Although GMAT Critical Reasoning questions come in several different varieties, the most common are by far and away those involving an unstated assumption upon which the correct answer depends. These questions usually take one of the following formats: “Which of the following would (strengthen/weaken) the argument?” and “The argument above assumes which of the following?” All GMAT critical reason arguments can be broken into three distinct parts: the evidence, the assumption, and the conclusion. Taken together, we can say that EVIDENCE +
Understanding how the evidence provided in the argument leads the reader toward the conclusion without necessarily guaranteeing the validity of the conclusion is how you begin the critical process of identifying unstated assumptions. The evidence is employed in order to make the conclusion sound likely or legitimate, but is invariably insufficient. The ways in which the evidence doesn’t make a complete case for the conclusion all point toward the assumptions without which the argument would fall apart. Consider the following argument:
AllMedia is a company that owns bookstores nationwide. In 2008 the city of Los Angeles had 60% the number of bookstores it had ten years earlier in 1998, and its residents were three times more likely to order a book from an on-line distributor than they were to purchase it at a brick-and-mortar bookstore. Advisors on the company’s board cited these statistics in their proposal that the company should redirect funds to its other interests, since bookstores are clearly on the decline.
Which of the following most weakens the advisors’ argument?
After you’ve analyzed the argument and identified the conclusion (the last sentence above) and the evidence (everything else), you might glance at the answer choices. Now, typically the answer choices will include a couple statements that could actually weaken the argument, as well as a couple statements that have little or no bearing on the argument. The answer choices which have little or no bearing on the argument will often propose adjustments to the evidence given in the question stem or introduce new evidence. (An example for this question might be something like, “In 2008 there were 18 bookstores as then unbuilt but in the works.”) These answer choices can be eliminated quickly, since the correct answer to a “weaken” question will never deal with evidence, but rather assumptions.
In order to most effectively predict which statement most weakens the argument, you must first predict what assumptions the argument makes. Every argument invariably makes numerous assumptions, of which only a few will be most pivotal in the argument’s structure. You can test the strength of an assumption by denying it and examining the impact of that denial on the coherence of the argument as a whole. For example, the argument above assumes that people in and around Los Angeles would not patronize a new or improved AllMedia bookstore. If, in fact, residents are not frequenting bookstore simply because the existing bookstores are out of date or inaccessible, then one could argue that channeling funds to a new bookstore venture might be a good investment and that bookstores aren’t necessarily on the decline. While the correct answer might be more oblique in its presentation and will not present an explanation of its logic, it’s a simple task for you to determine the best choice using the tips laid out above.