GMAT Critical Reasoning: Weaken Questions
Written by Kelly Granson.
Weaken questions are the most frequently occurring problem type on the GMAT Critical Reasoning section. They usually ask you to do a fairly simple thing: find an answer that will undermine the argument offered in the question stem. Weakening an argument is, however, not as straightforward as it may seem. The key to cracking the Weaken question is a very clear understanding of what exactly it is that we want to challenge when casting doubt on an argument. That is the focus of this article. You will learn how Weaken questions usually look, what information you should look for in the right choice, and what answers to avoid.
How to recognize a weaken question
A Weaken question can ask you to undermine, challenge, or cast doubt on the validity of an argument. In its most basic form, it will sound like this:Which of the following, if true, most seriously weakens the argument?
Sometimes, however, problems of this type might be formulated more obscurely. Consider the following questions:Which of the following, if true, most strongly supports the view that the company's new incentive program will not be successful?
Which of the following, if true, could be of the most use to the opponents of the new government policy?
These last two examples are both more specific and potentially more confusing. Despite positive-sounding language (most strongly supports, could be of the most use), they are still essentially Weaken questions, asking you to challenge the validity of a certain plan or policy.
How to analyze an argument
At the core of each typical Weaken question lies an argument; the author draws a conclusion based on stated premises. Weakening such an argument requires demonstrating that the author has failed to account for some circumstance or possibility that might alter the conclusion. Your goal is to follow the author's logic and separate facts from opinion
. Having done that, you usually will be able to identify conditions not stated in the argument that would have to be true for the conclusion to be valid. Ideally, isolating the conclusion from the premises should yield a couple of such assumptions. Consider the following argument:A recent study has shown that, all other characteristics being equal, bilingual persons memorize more quickly and retain information longer than those who speak only one language. Clearly, learning several languages can be used as a way to improve memory.
The premise here is that a person who speaks two languages has a better memory than those who speak only one. On this basis, the author concludes that learning several (more than two) languages can improve memory. You would accept this conclusion only if you, like the author, assumed that good memory is the result of learning two languages and not the cause, and that learning several languages has the same effect as learning only two does.
An answer choice that tends to deny these assumptions will cast doubt on the argument's conclusion. The correct answer choice will most likely introduce a new circumstance that makes the conclusion less likely to be valid. It is perfectly acceptable for Weaken answers to contain new information that was not included in the argument. The important thing is that this new piece of evidence should show that one or more of the author's key assumptions might not be true. Let's look at some possible Weaken answer choices for the above argument:Which of the following most seriously weakens the conclusion above?
A. None of the bilingual participants in the study possessed particularly good memory before starting to learn a second language.
B. A study of those knowing several languages has shown that their memories are no better than those of monolingual persons.
C. Monolingual speakers usually score better on tests of spatial reasoning.
D. Most of the study's participants who speak only one language have never tried to master another language.
E. Another study has revealed that the memory of those knowing several languages is only slightly better than that of bilingual persons.
In this case, Choice B casts the most serious doubt on the argument's conclusion because it attacks the second assumption, that if knowing two languages helps improve memory so does knowing more than two languages.
What answers to avoid
You can help yourself identify the correct answer choice if you eliminate the ones you know are wrong. In order to avoid these wrong choices, you should look for three things: (1) contradictions, (2) irrelevancies, and (3) strengtheners.
First, eliminate any choices that contradict the premises. GMAT expects you to act as if the premises are true, so a correct Weaken answer will usually leave the original facts of the argument untouched, though it may introduce new ones, showing how the conclusion might be false even if the premises are true.
Second, discard irrelevant choices. Many answer choices will address topics tangential to an argument without undermining the author's assumptions. Choice C above is a classic example of an irrelevancy: spatial reasoning has nothing to do with memory. Particularly in questions that ask you to explain why a plan might be unsuccessful, wrong options often contain general, irrelevant, criticism of the plan. What you need, however, is to figure out specifically why the author expects the plan to succeed and attack precisely that assumption.
Finally, answer choices may act in the wrong direction, having an effect opposite to what you want and strengthening the argument's conclusion. In the argument above, Choice A goes in the wrong direction. Such choices can be even more tempting than those containing irrelevant information, since they do seem to affect the conclusion. The way to avoid them is to keep in mind what kind of effect your choice must achieve.
When test-takers get Weaken questions wrong, it is usually because of failure to recognize them, addressing the wrong part of the argument, or not seeing the author's assumption. If you learn to recognize Weaken questions, analyze the arguments carefully, and figure out the assumptions that connect premises and conclusions, Weaken questions will not be an insurmountable challenge.http://gogmat.com/blog/17-gmat-study-guide/119-gmat-critical-reasoning-weaken-questions.html#.UnP8mXDryjg