument.
B
If methane exists on Planet 253 then we would be able to detect its presence.
(B) doesn’t establish what is sufficient to lead to “no life.” Since neither this answer nor the premises establish what leads to “no life,” (B) cannot make the argument valid.
C
If there is no methane currently on Planet 253 then there has never been methane on Planet 253.
(C) doesn’t establish what is sufficient to lead to “no life.” Since neither this answer nor the premises establish what leads to “no life,” (C) cannot make the argument valid.
D
If there are no microbes on Planet 253 then there is no life on Planet 253.
We know that if there’s no methane on Planet 253, there’s no microbes on Planet 253. According to (D), that allows us to conclude there is no life on Planet 253, if there’s no methane.
E
If there is methane on Planet 253 then there must be life on Planet 253.
(E) allows us to reach a conclusion that there IS life on Planet 253. But we want to establish that there is NO life on the planet. (E) is essentially a version of the conclusion that confuses sufficiency and necessity.

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LSAT PrepTest 154 Explanations

Section 1 - Logical Reasoning

Section 2 - Logical Reasoning

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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