EP2620 wrote:
A researcher studying drug addicts found that, on average, they tend to manipulate other people a great deal more than nonaddicts do. The researcher concluded that people who frequently manipulate other people are likely to become addicts.
Which of the following, if true, most seriously weakens the researcher’s conclusion?
I'm posting an explanation because I struggled with options A, C and D, and while GMATNinja has pointed out the flaw in Option D, I wanted to confirm my learning from option A and C too
Gaps:
1) Manipulating more is not the same thing is manipulating more frequently
2) There seems to be a correlation between addiction and manipulation. It could be that addiction leads to manipulation and not the other way round
(A) After becoming addicted to drugs, drug addicts
learn to manipulate other people as a way of obtaining drugs.
Initially, I rejected this option thinking that it doesn't tell me what addicts do before becoming addicted - maybe these non-addicts are manipulative for different reasons. Basically, what I was thinking about was:
1. People learn to manipulate others
2. Become drug addicts
3. Learn to manipulate for a very specific cause The key lesson here was the presence of the word learn. 'Learning manipulation' would only happen once, its application, however, might change based on the stage of addiction. Hence, if my case were true, the verb in the sentence would have been use instead of learn.
1. People learn to manipulate others
2. Become drug addicts
3. Use manipulation tactics for a specific cause [b]GMATNinja : Could you please tell me if my understanding is correct?[/b] What if option A were: 'After becoming addicted, people
use manipulation tactics to obtain drugs' - in that case,
would this option weaken our conclusion that manipulation is more likely to lead to addiction?(C) Some non-addicts manipulate other people more than some addicts do.
We can have 3 categories of people:
i) Non-addicts who don't manipulate
ii) Non-addicts who manipulate
iii) Addicts who manipulate
This argument seems to be saying that x people in group (ii) are more manipulative (whatever that means) than y people in group iii
However, we were simply concerned with a comparison of people in group i) and group ii)
Hence, out of scope(D) People who are likely to become addicts exhibit unusual behavior patterns
other than frequent manipulation of other people
GMATNinja's explanation for this is perfect- patterns 'other than' could mean maybe they frequently manipulate, maybe they don't.Let's take a step back and look at the passage to get any clues we can from there before answering your questions.
We're told that the researcher's conclusion is:
that people who frequently manipulate other people are likely to become addicts
The evidence provided for this is that drug addicts tend to manipulate people
"a great deal more" than nonaddicts do.
The second gap you mention in your post is particularly important here -- there is a correlation between manipulative behavior and drug addiction. However, we have no information on whether one of them causes the other.
Let's look at (A) first:
Quote:
(A) After becoming addicted to drugs, drug addicts learn to manipulate other people as a way of obtaining drugs.
You're correct to have noticed the use of the word
learn but it's not enough to focus on that and not the rest of the answer choice. You should also be focusing on the word
after.
If the drug addicts did not learn to manipulate people until
after they had become addicted, then we
cannot say they were manipulative
before their addiction. It is possible that many drug addicts were not manipulative before becoming addicted but are manipulative now that they are addicted. This would point the causality in the opposite direction to the researcher's conclusion.
Therefore, it would
not be correct to say that manipulative people are more likely to become drug addicts. This is why (A) weakens the conclusion.
Before answering your next question, there's a caveat that you really don't benefit from changing the answer choices. You can only argue with what's been written in the question.
However, changing "learn" to "use" in (A) would
not weaken the answer choice. In this case, there is nothing to say these drug addicts did not use manipulation before they became addicts. This removes the possibility of the argument outlined above and, therefore, does not weaken the conclusion.
(C) says:
Quote:
(C) Some nonaddicts manipulate other people more than some addicts do.
We are not necessarily
only interested in the people in your group (i) and group (iii) -- the argument in the passage suggests people in group (ii) are more likely to become addicts than the people in group (i), so we shouldn't ignore them.
The passage says it's
more likely that manipulative people will
become addicts. There are two reasons why (C) does not weaken the conclusion.
First, the researcher's conclusion does not rely on
every manipulative person becoming an addict.
Some manipulative people can remain addiction-free and not weaken the researcher's conclusion. In the same vein, some addicts may not be manipulative at all -- so it would make sense that some nonaddicts are more manipulative than these addicts. This is enough to eliminate (C) but let's look at another reason.
The researcher's conclusion is that manipulative people are more likely to
become addicts. There's nothing in (C) to suggest that the nonaddicts mentioned won't become addicts themselves
eventually. These people are demonstrating the behavior the researcher is talking about, so the researcher thinks they are
more likely to become addicts, they are just not addicted
yet. It's not that (C) is out of scope, it's that (C) doesn't give us any reason to doubt that manipulative people are more likely to become addicts. This gives us the reasons we need to eliminate (C).
I hope that helps!