How to Attack Critical Reasoning Arguments

September 7, 2011
Bret Ruber

When you encounter an assumption, strengthen, weaken or flaw critical reasoning problem – and remember, these question types account for well over half of all critical reasoning – you will need to break down the argument that the stimulus makes.  Luckily, every GMAT argument is made up of the same three basic components: the conclusion, the evidence and the central assumption.

Your first step is always to identify the conclusion.  The conclusion is the author’s main point – it is the whole reason the author wrote the argument.  You have a couple options for finding the conclusion.  First, you can look for conclusion keywords, such as “therefore” and “thus.”  If you see a conclusion keyword, what follows must be the conclusion.  Second, you can ask yourself, “If I wanted to get rid of everything in this argument, except one sentence, but I still wanted the argument to make the same point, which sentence would I keep?”  The sentence you would keep is the conclusion.

Once you have found your conclusion, you should identify the evidence.  The evidence is any information the author includes that supports the conclusion.  While the evidence is often factual, such as evidence based on polls or surveys, it can also be conjecture.

Finally, you need to find the central assumption.  The assumption is an unstated piece of information that must be true for the evidence to lead to the conclusion.  In other words, if you were to find out the assumption was false, that would cause the entire argument to fall apart.  In order to figure out the assumption, you should look for any information that shows up in the conclusion, but not the evidence.  The assumption must address this new information in some way.

For example, let’s say you have an argument that says hamburgers are delicious, therefore restaurant X has delicious food.  The conclusion is that restaurant X has delicious food and the evidence is that hamburgers are delicious.  The assumption of this argument is that restaurant X serves hamburgers.  While this is unstated, it must be true for the evidence, which pertains to hamburgers, to logically lead to the conclusion, which pertains to restaurant X.

Whenever you practice critical reasoning make sure to practice the steps outlined above and you will be well on your way to answering critical reasoning argument questions correctly.

Bret Ruber Bret has been teaching for Kaplan since 2005, and has helped over 1000 students with their GMAT preparation. He spent three years teaching in Manhattan, where he served as an Elite Teacher and a full-time instructor, before moving to London, where he is now the GMAT Master Teacher for Kaplan’s London Center. As the GMAT Master Teacher, Bret trains, observes and mentors teachers, in addition to continuing his own teaching and tutoring, and has taught courses across Europe, including Italy, Ireland, and Germany. Bret contributes to Kaplan’s GMAT curriculum on an on-going basis, and was also a contributor to Kaplan's 2010 GMAT course.

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