Critical Reasoning
Critical Reasoning Stimuli
Some stimuli contain only facts. But most stimuli contain an argument, in which the author advocates for a particular position based on the facts presented. In these cases, it's important to identify the argument’s primary conclusion. A conclusion can appear anywhere within a stimulus, and may be associated with a keyword such as therefore, thus, hence, demonstrates that, as a result, and conclude. Sometimes the conclusion is a cause-and-effect relationship. Also identify reasons upon which the conclusion is based. These reasons (called premises) may be associated with a keyword such as because, since, assuming, due to, and given that. Finally, arguments typically contain one or more assumptions, unstated facts upon which the conclusion depends.
GMAT Critical Reasoning Question Types
When reading the question stem, identify what the question is asking you to do. According to the GMAT Genius classification system, there are six primary and three applied question types. Each CR question type has certain techniques that can help you choose the correct answer.
- Weaken – point out a flaw in the argument or make the conclusion less likely to be true.
- Strengthen – improve the argument or make the conclusion more likely to be true.
- Assumption – identify an assumption that is absolutely essential for the conclusion to be true.
- Reasoning – either describe the flawed reasoning used within an argument or describe the argument's structure.
- Conclusion – draw a conclusion or inference from the facts in the stimulus, or identify what must be true.
- Explain – reconcile two seemingly contradictory facts that appear in the stimulus.
- Evaluate – find information that would help you assess the argument's validity.
- Boldface – describe the role played by two boldfaced portions of the stimulus.
- Complete the Passage – identify what that would logically complete the ending of the stimulus.
How to Approach GMAT Critical Reasoning
Some companies recommend that you read the question before reading the stimulus. We strongly disagree. There are two disadvantages to reading the question initially. First, you then tend to look for a certain answer while reading the stimulus and may overlook important subtleties. Second, you will often have to read the question a second time, either because you forgot what the question was asking or you didn’t have the context of the stimulus to fully interpret the question. As a result, you waste valuable time.
Instead, critically read and evaluate the stimulus before worrying about the question. After doing so, you can often identify (or at least narrow down) the correct answer without referring back to the stimulus. The best LSAT preparation companies recommend reading the stimulus initially for this reason. That said, identify which approach works best for you. Try 10 CR questions at one go, reading the stimulus first on five questions and then reading the question first on the next five. In our experience, most students recognize, in doing so, that they prefer reading the stimulus first.
After carefully reading the stimulus and question stem, consider the five answer choices. Some companies recommend "pre-thinking" the correct answer first. Pre-thinking is a terrible approach in our opinion. Although this may work on easy-difficulty questions, it rarely works on hard-difficulty questions, which don't list an obvious answer among the answer choices. Furthermore, why waste valuable time anticipating what may be the correct answer instead of just reading the answers presented.
Process of elimination is important when reviewing the answers. Take a first quick pass through all five answers to familiarize yourself with the options and to eliminate answers that are definitely wrong. Do not spend much time evaluating answers in the first pass, because you may identify a subsequent answer as the clear correct choice. Only after the first pass, take a second pass at the worthwhile answers, referring back to the stimulus as necessary to choose the correct answer.
Sample GMAT Critical Reasoning Problem
Let’s try a sample problem. Attempt the problem on your own before viewing the answer and explanation.
There are far fewer kidney donors available than there are people who need kidneys. In the U.S. alone, 95,000 people currently wait on the official kidney transplant list. But two years ago, the last year for which data is available, just 16,500 people received a kidney transplant.
Which of the following statements, if true, most strengthens the author’s claim that there are far fewer kidney donors available than there are people who need kidneys?
| (A) | The number of people on the official kidney transplant list has increased dramatically over the past two years. |
| (B) | The number of kidney transplants in the current year is greater than the number of kidney transplants in any preceding year. |
| (C) | People on the official kidney transplant list generally are valued members of society. |
| (D) | People who need kidneys often go through a long process of medical testing and evaluation by doctors. |
| (E) | The number of kidney transplants in a year is approximately equal to the number of available kidney donors in that period. |
Explanation to Problem
Answer: E
The first sentence of the stimulus is the conclusion: there are far fewer kidney donors available than there are people who need kidneys. This is a classic supply-demand imbalance issue. The supply (available kidney donors) cannot meet the demand (number of people on the kidney transplant list). Although we know this to be true in the real world, we must consider whether the author offers an airtight argument.
As premises, the author offers two pieces of data. First, there are currently 95,000 people on the official kidney transplant list. Second, two years ago, there were only 16,500 kidney transplants. Unfortunately, the premises do not offer definite proof of a supply-demand imbalance. Two problems stand out:
The years are different. We do not know how many people were on the official kidney transplant list two years ago, nor do we know how many kidney transplants currently occur. Perhaps only 16,500 people were on the official transplant list two years ago and perhaps 95,000 kidney transplants will take place in the current year. If so, there really is no supply-demand imbalance.
We are told the number of kidney transplants that occurred two years ago, but we do not know how many kidney donors were available. The author is assuming that the number of kidney transplants is a good proxy for the number of available donors, but this doesn’t necessarily have to be the case. Perhaps the number of available donors was equal to the number of people on the transplant list, but far fewer transplants occurred for some other reason, such as bureaucratic snafus.
This is a Strengthen question, as indicated by the words “most strengthens” in the question. For these questions, incorrect answers will either be irrelevant or actually weaken the argument (the opposite of our objective). Our correct answer will most likely focus on fixing one of the flaws that we listed above.
Answer Choices
| (A) | This answer relates to the first flaw that we identified in the argument, but actually weakens the argument. By stating that the number of people on the official transplant list has increased dramatically, we can infer that significantly fewer people were on the list two years ago. So perhaps there was not a big difference between the number of people on the list two years ago and the number of transplants that occurred two years ago. |
| (B) | As with answer A, this also relates to the first flaw and weakens. By stating that the number of transplants in the current year is greater than preceding years, it indicates that the current year transplants is closer to 95,000 than we were previously led to believe. Although this answer does not say how much bigger the current year number is, we do know that it is bigger than 16,500. So it definitely does not strengthen the argument. |
| (C) | This answer is irrelevant. By stating that those on the transplant list are valued members of society, it indicates that the supposed supply-demand imbalance is a big concern. After all, if the transplant list consisted only of violent criminals, we may not be as concerned about the supply-demand imbalance. But regardless of who is on the list, this answer does not have relevance as to whether a supply-demand imbalance exists. |
| (D) | This answer is also irrelevant. By stating that those on the transplant list undergo extensive testing and evaluation, it indicates that those on the list truly need a kidney. They are not placed on the list frivolously. But as with answer C, this does not have relevance as to whether a supply-demand imbalance exists. |
| (E) | This is our correct answer, because it fixes the second flaw that we identified in the argument. By stating that the number of kidney transplants in a year equals the number of donors, we can now say that 16,500 donors were available two years ago. We were thus incorrect in our speculation that perhaps we had far more donors available, but few transplants due to another reason such as bureaucratic snafus. By removing some doubt, we have strengthened the argument. Our correct answer does not have to fix every flaw in the argument; it just has to improve the argument in some way. |
