The key to weakening an GMAT argument is to attack the conclusion. But, keep in mind that to attack is not the same as to destroy. Although an answer that destroys the conclusion would be correct, this rarely occurs because of the minimal space allotted to answer choices. Instead, you are more likely to encounter an answer that hurts the argument but does not ultimately destroy the author’s position. When evaluating an answer, ask yourself, “Would this answer choice make the author reconsider his or her position or force the author to respond?” If so, you have the correct answer.
Because arguments are made up of premises and conclusions, you can safely assume that these are the parts you must attack in order to weaken an argument. Let us discuss each part, and the likelihood that each would be attacked by an answer choice.
1. The Premises
One of the classic ways to attack an argument is to attack the premises on which the conclusion rests. Regrettably, this form of attack is rarely used on the GMAT because when a premise is attacked, the answer choice is easy to spot. Literally, the answer will contradict one of the premises, and most students are capable of reading an argument and then identifying an answer that simply negates a premise.
In practice, almost all correct GMAT Weaken question answers leave the premises untouched.
2. The Conclusion
The conclusion is the part of the argument that is most likely to be attacked, but the correct answer choice will not simply contradict the conclusion. Instead, the correct answer will undermine the conclusion by showing that the conclusion fails to account for some element or possibility. In this sense, the correct answer often shows that the conclusion does not necessarily follow from the premises even if the premises are true. Consider the following example:
All my neighbors own blue cars. Therefore I own a blue car.
Even though the statement that the neighbors have blue cars is entirely reasonable, the weakness in the argument is that this fact has no impact on the color of the car I own. In this overly simplified problem, the correct weakening answer would be something along the lines of, “The cars of one’s neighbors have no determinative effect on the car any individual owns.” Would that conclusively disprove that I own a blue car? No. Does it show that perhaps I do not own a blue car? Yes. Does it disprove that my neighbors own blue cars? No.
Answers that weaken the argument’s conclusion will attack assumptions made by the author. In the example above, the author assumes that the neighbors’ ownership of blue cars has an impact on the color of the car that he owns. If this assumption were shown to be questionable, the argument would be undermined.
The stimuli for weaken questions contain errors of assumption. This makes sense, because the easiest argument to weaken is one that already has a flaw. Typically, the author will fail to consider other possibilities or leave out a key piece of information. In this sense the author assumes that these elements do not exist when he or she makes the conclusion, and if you see a gap or hole in the argument immediately consider that the correct answer might attack this hole.
As you consider possible answers, always look for the one that attacks the way the author arrived at the conclusion. Do not worry about the premises and instead focus on the effect the answer has on the conclusion.
So, we know that we must first focus on the conclusion and how the author arrived at the conclusion. The second key to weakening arguments is to personalize the argument. Most students perform considerably better when they see the argument from their perspective as opposed to trying to understand the issues abstractly. When analyzing the author’s argument, imagine how you would respond if you were talking directly to the author. Would you use answer choice (A) or would you prefer answer choice (B)? Students who personalize the argument often properly dismiss answer choices that they would have otherwise wasted time considering.