Flaw Questions

Learning Objectives

In this section, you will learn how to: 

• Identify Flaw questions by the question stem
• Predict the manner in which an argument is flawed by identifying conclusion, evidence, and assumptions
• Apply the Kaplan Method for Critical Reasoning to Flaw questions

Flaw questions are similar to Weaken questions, but instead of asking you for some new fact that, if true, would make the argument questionable, Flaw questions ask what’s already wrong with the argument. So your prediction should focus on reasoning errors the author makes.

The good news is that the GMAT uses a handful of common flaws over and over. Here are the two general categories of errors in reasoning:

1. Unsupportable shifts between the concepts in the evidence and conclusion
2. Overlooked alternatives

And here are some common patterns that show up:

• Confusing correlation and causation
• Confusing percent and actual value
• Inappropriate analogies (comparing things that aren’t comparable)
• Inappropriate conflation/distinction of terms
  

All of these flaws and any others you find in GMAT Critical Reasoning questions center on the author’s assumption, so you should handle them similarly to how you’ve handled all the other argument-based questions so far: by identifying the conclusion, evidence, and assumption. 

Sample Stems

Here are some example question stems that indicate a Flaw question:

• Which of the following is a flaw in the reasoning above?
• The argument above is vulnerable to which of the following criticisms?

Applying the Kaplan Method: Flaw Questions

Now let’s use the Kaplan Method for Critical Reasoning to solve a Flaw question:

1. The public service advertising campaign promoting the use of helmets has improved bicycle safety dramatically. Over the past 12 months, the number of serious bicycling injuries has been reduced by nearly 70 percent. Unfortunately, helmet usage has not reduced the number of all types of bike injuries. While serious head trauma has decreased by nearly 85 percent, broken bones now represent 20 percent of all reported bicycling injuries. This is a significant increase from last year’s 14 percent.

   The reasoning in the argument is flawed because the argument does which of the following?

   1. It fails to include information about any types of bicycle injuries other than head trauma and broken bones.
   2. It implies that the same conclusion can result from two different sets of causes.
   3. It fails to take into account any possible increase in the number of people riding bicycles over the past 12 months.
   4. It presumes that an increase in the percentage of injuries involving broken bones precludes a decrease in the actual number of such injuries.
   5. It ignores the fact that a 70 percent overall decrease in injuries would not allow for an 85 percent decrease in one specific type of injury.

Step 1: Identify the Question Type

The question stem alerts you to the idea that this argument is flawed, so Flaw is definitely the question type here.

Step 2: Untangle the Stimulus

The author concludes that the number of broken-bone bicycle injuries has gone up from last year to this year. The evidence for this is that broken bones made up 20 percent of this year’s total bicycle-related injuries but were only 14 percent of last year’s total.

Step 3: Predict the Answer

As soon as you see both percentages and numbers mentioned in the stimulus for a Flaw question, beware. In the Quantitative section, you will learn, if you have not already, that you must be careful when working with percentages. Twenty percent is guaranteed to equal a higher number than 14 percent only if those percentages are of the same total. And since the total number of injuries is much lower this year than last year, 20 percent of a much lower total could actually equal a lower number than 14 percent of last year’s higher total.

If you’re having trouble seeing this, you can use the Quant strategy of Picking Numbers. Suppose there were 100 bicycle injuries last year. That means that 14 percent, or 14 total, of those injuries involved broken bones. You know that this year, injuries have been reduced by 70 percent. In this example, that means there were a total of 30 bicycle injuries this year. Twenty percent of the new, lower total is 6 broken-bone injuries, a significantly lower number than last year’s 14. The flaw here is the author’s assumption that an increase in percentage cannot be consistent with a decrease in actual number.

Step 4: Evaluate the Choices

Only (D) accurately captures the logical flaw in this argument—confusing percent and actual value. (D) is the correct answer. 

The fact that the author mentions only two types of injuries, as (A) says, is not a flaw in the argument, which concerns only whether or not the number of broken bones has been reduced. Other types of injuries are irrelevant. Since two sets of causes aren’t discussed, you can rule out (B). Causation does figure in many GMAT flaws, but not this one. (C) might seem tempting, since it does relate to the “percentage versus actual number” issue, but if the total number of bicyclists increased over the past year, the reduction in the number of total injuries would actually be greater. And since a 70 percent overall decrease in injuries could, in fact, allow for an 85 percent decrease in one specific type of injury, (E) can be ruled out as well.

Takeaways: Flaw Questions

• Flaw questions ask you to describe how the author’s reasoning has gone awry. Identifying the author’s assumption will reveal the flawed thinking.
• Some classic flaws include mistaking correlation for causation and confusing actual value with percent.
• On Flaw questions, determine the conclusion, evidence, and central assumption(s). Then predict an answer describing the reasoning error in the author’s assumption.

Practice Set: Flaw Questions

10. Our legislature is considering passing legislation to ban skateboarding on city streets, citing safety concerns. However, a review of public health records reveals that the legislature’s concern is misplaced. Each year, many more people are injured while jogging than are injured while skateboarding. So in fact, skateboarding is safer than jogging.
    Which of the following indicates a flaw in the reasoning above?
    1. It fails to distinguish professional skateboarders who attempt very dangerous maneuvers from amateurs who are comparatively cautious.
    2. It assumes without warrant that no one who skateboards also jogs.
    3. It fails to consider the number of people who skateboard as compared with the number of people who jog.
    4. It ignores the possibility that other activities cause even more injuries than either skateboarding or jogging.
    5. It fails to address the issue and instead attacks the character of the legislature.
11. Solo concert pianists, by convention, are not permitted to use musical scores during their performances. However, most members of chamber groups and orchestras are permitted to use sheet music during performances and perform well as a result. Therefore, all solo concert pianists should also be allowed to consult their musical scores during performances. 
    The argument is most vulnerable to criticism on which of these grounds?
    1. It overlooks the possibility that some solo concert pianists prefer performing without consulting musical scores.
    2. It takes for granted that members of a chamber group or orchestra are less skilled than solo musicians and thus have more need for musical scores. 
    3. It overlooks the possibility that some solo concert pianists have broken with tradition and used musical scores during their performances.
    4. It takes for granted that a solo concert pianist would use a musical score in the same way as does a member of a chamber group or orchestra.
    5. It overlooks the possibility that performing in an orchestra is difficult despite the ability to use a musical score during the performance.