Critical Reasoning - An Overview by Stephen Bolton, 11th March, 1999

Critical Reasoning questions are one third of the Verbal section of the GMAT exam. These questions are designed to test one's logic and reasoning skills, particularly in evaluating arguments. The questions themselves could deal with almost any subject matter, and no familiarity with that subject matter is assumed or required.
This tutorial aims to give you the tools to find the answer that ETS wnat you to find which is just what you need to raise your score.

The GMAT's Critical Reasoning is intended to be an effective way of evaluating how people reason. However, the truth is that the logic in many of the questions is less than completely sound. There is definitely room for interpretation on many of these questions, judging from many examples taken from old GMAT tests. But there is little you can do about that - they make up the questions, they make up the rules.
You could cry about it. Go ahead, have a good cry. We will wait.
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Feel better? Good. Now let's take a look at how we can best this test to obtain the best score we possibly can.
A Critical Reasoning Problem is comprised of three main parts: the text, the question, and the five answer choices. We will deal with the different types of questions later.

Here's an example of a Critical Reasoning text: A CEO of a major company noted a serious decline in worker productivity during the previous five years. According to a report done by an outside consultant, productivity dropped by 35% by the end of that period. The CEO has therefore initiated a plan to boost productivity by giving employees shares of the company as part of their pay package.
We can use the text above to show the four different parts of a Critical Reasoning text.
Conclusion/Main Idea - Most problems have a central idea or thesis. This is almost always located in the sentence at the beginning of the text, or in the sentence at the very end. In this case, it is at the end of the passage: The CEO has therefore initiated a plan to boost productivity by giving employees shares of the company as part of their pay package.
Notice the word therefore in that sentence. Words like therefore, thus, hence, and so usually tell us that this is the conclusion or the main idea. Let these words lead you to the main idea.
Premise - Premises are the facts or evidence that support or lead to the conclusion. Unlike assumptions, they are explicit. Here is an example from the text: A CEO of a major company noted a serious decline in worker productivity during the previous five years.
This premise helps the author lead to the conclusion or main idea of the text.
Assumption- Assumptions are the facts that support the conclusion, like the premise does, but unlike the conclusion and premises they are not stated in the text: they are implicit. Here is what would be an example of an assumption for this particular Critical Reasoning problem: Owning something or part of something obliges you work harder to make it succeed.
Note that this line is not in the text: it cannot be in the text if it is an assumption of the author. But it does give the argument as a whole some sense, and also supports the conclusion.
Supporting Information- Like a premise, this is stated and explicit information embedded in the text, but unlike a premise, it does not support the conclusion. At best it supports a premise or provides further detail or information regarding a premise. From the text: According to a report done by an outside consultant, productivity dropped by 35% by the end of that period.
This sentence supports the first sentence, the premise that notes that productivity has dropped. Supporting Information does not support the Conclusion or Main Idea, rather, it supports information that is already in the text.

The following strategies should help you with all the Critical Reasoning questions. 1. KISS - Remember the old saying, Keep It Simple Stupid i.e. KISS? It also applies to Critical Reasoning. The key to Critical Reasoning is to focus on what the question is asking you to do, finding an answer choice that best answers the question. THAT'S ALL YOU SHOULD DO. Some books tell you to think of the 'scope' or 'parameters' of the argument. That's valid too – it is basically saying the same thing. Just answer the question, do not read too much into it or let your own knowledge of a subject lead you to pick the wrong answer. KISS.

2. Patterns - Look for particular types of questions, and then use the strategies appropriate for that type of question to choose the right answer. We will be looking at different types of Critical Reasoning Questions in the next section.

3. Identify the Argument - Sounds obvious? Nonetheless, many forget or do not know the importance of carrying out this absolutely essential task. In order to do this, imagine what would satisfy the question. After you have imagined what could satisfy the question, look for it down below in the five answer choices. Is it right there, or very similar to it, in answer choice B, for example? If so, then B probably is the answer. Read the other answer choices quickly, but this is probably the right answer. This strategy saves you some valuable time.

Of course, this strategy does not apply to Supply the Conclusion questions, but it does especially matter for Weaken, Strengthen, Continue the Idea and