An Introduction to GMAT Critical Reasoning by Brian McElroy

Critical Reasoning questions are essentially logic games. The question stem consists of an Argument, which is a Conclusion supported by Evidence (also called the Premise). For each CR question, force yourself to identify / write down the Conclusion and the Premise (Evidence).

How do you identify the Evidence and the Conclusion? Easy. For example, if I say, “Because A, B,” then A is my Evidence and B is my Conclusion.

Your job as a test-taker is to try to “get inside” the argument and focus on the Inference: that which connects the Evidence to the Conclusion.

Consider the main CR question types:

1) Strengthen: in this case you want to make the conclusion stronger, either by eliminating an alternate explanation or strengthening the original premise.
2) Weaken: for these questions you want to make the conclusion weaker, in most cases by proposing an alternate explanation, or by weakening the original premise.
3) Assumption: asks you to find the assumption in the argument. Think of the assumption as “the thing you need to be true for the argument to work.” You can also try the “Assumption Negation Technique” for these questions: negate the assumption, and ask yourself whether this disproves the argument. If so, then you have found the assumption.
4) Flaw: asks you to find the flaw in the argument.
5) Logical Completion-Inference/Must be True/Most Supported: these are all variations on the same type of question. They are essentially Critical Reasoning questions that are lacking a conclusion (the answer is the conclusion itself).
6) Main Idea/Conclusion: exactly what it sounds like.
7) Fill in the Blank: exactly what it sounds like.
8) Role: typically selects sentences from the passage and asks about their overall role in the argument, such as the evidence, the conclusion, and the “intermediate conclusion”.

Other question types: Additional Evidence, Cause and Effect, Evaluate Argument, Except, Method of Reasoning, Resolve Paradox, Similar Reasoning.

In order to succeed on CR questions, you must be intimately familiar with the trap answer types: pre-evidence, out of scope, and post-conclusion (I invented the first and last terms, so don’t expect to find them elsewhere).

1) Pre-Evidence trap answers are answers that don’t change or render less effective the evidence cited in the argument (or the conclusion itself, of course).

2) Out of Scope trap answers are answers that aren’t directly relevant to the evidence, inference, and/or conclusion.

3) Post-Conclusion trap answers are answers that don’t directly affect the conclusion, or in some cases even acknowledge the conclusion.

4) Splitting Hairs trap answers tell us something that we already know in a basic sense, in a more detailed way, one that doesn’t affect the main conclusion in any significant manner.

For example, if I were to write “Since it is cold outside, you should wear a hat to protect your head.” and then ask you to weaken this argument...

A Pre-Evidence trap answer would be something like “It isn’t usually cold in this part of the country at this time of year.” Well, who cares? It is cold now, and we are trying to deal with it.

An Out of Scope trap answer would be something like “Hats aren’t fashionable.” It might seem related because of the mention of hats, but it’s not directly tied to the connection between hats and warmth. Fashion is not our concern here--it's protecting our heads from the cold weather.

A Post-Conclusion trap answer would be something like “Even if you wear a hat, you will still need warm boots for your feet.” Well, that might be true, but it has nothing to do with whether hats are effective at protecting your head from the elements. Plus, this answer has already acknowledged our conclusion!

A Splitting Hairs trap answer would say something like “wearing a hat is only the 2nd most effective way to stay warm, according to scientists.” That might indeed be true—nor can we dispute the veracity of / “fact check” any claim on the GMAT—but this more detailed information about hats does not ultimately change the fact that hats still protect well against the cold.