GMAT Critical Reasoning: Weakening, Strengthening, and Assumption Questions

Introduction to Critical Reasoning on the GMAT

The Critical Reasoning (CR) section of the GMAT tests your ability to evaluate arguments. Among the most common question types are those that ask you to weaken, strengthen, or identify an assumption. While each type has a distinct goal, they all require a clear understanding of the argument's structure.

The Logic-Chain Analysis Method

A practical approach to CR questions is to break the argument into a logic chain: premise → inference → conclusion. By identifying the premises and the conclusion, you can see the gaps or assumptions. Then, for strengthening, you look for information that supports the chain; for weakening, you look for information that breaks it; for assumption, you identify the unstated link that must hold.

Weakening Questions

Weakening questions ask you to find the answer choice that most undermines the argument. The correct choice often attacks an assumption or introduces information that makes the conclusion less likely. For example, if an argument concludes that a new policy will reduce costs, a weakening choice might show that the policy will increase other expenses, or that the premise used is not representative.

Strengthening Questions

Strengthening questions ask you to find the choice that makes the argument more likely to be true. This can be done by providing additional supporting evidence, eliminating a potential counterargument, or confirming a key assumption. The correct choice will directly support the link between premise and conclusion.

Assumption Questions

Assumption questions require you to identify the unstated premise that is necessary for the argument to hold. The correct answer is typically a statement that, if false, would destroy the argument. Use the negation test: if you negate the answer choice and the argument falls apart, then that choice is likely the assumption.

Applying the Method to Real GMAT Questions

To illustrate, consider a typical GMAT CR argument:

A city council plans to build a new highway to reduce traffic congestion. They argue that because the highway will create an additional route, congestion will decrease.

Using the logic chain, we see: premise (additional route) → conclusion (congestion will decrease). The unstated assumption is that drivers will use the new route, or that the new route will not attract new drivers. A weakening choice might show that the new highway will encourage more people to drive, thereby increasing overall traffic. A strengthening choice might show that the new route will specifically divert a large portion of current traffic. An assumption choice would be that the new route is usable in practice.

Conclusion

Mastering weakening, strengthening, and assumption questions requires consistent practice with the logic-chain analysis. By systematically identifying premises, conclusions, and gaps, you can improve accuracy and speed. For more detailed guidance and practice materials, you can consult independent study resources and official GMAT prep materials.

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