Critical Reasoning
Verbal
14 min readYou’re taking the GMAT to go to business school, not to get a PhD in philosophy, so you’re probably wondering why you need to be tested in logic and critical reasoning. Don’t worry — answering the critical reasoning questions on the GMAT doesn’t require any knowledge of formal logic. You won’t be constructing syllogisms or using fancy Latin words, like ad hominem, for logical fallacies. The GMAT verbal section contains questions that test you on informal logic, which is a lot like the kind of reasoning you use to decide between a chocolate frosted doughnut and a bran muffin when the office pastry cart passes by. We fill you in on this logic (for the GMAT, not the pastry cart) in this chapter. The people who run the admissions offices at business schools want to make sure their future students can think through situations clearly and carefully. That’s where the critical reasoning questions come in.
About half of the 23 questions in the GMAT verbal section are critical reasoning questions. This question type tests your ability to analyze an argument. The good news is that you analyze arguments all the time, even though you may not know you’re doing so. When you see a commercial advertising a new product that claims it’ll make your life better, you probably question that claim. If a weight-loss drug helped someone lose 50 pounds, you ask, “Is that a typical result?” If four out of five dentists recommend a chewing gum, you say, “Did they ask only five dentists?” When a mutual fund boasts of its performance, you ask, “Is that better than the market average?” You’ll use this same kind of thinking to ace the critical reasoning questions on the GMAT.
Critical reasoning questions consist of an argument, a question, and five answer choices, of which only one is correct. You’ll encounter short passages from a variety of sources, such as speeches, advertisements, newspapers, and scholarly articles. You may see an argument like this: “The local sales tax must be raised to fund city services. Admittedly, this increased sales tax will impose a greater hardship on the poorest citizens. But if the sales tax is not increased, all city services for the poor will have to be cut.” The paragraph reflects the type of arguments you encounter in the news every day.
Each critical reasoning question has essentially the same structure. The question usually begins with a two- to five-sentence paragraph that contains the argument. The question contains all the information you need to answer the question. Don’t rely on any outside information! Even if you happen to be an expert in the area a question covers, don’t rely on your expertise to answer the question.
The short argument paragraph is followed by a question. The questions usually fall conveniently into one of a few types. The question may ask that you weaken or strengthen an argument, draw a conclusion, analyze the structure of an argument, or identify an unstated assumption the author makes. We examine each of these question types in the section, “Getting from Point A to Point B: Types of reasoning,” later in this chapter.
Each question has five possible answer choices, which are often long, sometimes even longer than the argument or question. For this reason, you’ll spend most of your time for each question examining the answer choices.
As with most GMAT questions, you can quickly eliminate one or two of the answers that are obviously wrong. The remaining answers will be more difficult to eliminate, so spend your time analyzing these better answer choices.
To break down a critical reasoning question, follow these three steps:
The best way to tackle a critical reasoning question is to read the question first to determine its type. The later section, “Thinking Inside the Box: Question Types,” shows you how to distinguish critical reasoning question types. When you first read the question, don’t read all the answer choices; doing so takes way too much time and clutters your thinking. You need to concentrate on only the information you need to find to answer the question.
After you figure out what kind of question you’re dealing with, you can read the paragraph very carefully. Be sure to locate the conclusion of the argument. The conclusion may come at the beginning, middle, or end of the paragraph. When you’ve identified the conclusion, you can better understand the rest of the paragraph. As you read the paragraph, look for inconsistencies or gaps in the argument that may help you answer the question. Isolating the argument’s premises, assumptions, and conclusion helps you determine the method of reasoning.
The argument paragraph usually isn’t too complicated, and therefore you may be tempted to read it too quickly. Force yourself to read slowly and carefully so you don’t skim over the word or words that provide the keys to the argument. If you read thoroughly enough, you’ll be able to eliminate some — or even most — of the answer choices. When you’re down to two possible answers, you can then easily refer back to the text to make sure you choose the correct answer.
You can score well on the GMAT critical reasoning questions without knowing the elements of informal logic, but if you understand a few terms and concepts, you can score even higher. You really just need to know the two basic components of a logical argument and a few methods of coming up with a conclusion, which we outline in the following sections.
A logical argument consists of premises and a conclusion, and when you’re analyzing arguments, identifying what parts are premises and what makes up the conclusion can help. The premises give the supporting evidence that you can draw a conclusion from. You can usually find the conclusion in the argument because it’s the statement that you can preface with therefore. The conclusion is often but not always the last sentence of the argument. For example, take a look at this simple argument:
All runners are fast. John is a runner. Therefore, John is fast.
The premises in the argument are “All runners are fast” and “John is a runner.” They provide the supporting evidence for the conclusion that John is fast, which is the sentence that begins with therefore. Not all conclusions in the GMAT critical reasoning arguments will begin with therefore or other words like it (such as thus and so), but you can try adding therefore to any statement you believe is the conclusion to see whether the argument makes sense. We give you plenty of sample arguments in this chapter so you can use them to practice identifying premises and conclusions.
Each logical argument has premises and a conclusion, but not every argument comes to a conclusion in the same way. For the purposes of the GMAT, you should be familiar with two basic types of logical reasoning: deductive and inductive (which we explain further in the next sections). You use both types of reasoning all the time, but now you can apply definitions to your logical genius.
In deductive reasoning, you come up with a specific conclusion from more general premises. The great thing about deductive reasoning is that if the premises are true, the conclusion must be true! The following is an example of a deductive reasoning argument:
All horses have hooves. (General premise)
Bella is a horse. (More specific premise)
Therefore, Bella has hooves. (Very specific conclusion)
If the premise that all horses have hooves is true, and if Bella is, in fact, a horse, then it must be true that Bella has hooves. The same holds true for all examples of deductive reasoning. Here’s another example:
All who take the GMAT must work through a quantitative section. (General premise)
You’re taking the GMAT. (More specific premise)
Therefore, you have to work through a quantitative section. (Very specific conclusion)
This example shows the relationship between the truth of the premises and that of the conclusion. The first premise is categorically true: The GMAT requires you to work through a quantitative section. The second premise, however, may not be true. Certainly, you’re thinking of taking the GMAT or you wouldn’t be reading this book, but you may still decide not to take the test. This possibility doesn’t affect the logic of the argument. Remember, in deductive reasoning, the conclusion must be true if the premises are true. If you take the test, you have to work through a quantitative section, so this argument is valid.
When you analyze deductive reasoning arguments for the GMAT, the only way you can prove that a conclusion is true is by showing that all premises are true. The only way to prove that a deductive reasoning conclusion is false is to show that at least one of the premises is false.
In deductive reasoning, you draw a specific conclusion from general premises. With inductive reasoning, you do just the opposite; you develop a general conclusion from specific premises or observations. Inductive reasoning differs from deductive reasoning in that the conclusion in an inductive reasoning argument could be false even if all the premises are true. With inductive reasoning, the conclusion is essentially your best guess. That’s because an inductive reasoning argument relies on less complete information than deductive reasoning does.
Consider this example of an inductive argument:
Bella is a horse and has hooves. (Specific premise)
Smoky is a horse and has hooves. (Specific premise)
Nutmeg is a horse and has hooves. (Specific premise)
Shadow is a horse and has hooves. (Specific premise)
Therefore, it is likely that all horses have hooves. (General conclusion)
Because inductive reasoning derives general conclusions from specific examples, you can’t come up with a statement that “must be true.” The best you can say, even if all the premises are true, is that the conclusion can be or is likely to be true.
When you were growing up, you probably experienced social groups or cliques. These groups were often defined by shared interests, behaviors, or backgrounds. Some of the common groups included those who enjoyed sports, those who were more laid-back, those who excelled academically (that was your group!), and various other categories. These labels were helpful because they gave you clues that allowed you to better understand how to interact with someone who was a member of a particular group. For instance, you likely knew better than to pick a fight with a talented athlete, and you might have found it easy to bond with an individual who was laid-back. Well, we categorize GMAT questions for the same reason. After you figure out a critical reasoning question’s type, you know just how to deal with it. Most of the critical reasoning questions you’ll encounter on the GMAT fit into one of the following five categories:
Because each question type has a best way to handle it, recognizing what type of question you’re dealing with before you try to answer it is important. That’s why you read the question before you tackle the argument. You’ll immediately know what you need to look for when you read the argument from the wording of the question.
Some GMAT critical reasoning questions ask you to identify a premise that isn’t there. For these types of questions, the author directly states a series of premises and provides a clear conclusion, but in getting to that conclusion, the author assumes information. Your job is to figure out what the author assumes to be true but doesn’t state directly in drawing the conclusion to the argument. Seeking-assumptions questions may look like these:
Words like assume, rely, presuppose, depend on, and their derivatives usually indicate seeking-assumptions questions. Remember, these questions ask you to look for the ideas the author relies on but doesn’t state.
As you read seeking-assumptions questions, look for information that’s necessary to the argument but isn’t stated by the author. In these questions, the author always takes for granted something on which the entire argument depends. You just need to identify what that is. To do so effectively, choose an answer that links the existing premises to the conclusion. The assumption you’re seeking always bears directly on the conclusion and ties in with one or more premises, often with the last premise. Therefore, the best answer often contains information from both the last premise and the conclusion.
For example:
Women receive fewer speeding tickets than men do. Women also have lower car insurance rates. It is clear that women are better drivers than men.
The preceding conclusion is based on which of the following assumptions?
I. Men and women drive cars equal distances and with equal frequency. II. Having lower car insurance rates indicates that one is a better driver than those who have higher rates. III. Speeding tickets are equally awarded for violations without any gender bias on the part of police officers.
As always, read the question first. Because it references assumptions, we bet you figured out pretty quickly that it’s a seeking-assumptions question.
Next, read through the argument and try to figure out the assumption or assumptions the author makes in reaching the conclusion that women are better drivers. The author moves from the premises to the conclusion pretty quickly and assumes that fewer speeding tickets and lower car insurance rates indicate better driving skills. The author also assumes that men and women have equal driving experiences. Use this information to examine each of your options.
Look at Statement I first. It fits with your second observation that men and women experience equal driving situations, so eliminate any answer choices that don’t include Statement I. This means that you can get rid of Choices (B) and (D), which leaves you with Choices (A), (C), and (E).
Before you continue reading through your options, examine the remaining answer choices. You’ll see that it’s best to examine Statement II next, because if it’s true, you won’t even have to read Statement III; you’ll know the answer is Choice (E). You have to read Statement III only if you determine that Statement II isn’t an assumption.
The information in Statement II links the author’s last premise, that women have lower insurance rates, to the conclusion that women are better drivers. Thus, Statement II is also correct. You can eliminate Choices (A) and (C), and by process of elimination, the answer must be Choice (E).
If you read through Statement III, you’ll confirm that it, too, is an assumption the author makes about men and women having an equal playing field in the driving game.
If you find seeking-assumption questions to be tricky, try arguing the opposite position. For example, in the sample question, you could’ve taken the opposing view, that men are better drivers. This means you’ll be looking for ways to undermine the conclusion. If you assume the premises to be true, the best way to attack the conclusion is to show that the author assumes things that aren’t true. For example, you may argue that men have more accidents because they drive more, they get more tickets because police are less forgiving with male speeders, and they have higher car insurance rates because they drive more-expensive cars. Those counterarguments expose the author’s assumptions.