LSAT 131 – Section 1 – Question 15

LSAT 131 - Section 1 - Question 15

December 2009

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT131 S1 Q15
+LR
+Exp
Flaw or descriptive weakening +Flaw
Eliminating Options +ElimOpt
A
2%
160
B
5%
158
C
49%
168
D
43%
162
E
0%
153
157
165
174
 +Hardest 147.383 +SubsectionMedium

The typological theory of species classification, which has few adherents today, distinguishes species solely on the basis of observable physical characteristics, such as plumage color, adult size, or dental structure. However, there are many so-called “sibling species,” which are indistinguishable on the basis of their appearance but cannot interbreed and thus, according to the mainstream biological theory of species classification, are separate species. Since the typological theory does not count sibling species as separate species, it is unacceptable.

Summarize Argument
The author concludes that the typological theory of species classification is unacceptable. This is based on the fact that (1) it doesn’t count sibling species as separate species, and (2) mainstream biological theory of species classification would classify sibling species as separate species.

Identify and Describe Flaw
The author assumes that the way mainstream biological theory classifies sibling species is the appropriate way to classify them. But we are presented with no reason to think that the mainstream theory’s approach is better than the typological theory’s approach.

A
the argument does not evaluate all aspects of the typological theory
The argument didn’t have to evaluate “all” aspects of typological theory. We’re allowed to criticize a single aspect. And if our criticism is valid, we’re allowed to reject a theory on the basis of that criticism.
B
the argument confuses a necessary condition for species distinction with a sufficient condition for species distinction
The author doesn’t confuse sufficient and necessary conditions. Nothing in the argument is based on a mistaken interpretation of a conditional relationship.
C
the argument, in its attempt to refute one theory of species classification, presupposes the truth of an opposing theory
The author tries to refute typological theory because it doesn’t treat sibling species as distinct species. But this would be a wrong classification only if we assume the mainstream classification is correct. So, the author assumes that the mainstream theory is true.
D
the argument takes a single fact that is incompatible with a theory as enough to show that theory to be false
There is no “fact” that is incompatible with typological theory. What is incompatible is another theory’s interpretation of sibling species as distinct species. The view that sibling species are distinct species is not a “fact.”
E
the argument does not explain why sibling species cannot interbreed
The argument does not need to explain why they can’t interbreed. The issue is whether species that look the same, but can’t interbreed, should be classified as different species. Mainstream theory says they should, and the author assumes that this is correct.

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LSAT PrepTest 131 Explanations

Section 1 - Logical Reasoning

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Reading Comprehension

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