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GMAT Critical Reasoning – The Foundation of the Exam

Chris Kane

Chris Kane - Menlo Coaching

Chris Kane is a mba.com Featured Contributor.

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No skill is assessed more on the GMAT than critical thinking. In one form or another, every question type – from Sentence Correction to Problem Solving – is cleverly evaluating your ability to remain critical and find flaws in your own approach to a question or within the information provided in that question. Why? Because the best managers and business executives are those who can quickly isolate problems and fix them efficiently and effectively.

The Critical Reasoning question type is, of course, the ultimate assessment of this essential business skill. GMAT Critical Reasoning questions are designed to evaluate a specific set of attributes relating to logic, and most students preparing for the test have never been exposed to this type of argument analysis. Broadly speaking, there are 3 types of Critical Reasoning questions you will encounter on the GMAT Verbal section:

  1. Those in which you must attack a given argument or plan (called the stimulus) and then find the answer choice that exposes a flaw or improves a flaw within that stimulus.
  2. Those in which you must analyze and describe the line of reasoning used within the stimulus.
  3. Those in which you must supply a valid conclusion based on the information given in the stimulus.

For type 1 questions, there are several important subtypes that you will see described by test prep companies: strengthen, weaken, assumption, useful to evaluate, and explain the paradox. Type 2 questions are most commonly called method of reasoning questions (usually boldfaced questions), and type 3 are commonly referred to as inference or conclusion questions. Note: well over 75% of the Critical Reasoning GMAT questions you will see on your exam are type 1, so we will focus mainly on the strategies for that common type in this article.

Best Practices for GMAT Critical Reasoning

To succeed in Critical Reasoning, you must develop a structured set of best practices that help you quickly maneuver through the different tricks and traps you will encounter on these questions. Some of these tips, such as reading the question stem first, are universal across different test prep curricula, while others are more sophisticated.

1. Read the Question Stem First

Since the mindset and strategies required for these three types of Critical Reasoning questions (and even between the subtypes in category 1) are so different, it is essential that you read the question stem first to determine which type of question you are facing. As an example, consider the following two question stems, which can easily be confused:

  • Which of the following most supports the argument above?
  • Which of the following is most supported by the argument above?

In the first question stem, you are dealing with a strengthen question. You need to attack the given argument or plan and then find a new piece of information in the five answer choices that necessarily improves the given argument or plan.

In the second question stem, your approach is completely different! You take everything in the stimulus as fact, and then determine which of the answer choices is a valid conclusion based on that given information.

If you don’t read the question stem first, you are wasting valuable seconds in your initial reading of the given stimulus because you don’t know your goal, and you will thus face time pressure on the verbal section. Additionally, if you don’t categorize the question correctly, you are doomed to get it wrong, and GMAT question writers purposefully make this task difficult.

2. Master the Art of Deconstructing Arguments

Another core skill tested on the GMAT is your ability to contend with abstract presentation of information and concepts. Many Critical Reasoning questions contain extremely complicated arguments that are both abstract and difficult to comprehend.

One of the big mistakes students make in attacking Critical Reasoning questions is that they go to answer choices before they fully deconstruct and understand the given stimulus. Piling on additional information to something you don’t fully understand is a common mistake students make on the GMAT generally – don’t go to answer choices until you understand the given information and the goal of the question!

In our Menlo Coaching GMAT curriculum, we put a huge emphasis on teaching students how to properly deconstruct arguments. This is best done by reading the full argument (for type 1 and type 2 questions, in which you are presented with a full argument in the question stem) and then isolating the conclusion. To make sure you have actually found the proper conclusion, you “Ask Why?” to that conclusion and see if the question leads back to the premises within the argument. Once you have done all of this properly and fully understand the given stimulus, you should then move to the next step in your structured best practices.

3. Attack (and Anticipate)!

So at this point, you have categorized the question type and fully deconstructed the given stimulus; now the real game of GMAT Critical Reasoning begins!

For all type 1 questions, you will have a full argument or plan in the stimulus, and you need to attack that stimulus, finding any flaws or common fallacies within the line of reasoning. In 20 years of preparing students for this question type, I have noticed one universal attribute among the “masters” of GMAT Critical Reasoning: they find the flaws on their own first and then evaluate the answer choices. To some this may seem counterintuitive (shouldn’t you leverage the answers first?), but the reality for all type 1 questions is that the answer choices are more your enemy than your friend.

In general on the GMAT, an essential best practice is to leverage all answer choices and use them actively, but Critical Reasoning answer choices are notoriously manipulative. Incorrect answers tempt you with ideas and “flaws” that pollute your brain and keep you from isolating the true issues in the argument. By attacking the argument before digging into answers, you are in charge of finding the flaws (and you will hone this skill with lots of practice) and can avoid this “polluting of the mind” by clever incorrect answers.

When you do anticipate flaws in the stimulus (often called “pre-thinking” in test prep curricula), it is essential that you do so broadly: don’t anticipate exactly how the answer choices might relate to the flaw, but find the core issues in the argument that should be addressed within one of the answers, which often does so in an obtuse or confusing way. On the hardest type 1 questions, you will likely need to use some hints from the answers about what to consider in the stimulus, but you must do that carefully while you sort through a collection of tasty trap answers.

Importantly, this type of anticipation is really only used for type 1 questions. For method of reasoning questions, you will deconstruct the argument and perhaps find some flaws, but you need to use process of elimination and compare answers to see which one is accurately describing the argument or the boldfaced portions of that argument. For inference/conclusion questions, you cannot anticipate what valid conclusion the question writers might provide, so again you need to attack each answer choice using process of elimination until you find the one answer that is a valid conclusion.

In summary, if you want to improve accuracy and speed in GMAT Critical Reasoning, you must get comfortable attacking arguments on your own and recognizing the common logical fallacies found in these questions. In no particular order, here are some of the most common fallacies you will encounter in GMAT Critical Reasoning practice questions and on your exam:

  • Mistaking Correlation for Causation
  • Generalization
  • Numerical Data Flaws (using absolute number data when you should use percentage data, improper use of statistics, etc.)
  • Past Trends Don’t Guarantee Future Trends
  • Baseline Assumptions (forgetting about starting points and what might have been true in a previous time frame)

Make sure you understand these flaws deeply and get skilled at recognizing them in a variety of scenarios and presentations.

4. Analyze the Answers (and be ready for the more “sinister” tricks and traps in GMAT Critical Reasoning).

Now, you are fast at categorizing the question and deconstructing the stimulus. You have mastered the common logical fallacies used on GMAT Critical Reasoning questions and you are good at attacking arguments on your own. That means you will get most GMAT Critical Reasoning questions correct, right? Sadly, that is not enough!

The additional mechanisms used to make these questions hard are the most sinister and difficult to handle. These traps are mainly assessing who is paying careful attention to details and making sure their mind does not wander (again important skills in business!):

  • Wordplay. Wording scenarios and clever language construction are used to elicit misinterpretation and misreading by the test-taker. Often this involves negation or other forms of abstract wording.
  • Misdirection. Question writers insert captivating information (what I often call the “shiny penny”) to draw your focus away from what really matters, which may be quite boring..
  • Mental Inertia. This is a form of misdirection in which question writers use topics for which everyone has deeply preconceived notions, but the answer is contrary to what you expect.
  • Word Shifts. You will commonly see subtle word shifts that create gaps or flaws within an argument. As I joke in my classes, there is no such thing as “synonyms” in Critical Reasoning. If a word has been changed between premises or between premises and the conclusion, it is probably creating a gap within the argument.

Seeing through this type of difficulty and avoiding these common traps and tricks comes through doing lots of high quality official GMAT Critical Reasoning practice questions. After you get burned by these different cons enough times, you start to see the traps quickly and your percentile in GMAT Critical Reasoning will jump dramatically. Pattern recognition through completion of a high volume of official problems is essential to success in training for Critical Reasoning.

GMAT Critical Reasoning Practice Question

To conclude this article, let’s apply these best practices to one retired official Critical Reasoning question. Take around 2 minutes and try to solve the question on your own:

The program to control the entry of illegal drugs into the country was a failure in 1987. If the program had been successful, the wholesale price of most illegal drugs would not have dropped substantially in 1987.

The argument in the passage depends on which of the following assumptions?

A. The supply of illegal drugs dropped substantially in 1987.

B. The price paid for most illegal drugs by the average consumer did not drop substantially in 1987.

C. Domestic production of illegal drugs increased at a higher rate than did the entry of such drugs into the country.

D. The wholesale price of a few illegal drugs increased substantially in 1987.

E. A drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in their wholesale price.


This problem is a great example of the wordplay and misdirection that I highlighted previously. The argument itself isn’t that difficult to understand but the answers are manipulative and the wording tricky. Let’s apply all the previously discussed GMAT Critical Reasoning tips in a methodical way to find the correct answer:

  1. Categorize. The question is clearly an assumption question, a type of strengthen question in which you must isolate a necessary premise in the 5 answer choices. The correct answer will necessarily improve the quality of the argument.
  2. Deconstruct. Since this is a relatively short and simple argument, it is easy to deconstruct. You should first isolate the conclusion – ”The program to control entry of illegal drugs was a failure in 1987” – and then “ask why?” to build back any given premises. Why was it a failure? Because if it had been a success, the wholesale price would not have dropped substantially in 1987. As is often true in assumption questions, you must deal with negation both in the given argument and in some of the answer choices. To help better understand the argument, simplify the given premise using affirmative language (but be careful not to change the meaning!). “Because if the program had been a success, the price would have remained the same or gone up (or perhaps just dropped a little)”
  3. Attack and Anticipate. This argument presents a classic flaw in which alternative explanations are ignored. The argument relies on the idea that if the price went down substantially, it must have been because supply increased from the entry of illegal drugs and thus the program failed. But wait a second what else could have caused the price to drop substantially? If demand for illegal drugs dropped in 1987, then the price could have gone down even if the program was successfully preventing the entry of drugs. Alternatively, domestic production could have increased the supply of available drugs and the price could have gone down even with successful control of illegal entry from other countries. With those two flaws in mind, carefully assess the answers.
  4. Analyze the Answers (while looking out for wording tricks and more sinister traps).

(A) The correct answer should support the idea that the program was a failure. If anything, this statement does the opposite! If the supply dropped, then likely the program was a success, not a failure (but we don’t even know because the decrease in supply could have been related to domestic sources). On most strengthen questions, at least one trap answer will weaken the argument, particularly when negation is present, because test-takers get confused about their goal with the argument.

(B) This tricky incorrect answer contains the negation you often see in GMAT Critical Reasoning assumption questions. Another common Critical Reasoning tip you will see across most test prep curricula is the assumption-negation technique. In short, this technique can be used to deal with difficult negation in answer choices for assumption questions. If you negate an essential premise (which is the correct answer in an assumption question) then it should destroy the argument. This allows you to take any answer choice presented negatively and read it affirmatively to see if it destroys the argument. Let’s do that here:

The price paid for most illegal drugs by the average consumer did not drop substantially in 1987.

So if the price paid did go down, this supports the idea that the program was a failure! If it was correct, this negated version should destroy the argument. The human brain does not deal with negation well, so it is much easier to read answers like this affirmatively to see if they destroy the argument. Both of the first two answers are wrong essentially because they do the opposite of what they should. Also, you should note that this answer is about the price paid by consumers while the argument is using wholesale prices for its evidence a classic word shift!

(C) To make the argument that the program was a failure, you do not need to know that the domestic rate increased more than the foreign entry rate. The program would be a failure even if the domestic rate increase was less than the foreign entry rate increase. This comparison is irrelevant to the given conclusion but since it broadly addresses the domestic vs. foreign issue that you should have considered after your initial reading, some people will still pick it.

(D) The given argument involves “the wholesale price of most illegal drugs” while this answer just discusses a few illegal drugs. A few illegal drugs could increase while most drop with no effect on this argument. Note: if anything, this statement would again weaken the conclusion when we are trying to improve it. An increase in prices suggests the program might have been a success, not a failure.

Correct Answer

(E) Jackpot! Since this answer is presented negatively, let’s apply the assumption-negation technique and see if this destroys the argument.

A drop in demand for most illegal drugs in 1987 was not the sole cause of the drop in their wholesale price.

So, if a drop in demand WAS the sole cause of the drop in their wholesale price, this argument is completely destroyed because the price drop was not due to a failure of the drug entry program. This correct answer essentially removes a flaw, that if true, would be very problematic for the given conclusion.

Final Takeaways

To succeed in GMAT Critical Reasoning you need to follow a structured set of best practices. As you can see from this one example, the difficulty can be more from the negation and wording than from a difficult-to-find flaw or confusing argument. The most important skills to develop while training with official GMAT Critical Reasoning practice problems are the following:

  • Quickly be able to deconstruct and understand given arguments.
  • Attack arguments efficiently and be able to find all broad flaws within a line of reasoning on your own.
  • Learn how to contend with the difficult tricks and traps relating to wordplay and abstract presentation.

When those skills are mastered, you will see your CR percentile jump considerably AND you will be able to complete CR questions faster, allowing for less time pressure on the GMAT verbal section.

Chris Kane

Chris Kane - Menlo Coaching

Chris Kane is an mba.com Featured Contributor.