LSAT 145 – Section 4 – Question 20

LSAT 145 - Section 4 - Question 20

December 2015

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT145 S4 Q20
+LR
Sufficient assumption +SA
Conditional Reasoning +CondR
Link Assumption +LinkA
A
18%
163
B
42%
168
C
19%
162
D
7%
160
E
15%
160
159
168
177
 +Hardest 148.528 +SubsectionMedium

Live Commentary

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Selena claims to have psychic powers. So if we find out whether Selena’s claim is true, we will thereby determine whether it is possible to have psychic powers.

Summary
The author’s conclusion means the following:
If we find out that Selena does have psychic powers, then we will determine that it’s possible to have psychic powers. And, if we find out that Selena does NOT have psychic powers, then we will determine that it’s NOT possible to have psychic powers.
This conclusion is based on nothing more than the fact that Selena claims to have psychic powers.

Missing Connection
If Selena has psychic powers, then it’s inherently true that having psychic powers is possible.
But if Selena doesn’t have psychic powers, that doesn’t necessarily prove that it’s impossible to have psychic powers. After all, what if someone else besides Selena could have psychic powers.
So to make the argument valid, we want to establish that if Selena doesn’t have psychic powers, it’s impossible to have psychic powers. In other words, we want to know that nobody else can have psychic powers if Selena doesn’t have them.

A
No one else has yet been found to have psychic powers.
(A) doesn’t establish that if Selena doesn’t have psychic powers, no one else can have them. Sure, no one else has “yet been found” to have them. But that doesn’t mean it’s impossible for others to have psychic powers.
B
If it is possible to have psychic powers, then Selena has them.
(B) establishes that if Selena doesn’t have psychic powers, then it’s impossible to have psychic powers (think about the contrapositive of this answer). This supplies the missing piece of the argument; if we find out Selena’s claim is not true, we can determine that it’s not possible to have psychic powers.
C
It is possible to determine whether Selena has psychic powers.
Whether it’s possible to determine that Selena’s claim is true/false has nothing to do with what happens IF we find out her claim is true/false. Adding (C) to the argument still leaves us not knowing whether other people besides Selena can have psychic powers.
D
If Selena’s claim turns out to be false, we will not know whether it is possible to have psychic powers.
We want to prove that by finding out whether Selena’s claim is true, we WILL determine whether it’s possible to have psychic powers. In other words, we’ll find out that it’s possible or that it’s impossible. (D) is directed toward proving that we “will not know whether it is possible” to have psychic powers. Not knowing whether it’s possible is the opposite of what we want to establish.
E
We will not be able to determine whether it is possible to have psychic powers unless we find out whether Selena’s claim is true.
(E) simply reverses the conclusion. (E) establishes that finding out whether Selena has psychic powers is necessary to determine whether it’s possible to have psychic powers. But we want to establish that it’s sufficient to determine whether it’s possible to have psychic powers.

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LSAT PrepTest 145 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Reading Comprehension

Section 4 - Logical Reasoning

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