Section Types Logical Reasoning

LSAT 71 - Section 3 - Question 18

January 19, 2014

An additional note to (D)

The reasoning Quick Silver gave below is correct. The bigger flaw in the argument is that they were surveying people who already bought video conferencing equipment. If they already bought video conferencing equipment, then presumably they needed video conferencing equipment. That's like saying most people could use a nice new set of golf clubs because we survey people who already owned golf clubs and they said it was a great purchase.

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LSAT 71 - Section 3 - Question 19

January 19, 2014

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LSAT 71 - Section 3 - Question 20

January 19, 2014

19 comments

LSAT 71 - Section 3 - Question 21

January 19, 2014

29 comments

LSAT 71 - Section 3 - Question 22

January 19, 2014

43 comments

LSAT 71 - Section 3 - Question 23

January 19, 2014

28 comments

LSAT 71 - Section 3 - Question 24

January 19, 2014

1 comment

LSAT 71 - Section 3 - Question 25

January 19, 2014

30 comments

LSAT 71 - Section 3 - Question 26

January 19, 2014

27 comments

LSAT 140 - Section 3 - Question 18

January 19, 2014

A recent magazine article argued that most companies that do not already own videoconferencing equipment would be wasting their money if they purchased it. However, this is clearly not true. In a recent survey of businesses that have purchased such equipment, most of the respondents stated that the videoconferencing equipment was well worth its cost.

Summarize Argument: Counter-Position

The author concludes that the article is wrong. As support, she cites a recent survey of businesses that bought videoconferencing equipment; most respondents said it was worth the cost.

Identify and Describe Flaw

This is the cookie-cutter flaw of using an unrepresentative sample, where a conclusion about a group is based on a sample that is likely meaningfully different from the group.

There are two reasons that the sample could be meaningfully different from “most companies.”

(1) The survey only includes companies who have purchased the equipment. Presumably these companies needed the equipment. This doesn’t mean “most companies” wouldn’t be wasting their money; maybe most companies don’t need it.

(2) It’s possible that only companies that were happy with the equipment responded to the survey, so the “respondents” are even less reflective of the whole group.

A

concludes that something is worth its cost merely on the grounds that many businesses have purchased it

Her conclusion isn’t just based on the fact that many businesses have purchased the equipment, but on the fact that many of those businesses said the equipment was worth the cost.

B

takes a condition sufficient to justify purchasing costly equipment to be necessary in order for the cost of the purchase to be justified

This is the cookie-cutter flaw of confusing necessary and sufficient conditions. The author doesn’t make this mistake; she never presents a condition that is sufficient to justify purchasing the equipment. Instead, she uses an unrepresentative sample to support her conclusion.

C

rejects a position merely on the grounds that an inadequate argument has been given for it

This is the cookie-cutter flaw of assuming that a conclusion is false simply because the support for that conclusion is weak. The author doesn’t make this mistake. She rejects the article’s position, but she does provide evidence to support her claim.

D

relies on a sample that it is reasonable to suppose is unrepresentative of the group about which it draws its conclusion

The author relies on the survey’s respondents, which are probably not representative of “most companies.” Companies that bought the equipment likely needed it, while those that haven’t bought equipment may not.

E

confuses the cost of an item with its value to the purchaser

By arguing that most businesses would not be wasting their money by purchasing the equipment, the author is actually distinguishing between value and cost, not confusing them. She’s suggesting that, even though it’s expensive, the equipment will still have value to the companies.

An additional note to (D)

The reasoning Quick Silver gave below is correct. The bigger flaw in the argument is that they were surveying people who already bought video conferencing equipment. If they already bought video conferencing equipment, then presumably they needed video conferencing equipment. That's like saying most people could use a nice new set of golf clubs because we survey people who already owned golf clubs and they said it was a great purchase.

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