Find the Correct Answer in Critical Reasoning on the GMAT

In critical reasoning, several factors can give away a potential incorrect answer choice. If the question is asking you to strengthen or weaken the author’s argument, the correct choice must always provide new information that either reinforces the author’s main point or calls into question its validity. However, certain answer choices give the illusion of talking about the subject without really saying anything conclusive about it (what one of my former professors colorfully called hand waving).

The answer choice must provide information that was previously unknown that would have an impact on the conclusion purported by the author. For example, if the author’s point is that cats obey their owners (yeah right!), then an answer choice that is true but has no relevance is that most cats’ breaths smell like cat food. This statement is undoubtedly correct, but doesn’t impact the conclusion (sorry Ralph Wiggum). Thus, for either strengthening or weakening, this choice fails the test.

Another type of incorrect answer choice is the statement that talks about the subject matter in a meaningless way. Keeping with the cat theme, if an answer choice indicates that “more people this year listed themselves as cat owners than did last year”. This answer is talking about the major points of the conclusion, but not in any meaningful way. This answer choice is basically just stating that there are new pussy cats (whoa whoa whoa), but doesn’t even begin to broach the subject of their obedience.

If we look at a representative GMAT example, let us identify (and eliminate) the answer choices that are irrelevant:

A year ago, Dietz Foods launched a yearlong advertising campaign for its canned tuna. Last year Dietz sold 12 million cans of tuna compared to the 10 million sold during the previous year, an increase directly attributable to new customers brought in by the campaign. Profits from the additional sales, however, were substantially less than the cost of the advertising campaign. Clearly, therefore, the campaign did nothing to further Dietz’s economic interests.

Which of the following, if true, most seriously weakens the argument?

(A) Sales of canned tuna account for a relatively small percentage of Dietz Foods’ profits.

(B) Most of the people who bought Dietz’s canned tuna for the first time as a result of the campaign were already loyal customers of other Dietz products.

(C) A less expensive advertising campaign would have brought in significantly fewer new customers for Dietz’s canned tuna than did the campaign Dietz Foods launched last year.

(D) Dietz made money on sales of canned tuna last year.

(E) In each of the past five years, there was a steep, industry-wide decline in sales of canned tuna.

Looking through the answer choices, some already seem very hard to defend. Let us nonetheless proceed in order. Answer choice A says that canned tuna didn’t make much profit (shocking, I know). However this doesn’t change the fact that the company spent a lot on canned tuna advertising and didn’t get the return it wanted from the campaign. Answer choice A doesn’t seem to weaken the argument, and in fact it reinforces the idea that the whole idea was bad for business.

Answer choice B kind of conflictingly says that the first-time buyers of tuna already purchased other Dietz products. This is possible, in the sense that they bought lots of Dietz products but did not realize that the company also made canned tuna. In that sense, the company enlarged its target market, but what percentage of the 12 million cans sold was bought by first time buyers? 5%? 50%? 1%? This answer doesn’t shed any light on the percentage of first time buyers, and thus doesn’t give us enough information to weaken the argument.

Answer choice C is a perfect example of hand waving. A cheaper campaign would have brought in less new customers. This sounds like a tempting answer choice, but again the issue of quantifiable numbers would help tremendously. If the campaign cost 90% less but brought in 50% less customers, would it have been a success? Or if the alternative had cost 50% less but brought in 90% fewer customers? Both situations are possible from the statement, but they have different outcomes. Answer choice C can be true without weakening the conclusion in any way, so it cannot be the correct choice, although many people are tempted by this answer.

Answer choice D is tantamount to “my cats’ breath smells like cat food”. This statement is undoubtedly true, but it does nothing to refute the author’s conclusion.

By process of elimination, answer choice E must be the correct answer. This choice also makes sense, because it confirms that the industry as a whole is decreasing in sales. This means that the uptick in tuna sales for Dietz is not a case of an industry-wide increase. As the old adage says “A rising tide raises all ships”. If the industry were booming, then the increase in sales could just be a side-effect of being in the tuna business. Since the tuna business is going belly up (see what I did there?), the increase in sales must be a direct result of the marketing campaign, and not just a case of good fortune.

When looking over the answer choices in a weaken question, don’t be swayed by tempting answer choices that don’t provide any new information. Particularly if asked to weaken an argument, the goal is to find plausible alternatives to the author’s stated conclusion, not choices that seem right. Your goal is to find the answer choice that actually weakens the question, and to be on the lookout for answer choices that seem fishy.

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Ron Awad is a GMAT instructor for Veritas Prep based in Montreal, bringing you weekly advice for success on your exam.  After graduating from McGill and receiving his MBA from Concordia, Ron started teaching GMAT prep and his Veritas Prep students have given him rave reviews ever since.