GMAT Critical Reasoning: How to See the Structure behind the Words

Written by Kelly Granson. Posted in GMAT Study Guide

In this article, we will focus on working with critical reasoning (CR) arguments. GMAT Critical Reasoning questions require a very precise understanding of an argument's structure. No matter how well versed you may be in tips and tricks for handling particular question types or working with answer choices, missing or misunderstanding something in the argument itself substantially reduces your chances of getting the question right.

Why is it such a challenge to get a clear picture of the structure of an argument? Problems with understanding CR arguments often lie in their complex language. Therefore, regardless of what you are asked to do with the argument—identify missing premises, spot a logical fallacy, or reach a further conclusion—first you must strip the argument of unnecessary words to expose its structure. Here's how you do that.

Step 1: Identify the parts of the argument. Typically, a CR argument features a conclusion that rests on certain premises. Start "untangling" the argument by finding the conclusion. It might be hinted at in the question, it might contain a signal word, or it might feature no indicators at all but simply take the form of a claim, a subjective opinion of the author. Once you have found the conclusion, look for the premises, which will explain why the author thinks so.

Step 2: Understand what the parts you have identified actually mean. Paraphrase the conclusion and the premises using your own words. Simplify the sentences as much as possible, so that you can diagram the argument.

Step 3: Make a diagram of the argument using your simplified premise(s) and conclusion. You can devise your own system of symbols and abbreviations, and then stick to it to avoid confusing yourself. The purpose of diagramming arguments is twofold. (a) Having a diagram actually saves time. Instead of rereading the whole argument, you can just glance at a diagram. (b) Diagramming helps you focus, and it makes reading under pressure easier. As you become more proficient in CR, you will come across arguments that can be solved easily without making a diagram; whenever an argument seems obscure, however, an attempt to write it down in schematic form will always make you more aware of its structure.

Step 4: Your further actions depend on the specific question type.

Let's see how this can be applied to real CR arguments.

Example 1 (Official Guide 12th Ed., Question 50)

Although computers can enhance people's ability to communicate, computer games are a cause of underdeveloped communication skills in children. After-school hours spent playing computer games are hours not spent talking with people. Therefore, children who spend all their spare time playing these games have less experience in interpersonal communication than other children have.

The argument depends on which of the following assumptions?

(A) Passive activities such as watching television and listening to music do not hinder the development of communication skills in children.

(B) Most children have other opportunities,in addition to after-school hours, in which they can choose whether to play computer games or to interact with other people.

(C) Children who do not spend all of their afterschool hours playing computer games spend at least some of that time talking with other people.

(D) Formal instruction contributes little or nothing to children's acquisition of communication skills.

(E) The mental skills developed through playing computer games do not contribute significantly to children's intellectual development.

From reading the question, we infer that the argument necessarily contains a conclusion: after all, an assumption is what the author makes when reaching a conclusion. The first statement does sound quite subjective, so it might very well be the conclusion. The second statement looks more like something the author takes for granted, so most likely it is a premise. The last sentence contains the signal word "therefore," which leaves no doubt regarding its conclusive nature. Now we've found our conclusion and one premise. We do not need to concern ourselves with the first sentence; it presents a wider point of view in whose favor the author is trying to reason. How do we turn this argument into a neat diagram?

In the premise, the subject is hours spent playing. The predicate is are hours not spent talking. The relationship between subject and predicate is that of equivalency. The rest of the sentence is just extra words when it comes to diagramming the structure of the argument. What's essential is playing = not talking. If we break down the conclusion, it states:

1) There are kids who play computer games.

2) There are kids who don't play computer games.

3) Both groups have certain experience in interpersonal communication.

4) The interpersonal experience of kids who play is less than that of kids who don't play.

Simplifying the language might leave us with a statement along the lines of

playing kids talk < other kids talk.

Premise: playing = no talking

Conclusion: playing kids talk < other kids talk

Now that we have reduced the argument to schematic form, it is much easier to find an assumption, i.e. to see what is missing, to see what else must be true in order for this conclusion to be true. Obviously, we need to know more about how kids who do not play computer games spend their time. Only if they do devote at least some of it to talking will our conclusion be true. Answer choice (C) provides this necessary condition.

Example 2 (Official Guide 12th ed., Question 91)

Environmentalist: The commissioner of the Fish and Game Authority would have the public believe that increases in the number of marine fish caught demonstrate that this resource is no longer endangered. This is a specious argument, as unsound as it would be to assert that the ever-increasing rate at which rain forests are being cut down demonstrates a lack of danger to that resource. The real cause of the increased fish-catch is a greater efficiency in using technologies that deplete resources.

The environmentalist's statements, if true, best support which of the following as a conclusion?

(A) The use of technology is the reason for the increasing encroachment of people on nature.

(B) It is possible to determine how many fish are in the sea in some way other than by catching fish.

(C) The proportion of marine fish that are caught is as high as the proportion of rain forest trees that are cut down each year.

(D) Modern technologies waste resources by catching inedible fish.

(E) Marine fish continue to be an endangered resource.

Since the question asks for a conclusion, there is no need to look for one in the argument. Let's just examine each statement in turn and simplify it. The first sentence can be broken down into two clauses:

1) The commissioner (C) wants the public to believe that

2) If more fish are caught, it is because fish are no longer in danger.

C: ↑fish caught ← no danger

The second sentence lets us know that the environmentalist (E) does not agree; he thinks this argument is unsound. In other words, E thinks that if more fish are caught, it does not mean that the resource is no longer in danger (E: ↑fish caught -/-> no danger) To prove his point, he makes an analogy with rain forests, claiming that it is unsound to believe that if more rain forests are cut down, it means that there is no danger to that resource. To claim "it is wrong that X is caused by Y" is to claim that X is not caused by Y, so E: ↑RF cut -/-> no danger.

Finally, in the last sentence, the author presents what he believes to be the real cause of the increase in the number of fish caught: technological advances. This can be written as E: ↑fish caught ← ↑use of tech

Now we have reduced our argument to the following:

C: ↑fish caught ← no danger

E: ↑fish caught -/-> no danger


↑RF cut -/-> no danger


↑fish caught ← ↑use of tech

Now we need to identify the answer that follows from or at least does not contradict the information above. This would be Choice E, since the information in the argument is not sufficient to support any other choice.

Closely looking at each sentence might seem time-consuming, especially in the beginning. It will get much faster with practice, however, and it is the cornerstone of successful critical reasoning.

In summary, the way to handle critical reasoning questions is to:

1. Identify parts of the argument.

2. Simplify each relevant sentence.

3. Diagram the relationship between the subject and the predicate.

4. Pick the right answer!


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