PT105.S2.Q20

PrepTest 105 - Section 2 - Question 20

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Some people have been promoting a new herbal mixture as a remedy for the common cold. ███ ███████ █████████ █████ █████ ███████ ████████ ██ ███ ██████ ██████ ██████████ ███ ███████████ █ ████ █████████ █████████ ██ ███ █████ ████ ███ ███████ ██ ██ █████████ ████ ███████ ███████ ████████ ████ ███ ███████ ████ ██ █████████ ████ ███████ █████ ████ ██████ ████ █████ ████ ██ ███████ ████████ ██ ███████ ████ ██████ █████████ ████ █ ████ █████ ██ █████ ███ ██████████ █████ █████ ███ ████ ██████ ███ ████ █████ ███ ██ ███ ███ ███ ████████ ██ ██ █████████ ███ ███████████

Argument Analysis: Counter-Position

The stimulus introduces an herbal mixture that some people have been advocating as an effective cold remedy. We're interested in the argument one cold sufferer uses to reject the claim that this remedy is effective. According to the cold sufferer, if this claim were true — i.e., if this mixture were actually effective — then most people with colds would be using it, since most people with colds want to recover quickly. But the cold sufferer points out that in fact, many people with colds don't use the mixture Therefore, the cold sufferer concludes, the mixture must not be an effective remedy.

Let's dig into the cold sufferer's argument, which is what questions 20 and 21 focus on. To counter the claim that this cold remedy is effective, the cold sufferer sets up an argument involving conditional logic. He gives us the premise that most people with colds want to recover quickly. This idea is never disputed: it's taken as a "given" or a preliminary for the conditional argument that follows, but it's not itself one of the conditions in that argument.

The actual conditional argument runs like this: if this mixture were effective (a sufficient condition), almost all people with colds would be using it (a necessary condition). Since many people with colds are not using it (supposedly, the negation of the necessary condition), the mixture must not be effective (negation of the original sufficient condition). Basically, the cold sufferer is trying to make an argument using the logic of the contrapositive: if A, then B; but since /B, we have to conclude /A.

It's important to see that this argument is flawed. Saying that "many" people don't use the mixture isn't necessarily a negation of the statement "almost all people with colds use the mixture". Remember that "many" on the LSAT is an indefinite quantity similar to "some". The argument also relies on the assumption that people who want to recover from colds quickly would know that this mixture is effective. If they didn't know, then it wouldn't necessarily be true that they would nearly all be using it, even if it were effective.

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20.

Each of the following is ██ ██████████ ████████ ██ ███ █████████ ████ ██████████ ████████ ███████

a

Enough of the ███████ ██ ████████ ██ ███████ ███ ████████ █████ ██ ██████ █████████ ████ █ █████
If we negate (A), we get: "Not enough of the mixture is produced to provide the required doses to almost everybody with a cold." This would give us another reason that many people with colds aren't using the mixture: it's not necessarily that the mixture isn't effective, there just isn't enough of it for everyone. Since negating (A) destroys the argument, (A) is a necessary assumption and not the answer choice we're looking for.
3%
b

The mixture does ███ ████ ████ ███████ ██████ ██████ ██ ████ ████ ██████ ███ ████ █████ █████ █████ ███
If we negate (B), we get: "The mixture does have side effects severe enough to make many people who have colds avoid using it." This would undermine the cold sufferer's argument, because it would suggest that the reason many people with colds don't use the mixture is that they are afraid of its side effects, not that the mixture isn't effective in treating colds. So (B) isn't what we're looking for either.
4%
c

The mixture is ████████ ██████ ██ ███████ ██████ █████████ ███ ████ ██ ████ ███████████ ███ ███████ ██████
Correct. Remember that the cold sufferer is arguing that the cold mixture is not effective, not that it is so effective that it even prevents further colds. Far from being a necessary assumption of the cold sufferer's argument, (C) actually contradicts the cold sufferer's argument. This is the answer choice we're looking for.
80%
d

The mixture is ██████ ██████ █████ ████ ██████ █████████ ████ █ ████ ██ █████ ██ ███
This is one of the assumptions we identified in our analysis. If (D) is false, and the mixture is not widely enough known that almost everybody with a cold is aware of it, then the reason many people with colds don't use it might not be that the mixture isn't effective. Those people might just have never heard of it. (D) is a necessary assumption, and so isn't the answer choice we're looking for.
4%
e

There are no █████████ ████ ████████ █████████ ████ ████ ██████ ███ ████ █████ ██████ ██ ███ ████████
If we negate (E), we get: "There are at least some effective cold remedies available that many people who have colds prefer to the mixture." In other words, the reason many people with colds don't use this mixture might not be that this mixture isn't effective: there might just be other remedies that are also effective, which those people prefer. So (E) is a necessary assumption, and isn't the answer choice we want.
9%

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