GMAT Critical Reasoning: The Denial Test
July 7, 2012
In your GMAT preparation you have probably learned to tackle critical reasoning assumption questions by identifying the conclusion of the argument, followed by the evidence and then looking for the missing link between these, which will be the central assumption. However, you have also probably encountered GMAT problems in which you either cannot figure out what the assumption is before you go to the answer choices or the assumption you found is not listed as an option. When this happens you want to be ready with a backup strategy.
The standard backup strategy for assumption questions – and do keep in mind this should not be used as a primary strategy, since it is more time consuming than the usual approach – is the denial test.
The denial test is based on the idea that the assumption is something that must be true in order to link the evidence to the conclusion. Another way to think about this is that if the assumption were not true, the evidence would no longer lead to the conclusion; that is, the argument would fall apart.
Therefore, as long as you have identified both the conclusion and evidence you can apply the denial test by negating each answer choice. Once you negate the option, see if the argument can still be true, even though the answer choice is false. If the argument cannot be true once the choice has been negated, you have found your assumption
For example, in the argument “poisons are harmful, therefore chemical X is harmful,” the conclusion is “chemical X is harmful” and the evidence is “poisons are harmful.” If an answer choice for the assumption said “chemical X is a poison,” we would negate this by making it “chemical X is not a poison.” If we know that chemical X is not a poison, then knowing that poisons are harmful tells us nothing about chemical X and the argument falls apart. Thus, we have found our assumption.
By using this strategy on GMAT test day when you get stuck on an assumption question you will be able to find the right answer without either guessing or using a method that is not working for you on that problem. Give it a try on the question below.
Politician: It is important for members of the State Assembly to remember that Governor Norman’s proposed new state thruway was part of her platform during her landslide re – election campaign last year. This means that if the thruway plan is defeated, its opponents will have much to answer for in next November’s State Assembly elections.
The politician’s argument relies upon which of the following assumptions?
|o||A.||Many of those who voted for Governor Norman oppose the thruway proposal.|
|o||B.||The thruway proposal is likely to be defeated by the State Assembly.|
|o||C.||Many of those who voted for Governor Norman supported the thruway proposal.|
|o||D.||Everyone who voted for Governor Norman last year will vote in the State Assembly elections.|
|o||E.||Those members of the State Assembly who oppose the thruway proposal do not have valid reasons for opposing it.|
The question stem asks us to identify an assumption. Read the stimulus and find the evidence and conclusion. How do they differ? The assumption holds the evidence and conclusion together despite their apparent differences.
When the Governor won by a landslide, her platform included a thruway proposal. Based on this evidence, the politician concludes that if the thruway plan is shot down in the State Assembly, those responsible for its defeat will be in big trouble come election time.
The author assumes that the Governor won because her platform included a thruway proposal. But for all we know, the Governor may have won despite, not because of, the proposal. If the November threat to thruway opponents is real, it must be true that many of those who contributed to the landslide also support the project.
Choice (C) is a perfect replica of the paraphrase above. If, in fact, many who voted for Norman support the thruway, then the politician’s conclusion is surely reasonable — opponents of the thruway may be in hot water with the voters, at least over this issue.
Choice (A) is the exact denial of correct Choice (C). The fact that many of Norman’s supporters oppose the thruway would substantially weaken the politician’s argument.
Choice (B) goes beyond the scope of the argument by assessing the thruway proposal’s chances. The argument is based on the hypothetical “If it is defeated . . .” So even if it is not likely to be defeated, the threat may still be real should the defeat actually occur. The word if ensures that the chance of defeat plays no role in the validity of the argument.
Choice (D) is also not necessary to the argument. Even if not everyone who voted for the Governor last year votes in the State Assembly elections, enough of them may vote to cause trouble for thruway opponents — if those voters support the project.
Choice (E) is irrelevant to the argument. No matter what reasons the members of the State Assembly have for opposing the thruway, the Governor’s voters may not forgive them for a thruway defeat. Nothing regarding the validity of the opposition is required here.
The answer is C