Tuesday, December 17, 2013

LSAT Logical Reasoning: Flaw

Question Type: Flaw
These questions ask you to identify an error of reasoning in the stimulus argument.
Some sample question stems are
1. Which one of the following, if true, identifies a flaw in the plan for the program?
2. The argument is vulnerable to criticism on the grounds that the argument
3. The reasoning above is questionable because it fails to exclude the
possibility that
4. The reasoning in the politician’s argument is flawed because this argument
5. Ralph’s reasoning in his response to Jessica is most vulnerable to criticism on the
grounds that it
6. Which one of the following is a questionable argumentative strategy employed
in the above argument?
Strategies
The question stem tells you that a problem exists with the logic of the argument. You
just have to choose the answer that describes the flaw. Most flawed arguments include
an unwarranted assumption; in other words, the argument is weakened by a missing link
between the stated evidence and the stated conclusion. The author of the argument is
taking something for granted that is not necessarily true.
Sample Flaw Question
Consider the following example:

1. Giant Motors is attempting to dominate the automobile market by promoting its
products with an expensive television advertising campaign. But, the results of recent
surveys reveal that, in the opinion of 85 percent of all consumers, Giant Motors
already dominates the market. Since any product with more than half of all sales in
any given market is already dominant, Giant Motors dominates the market now and
must only preserve its market share in order to continue to dominate its market.
The argument commits which one of the following errors in reasoning?
(A) Failing to eliminate the possibility that what seems to be the outcome of a
specific market condition might actually be the cause of the condition
(B) Confusing a condition necessary for certain outcome to obtain for a condition
that, alone, is sufficient to assure that result
(C) Treating the failure to establish the falsity of a specific claim as tantamount
to showing that such a claim is certainly accurate
(D) Accepting evidence that a claim is believed to be true as evidence that the
claim, itself, is actually true
(E) Describing the results of a survey that was done in the past as acceptably
predicting future conditions
The best answer is D. The survey results only show the opinions of consumers. The
stimulus argument relies upon those beliefs as fact in concluding that Giant Motors
dominates the automobile market. There is no reason to accept the opinion of
consumers as an accurate measure of Giant Motors’s actual share of the automobile
market. Each of the other answer choices describes an error in reasoning that is irrelevant
to the stimulus argument.

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