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Let’s review the two roles played by assumptions:

Supporter Assumption: These assumptions link together new or rogue elements in the stimulus or fill logical gaps in the argument.

Defender Assumption: These assumptions contain statements that eliminate ideas or assertions that would undermine the conclusion. In this sense, they “defend” the argument by showing that a possible source of attack has been eliminated.

Three Quirks of Assumption Question Answer Choices

Over the years, certain recurring traits have appeared in Assumption answer choices. Recognizing these quirks may help you eliminate wrong answers or more quickly identify the
correct answer at crunch time.

1. Watch for answers starting with the phrase “at least one” or “at least some.”

For some reason, when an Assumption answer choice starts with either of the above constructions the chances are unusually high that the answer will be correct. However, if you spot an answer with that construction, do not simply assume the answer is correct; instead, use the proper negation (“None”) and check the answer with the Assumption Negation Technique.

2. Avoid answers that claim an idea was the most important consideration for the author.

These answers typically use constructions such as “the primary purpose,” “the top priority,” or “the main factor.” In every Assumption question these answers have been wrong. And, unless, the author specifically discusses the prioritization of ideas in the stimulus, these answers will continue to be wrong because an author can always claim that the idea under discussion was very important but not necessarily the most important idea.

3. Watch for the use of “not” or negatives in assumption answer choices.

Because most students are conditioned to think of assumptions as positive connecting elements, the appearance of a negative in an Assumption answer choice often causes the answer to be classified a Loser. Do not rule out a negative answer choice just because you are used to seeing assumptions as a positive part of the argument. As we have seen with Defender answer choices, one role an assumption can play is to eliminate ideas that could attack the argument. To do so, Defender answer choices frequently contain negative terms such as “no,” “not,” and “never.” One benefit of this negative language is that Defender answer choices can usually be negated quite easily.

Assumptions and Causality

“When a GMAT speaker concludes that one occurrence caused another, that speaker also assumes that the stated cause is the only possible cause of the effect and that the stated cause will always produce the effect.”

Thus, because the author always assumes that the stated cause is the only cause, Assumption answer choices tend to work exactly like Strengthen answer choices in arguments with causal reasoning. The correct answer to an Assumption question will normally fit one of the following categories:

A. Eliminates an alternate cause for the stated effect

Because the author believes there is only one cause (the stated cause in the argument), the author assumes no other cause exists.

B. Shows that when the cause occurs, the effect occurs

Because the author believes that the cause always produces the effect, assumption answers will affirm this relationship.

C. Shows that when the cause does not occur, the effect does not occur

Using the reasoning in the previous point, the author will always assume that when the cause does not occur, the effect will not occur.

D. Eliminates the possibility that the stated relationship is reversed

Because the author believes that the cause-and-effect relationship is correctly stated, the author assumes that the relationship cannot be backwards (the claimed effect is actually the cause of the claimed cause).

E. Shows that the data used to make the causal statement are accurate, or eliminates possible problems with the data

If the data used to make a causal statement are in error, then the validity of the causal claim is in question. The author assumes that this cannot be the case and that the data are accurate.