GMAT Critical Reasoning

What Critical Reasoning tests

Critical Reasoning (CR) is part of the GMAT Verbal Reasoning section. A prompt usually presents a compact argument and asks you to evaluate it. You are not asked whether you agree with the policy or whether the conclusion is sensible in real life. Your task is to use the information in the prompt and answer the specific logical question.

The recurring structure is evidence followed by a conclusion. The author may assume that a relationship will continue, that a sample represents a larger group, or that one cause explains an observed change. Your job is to find the gap the question targets. If the question asks for a conclusion from facts, do not invent an assumption that the facts do not support.

Map the argument before reading choices

Read the final claim and ask what the author wants you to believe. That is usually the conclusion. Then identify the observations or reasons offered in support. A sentence beginning with 'therefore' may mark the conclusion, but arguments do not always use signpost words. Summarize the reasoning in a few words before looking at the options.

Suppose a store added evening hours and monthly sales rose. The evidence is that evening hours were added and sales rose. The conclusion might be that evening hours caused the increase. The gap is that no other explanation is ruled out, such as a seasonal promotion or a new product. Recognizing the causal leap helps predict what would strengthen or weaken the claim.

Separate facts from the author's interpretation. A prompt may say that customers surveyed preferred shorter lines, then conclude that a proposed staffing change will increase satisfaction. The preference is evidence; the staffing prediction is an inference. A choice that merely repeats the survey result does not necessarily support the prediction.

Match the task

Before evaluating answer choices, restate the task. 'Strengthen' means make the conclusion more credible, not prove it beyond all doubt. 'Weaken' means reduce support, not necessarily prove the conclusion false. A necessary assumption is a statement the argument depends on. An inference question asks what must or is best supported by the information rather than what would make a persuasive argument.

Strengthen and weaken with the gap

A strengthen answer often confirms the missing connection. If a company concludes that a new training program reduced errors because the error rate fell afterward, evidence that no other policy or staffing change occurred makes the causal inference stronger. A fact that merely says employees liked the training may be positive but does not establish that errors fell because of it.

A weaken answer can offer an alternative cause, show that the evidence is unrepresentative or reveal an exception. It need not prove the conclusion wrong. If the question asks whether a bus lane reduced total commute time, evidence that bus riders saved five minutes while car commuters lost twelve minutes weakens a broad conclusion about all commuters.

Be precise about scope. If an argument concludes that all branches improved, evidence about one branch may not be enough to strengthen it substantially. If a conclusion concerns average customer satisfaction, one unhappy customer does not settle the issue. Match the population and outcome in the conclusion.

Assumptions and negation

An assumption connects evidence to the conclusion. To test a candidate necessary assumption, negate it and ask whether the argument loses its support. If an answer choice says that no competing policy caused the sales increase, its negation says a competing policy did cause it. That would undermine the causal argument, so the assumption may be necessary.

Negation is a diagnostic, not a substitute for understanding the question. A strengthen choice can be useful without being necessary. For example, evidence that customers noticed the new packaging may strengthen a sales argument, but the argument could remain plausible if some customers did not notice it. The task wording determines whether necessity matters.

Original worked examples

Weaken a causal conclusion

A city installed brighter lamps on a residential street. Reports of nighttime theft fell during the next month, so the city concludes that brighter lamps reduced theft. Which fact most weakens the conclusion? During that month, police also increased patrols on the same street. This gives an alternative explanation for the decline, weakening the claim that lighting caused it.

A choice saying residents liked the lamps does not address theft. A choice saying the lamps use less electricity than older ones concerns operating cost. A choice saying reports fell on several streets without lighting changes might strengthen the lighting theory, depending on the comparative data. The strongest answer targets the causal link in the conclusion.

Find a necessary assumption

A bakery plans to open an hour earlier because survey respondents said they would buy breakfast there. The owner predicts the change will increase daily profit. Which assumption is required? The additional sales must generate enough revenue to cover the added labor and operating costs. Without that condition, more customers could arrive while profit still falls.

The assumption is not that every survey respondent will become a regular customer. Some can fail to follow through and the plan could still work. Nor must breakfast items be the bakery's highest-margin products. The needed condition concerns whether incremental profit exceeds incremental cost.

Draw an inference

A firm requires every new analyst to complete a statistics course. Some analysts who completed the course later joined the research team. What follows? At least some research-team analysts completed the statistics course. The statements do not establish that every analyst joined research or that the course caused the transfer.

A plausible choice that the course improved performance goes beyond the facts. An inference answer should remain inside what the premises support. Words such as all, only, most and some carry logical force, so preserve them carefully.

Eliminate attractive distractors

Wrong choices often sound relevant while answering a different question. One may repeat a premise, discuss the same topic without affecting the argument, reverse cause and effect, or make an extreme claim. A useful check is to insert the choice into the argument and state how it changes the support for the conclusion.

For strengthen and weaken questions, ask whether the choice changes evidence, the reasoning link or an assumption. For an inference question, ask whether the choice is guaranteed by the facts. For an assumption question, test necessity. This small shift in method prevents a choice that feels persuasive from winning merely because it uses familiar words.

Avoid importing personal knowledge. A prompt about a product, scientific study or economic policy may describe a simplified situation. Use the provided facts unless a question explicitly asks for an outside concept. Inference questions especially reward restraint: an answer that is realistic can still be unsupported.

Pacing and practice

The GMAT Verbal section has 23 questions in 45 minutes, mixing Critical Reasoning and Reading Comprehension. Do not assume every CR question deserves the same amount of time. A short argument may resolve quickly; a dense prompt may require careful mapping. If you are stuck between two choices, identify the task and compare how each affects the conclusion, then make a decision and move on.

Practice in stages. First, untimed, label the conclusion and evidence and explain why each answer fits or fails. Next, use short timed sets to build decision speed. Finally, mix CR with Reading Comprehension so you have to switch between argument analysis and passage reading. Review correct answers you guessed as well as misses.

Keep an error log with task type, gap, chosen distractor and correction. If you often miss assumption questions, practice separating necessary assumptions from helpful evidence. If you miss causal arguments, list possible alternative explanations. If you choose extreme inference answers, mark the word that exceeds the premises. Then solve fresh questions to test the correction.

A useful review session revisits the argument without answer choices first. State its evidence and conclusion in your own words, then describe the missing link. Only after that, compare the options. This prevents the wording of a tempting choice from reshaping your understanding of the prompt. When the correct answer seems surprising, explain why the argument needs it instead of memorizing its phrasing.