LSAT 69, Logical Reasoning II, Q22, LSATHacks

LR Question 22 Explanation, by LSATHacks

QUESTION TEXT: If the magazine's circulation continues to rise as it…

QUESTION TYPE: Flawed Reasoning

CONCLUSION: The magazine won’t be the largest selling martial arts magazine in ten years.

REASONING: If circulation keeps rising, the magazine will be the best selling martial arts magazine. But circulation won’t keep rising.

ANALYSIS: This sounds like a good argument, but really it just incorrectly negates a conditional statement. We have:

Rising fast ➞ Best seller

The argument incorrectly assumes:

Rising fast ➞ Best seller

It’s possible the magazine will be the best selling magazine in ten years even if sales stop rising. Maybe the magazine is already the best seller. Maybe other magazines will see circulation drop.

___________

1. This is a different error. The author doesn’t have to prove that the changes are the only necessary condition. They just have to prove that the changes are a necessary condition. Failing to meet any necessary condition will negate a sufficient condition.
2. The argument doesn’t say that slower growth will cause circulation to shrink. The author only says that the magazine will not be a best seller if growth slows.
3. The argument didn’t use circular reasoning.
   They have some evidence for the conclusion: circulation won’t increase at the same rate.
4. Actually, a single fact incompatible with a general claim is always enough to prove a general claim false. If I say ‘all swans are white’, then you just need to find one black swan to prove the statement wrong.
5. CORRECT. A continued rise in circulation will ensure that the magazine is the best seller.
   But the rise in circulation may not be necessary. Maybe the magazine is already the best seller. Maybe other magazines’ circulation will shrink.

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