GMAT Critical Reasoning questions often revolve around weakening, strengthening, or finding assumptions in an argument. Being able to quickly deconstruct the argument into its logical components—a process known as the logic chain—can dramatically improve accuracy and speed.
The Logic Chain Method
Every argument consists of premises (evidence) and a conclusion. The logic chain is the reasoning that connects the premises to the conclusion. To weaken or strengthen an argument, you must identify this chain and then find an answer choice that either breaks or reinforces it.
Steps for the logic chain method:
- Identify the conclusion—the main point the author is making.
- Identify the premises—the evidence given to support the conclusion.
- Determine the assumption—the unstated link between the premises and the conclusion.
- For weaken questions, find an answer that attacks this link or shows that the premises do not lead to the conclusion. For strengthen questions, find an answer that supports the link or eliminates an alternative cause.
Weaken Questions
Weaken questions ask you to undermine the argument. The correct answer will typically attack the assumption or introduce new evidence that makes the conclusion less likely.
Example from an official GMAT question: Argument: A company plans to require all employees to attend a training program to improve productivity. The program has been successful at other companies, so the company will see similar improvements.
- Conclusion: The company will see improvements in productivity.
- Premise: The program was successful at other companies.
- Assumption: The factors that made the program successful elsewhere apply to this company.
To weaken, we need an answer that breaks this assumption. For instance: “The other companies had a different organizational structure that was more conducive to the training methods used.”
Strengthen Questions
Strengthen questions ask you to support the argument. The correct answer will often rule out alternative explanations or provide additional evidence that makes the conclusion more probable.
Example from an official GMAT question: Argument: A city saw a decrease in crime after implementing a new policing strategy. Therefore, the strategy was effective in reducing crime.
- Conclusion: The strategy caused the crime reduction.
- Premise: Crime went down after the strategy was implemented.
- Assumption: No other factors caused the crime reduction.
A strengthen answer could be: “During the same period, neighboring cities with no new strategies experienced stable or increasing crime rates.” This rules out a common external cause.
Assumption Questions
Assumption questions ask you to identify the unstated premise that must be true for the argument to hold. The correct answer is a necessary condition for the conclusion.
Example from an official GMAT question: Argument: The school board argues that increasing the number of teachers will improve student performance, because more teachers allow for smaller class sizes.
- Conclusion: Increasing teachers will improve student performance.
- Premise: More teachers allow smaller class sizes.
- Assumption: Smaller class sizes actually lead to improved student performance.
The correct answer will state something like: “Smaller class sizes result in more individualized attention, which improves performance.”
Applying the Logic Chain to Official Questions
Practice with official GMAT Critical Reasoning questions is key. For each question, write down the conclusion, premises, and assumption. Then, for weaken and strengthen questions, prephrase an answer that attacks or supports the assumption before looking at the choices. This prevents you from being swayed by tempting but irrelevant options.
Common trap answers:
- Out of scope: choices that address a related topic but not the specific argument.
- Opposite: choices that do the reverse of what is asked (e.g., strengthen when you need to weaken).
- Extreme language: choices with words like “all” or “never” that are too strong for the argument.
By consistently using the logic chain, you’ll find that the correct answer becomes more apparent, and you’ll avoid common pitfalls.
FAQ
What is the most important step in the logic chain method? Identifying the conclusion and the assumption is crucial. The assumption is the gap that correct answers for weaken, strengthen, and assumption questions will address.
How do I differentiate between weaken and strengthen questions? Read the question stem carefully: “Which of the following, if true, most seriously weakens the argument?” versus “Which of the following, if true, most strengthens the argument?” Focus on the direction required.
Can I use the logic chain for other question types? Yes. While especially useful for weaken, strengthen, and assumption, understanding the argument’s structure is also helpful for flaw, evaluate, and inference questions.
Where can I find more practice with official GMAT questions? The GMAT Official Guide and the online question bank from the test maker provide authentic practice that mirrors the exam.