Solving “Weaken” Questions

Here are some ways that the question might ask you to weaken the argument’s main conclusion:

• Which one of the following, if true, most seriously weakens the argument?
• Which one of the following, if true, most seriously undermines the government’s claims?
• Which one of the following, if true, most seriously calls into question the conclusion above?

Make a Strong Prediction

Arguments are either valid or invalid. Therefore, if you’re being asked to weaken an argument, it must be flawed in at least one way. Ideally, you’ve already pinpointed a flaw by actively engaging with the passage right off the bat. If not, here’s how to spot a flaw:

1. Identify the main conclusion and restate it in plain terms. Learn more about identifying conclusions here and here. 
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2. Identify the premises. Distinguish these from any concessions, background information, or opposing viewpoints that might be part of the passage.
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3. Understand why the premises don’t prove the main conclusion. Since the argument is flawed, you already know that by definition the premises do not prove the conclusion. Why not? 

Imagine that the opposing counsel is making this argument and it’s your job to disprove it. Even if you don’t predict the correct answer word for word, identifying flaws will give you a head start on finding the argument’s most glaring weak points. 

What to Look For

The answer choices will give you new evidence. The correct answer will make you doubt the conclusion without directly contradicting the evidence stated in the passage.

Consider this argument:

Partner John will be a good fit at our firm because he has worked at two other prestigious law firms.

The correct answer might say something like:

(B) John only worked at each firm for two weeks.

This new evidence doesn’t contradict the premises—he still worked at two prestigious law firms—but it does cast doubt on the conclusion that he would be a good fit by raising a potential problem. What if his experience at those firms isn’t as significant as the argument implies? 

Don’t skip an answer just because it doesn’t address the points raised in the original argument. Here’s another potentially correct answer:

(C) John recently broke up with Sally, our firm’s managing partner.

This new evidence has nothing to do with the original premises, nor does it contradict them, but it does give us a new reason to doubt whether he would be a good fit at the firm. 

Top Tips

As you read the choices, ask yourself: Does this answer choice hurt the main conclusion more than the other four? Here’s how:

1. Assume that all five answers are true. 
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2. If you’re debating between two answers that both hurt the conclusion, pick the one that hurts more. Once you’re satisfied that the content of an answer is relevant to the argument, then turn your focus to word strength. The correct answer often (but not always) uses strong wording such as all or most rather than some or many.
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3. If the question uses the word “EXCEPT,” the correct answer will either strengthen the conclusion or do nothing. In this case, cross out answers that weaken the conclusion at all.