GMAT : Analysis of An Argument

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An Argument

17. The following appeared in an article in a consumer-products magazine.

Two of today's best-selling brands of full-strength prescription medication for the relief of excess stomach acid, Acid-Ease and Peptiaid are now available in milder non-prescription forms. Doctors have written 76 million more prescriptions for full-strength Acid-Ease than for full-strength Peptiaid. So people who need an effective but milder non-prescription medication for the relief of excess stomach acid should choose Acid-Ease.


Discuss how well reasoned you find this argument. In your discussion be sure to analyze the line of reasoning and the use of evidence in the argument. For example, you may need to consider what questionable assumptions underline the thinking and what alternative explanations or counterexamples might weaken the conclusion. You can also discuss what sort of evidence would strengthen or refute the argument, what changes in the argument would make it more logically sound and what, if anything, would help you better evaluate in conclusion.


This ad recommends non-prescription Acid-Ease over non-prescription Peptic aid for relief of excess stomach acid. The only reason offered is that doctors have written 76 million more prescriptions for the full-strength prescription form of Acid- Ease than for full-strength Peptiaid.

While this reason is relevant and provides some grounds for preferring Acid-Ease over Peptiaid, it is insufficient as it stands because it depends on three unwarranted assumptions.

The first assumption is that the prescription form of Acid-Ease is more popular among doctors. But this might not be the case, even though doctors have written 76 million more prescriptions for Acid-Ease. Acid-Ease may have been available for several more years than Peptiaid. And in the years when both products were available Peptiaid might have actually been prescribed more often than Acid-Ease.

The second assumption is that doctors prefer the prescription form of Acid-Ease for the reason that it is in fact more effective at relieving excess stomach acid. However, doctors may have preferred Acid-Ease for reasons other than its effectiveness. Perhaps Acid-Ease is produced by a larger, more familiar drug company or by one that distributes more free samples. For that matter, the medical community may have simply been mistaken in thinking that Acid-Ease is more effective. In short, the number of prescriptions by itself is not conclusive as to whether one product is actually better than another.

The third assumption is that the milder non-prescription forms of Acid-Ease and Peptiaid will be analogous to the full-strength prescription forms of each. But this might not be the case. Suppose for the moment that the greater effectiveness of prescription Acid-Ease has been established. Even so, the non-prescription form might not measure up to non-prescription Peptiaid. This fact must be established independently.

In conclusion, this ad does not provide enough support for its recommending non-prescription Acid-Ease over non-prescription Peptiaid.

To strengthen its argument, the promoter of Acid-Ease will have to show that

(1) The comparison between the numbers of prescriptions is based on the same time period.

(2) Its effectiveness is the main reason more doctors have prescribed it.

(3) The comparative effectiveness of the two non-prescription forms is analogous to that of the prescription forms.

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