✓Identifying premises, conclusions, and unstated assumptions
✓Strengthen vs. Weaken question dynamics and causal fallacies
✓Boldface argument structure and role-of-sentence questions
✓Apparent discrepancies and resolving contradictory findings
High-Yield Test Day Strategies
•State the author’s exact conclusion in your own words before inspecting the options.
•For assumption questions, apply the Negation Test: if negating a choice breaks the conclusion, it is correct.
•In weaken questions, target the gap between premise and conclusion, not the factual premise itself.
Curriculum Benchmark
Sample Critical Reasoning & Arguments Questions
Step through verified problems with full mathematical rationales and trap analysis below:
Question 1Verbalcritical reasoning
Click an answer to check
A municipal health department reported that residents who regularly consume green tea have a 30% lower incidence of coronary artery disease than those who do not. The health director concluded that antioxidant polyphenols found in green tea provide direct cardiovascular protection and proposed subsidizing green tea purchases across public supermarkets.
Which of the following, if true, most seriously calls into question the health director’s recommendation?
Show Official Answer & Step-by-Step Rationale
Correct Answer:Individuals who regularly drink green tea are significantly more likely to engage in regular aerobic exercise and adhere to low-sodium diets than non-drinkers.
Step-by-Step Proof:
1. Deconstruct the argument:
- Premise: Green tea drinkers have 30% lower incidence of coronary disease.
- Conclusion: Green tea polyphenols directly provide the cardiovascular protection.
2. Flaw in reasoning: Correlation does not equal causation! The argument fails to consider a confounding third variable (healthy user bias).
3. Weakener evaluation:
- Choice B presents the classic confounding variable: green tea drinkers also exercise more and eat healthier diets. These lifestyle factors, rather than the green tea itself, could entirely explain the lower heart disease rates!
Choices A, C, D, and E are irrelevant to whether green tea was the causal agent of the cardiac benefits.
Common ETS Trap Warning:
Correlation-to-causation is the #1 Critical Reasoning trap on the GRE. The correct weakener points directly to an unobserved confounding factor that accounts for the observed correlation.
🎯 Key Rule:
When an argument infers causation from a statistical correlation, look for a third variable (confounder) that causes both.
A fifteen-year epidemiological study monitored 10,000 adults aged 50 to 70 and observed that participants who regularly consumed at least two ounces of dark chocolate daily exhibited a 40% lower incidence of coronary heart disease than those who consumed dark chocolate rarely or never. The investigators concluded that the potent polyphenol antioxidants concentrated in dark chocolate directly protect arterial endothelial function and reduce cardiovascular mortality in older adults.
Which of the following, if true, most seriously undermines the investigators' conclusion?
Show Official Answer & Step-by-Step Rationale
Correct Answer:Participants who regularly consumed dark chocolate were also significantly more likely to adhere to a Mediterranean diet and engage in daily aerobic exercise.
Step-by-Step Proof:
The researchers commit a classic Correlation vs. Causation error: they infer that dark chocolate directly causes cardiovascular protection simply because chocolate consumers had fewer cardiac events. Option B introduces two massive confounding variables: participants who ate dark chocolate also practiced daily aerobic exercise and ate a Mediterranean diet—both universally established to reduce heart disease. This alternative explanation destroys the claim that chocolate polyphenols were the direct causal agent.
Common ETS Trap Warning:
Option C explains why some chocolate has fewer polyphenols, but does not weaken the finding among participants who actually consumed them. Option A introduces theobromine without showing any negative cardiac effect.
🎯 Key Rule:
To weaken a causal claim derived from an observational study, introduce an alternate cause or confounding lifestyle factor (healthy user bias).
A municipal transit authority plans to replace its entire fleet of diesel buses with fully electric buses over the next three years. The city council asserts that because electric buses produce zero tailpipe emissions during operation, this transition will immediately reduce the total greenhouse gas emissions attributable to the city's public transit network.
Which of the following is an assumption upon which the city council's argument depends?
Show Official Answer & Step-by-Step Rationale
Correct Answer:The electrical grid powering the buses does not generate emissions equal to or greater than those produced by the diesel buses being replaced.
Step-by-Step Proof:
The argument concludes that total greenhouse gas emissions from the transit network will decrease because the buses have zero tailpipe emissions. However, electric vehicles require electricity from the local grid. If the power plants charging the buses emit more carbon than diesel combustion, total transit emissions would increase or remain unchanged. Therefore, the argument assumes the upstream electricity generation does not offset or exceed the tailpipe savings (Negation Test: If the grid produces equal or greater emissions, the conclusion fails).
Common ETS Trap Warning:
Option A focuses on financial costs, which are completely irrelevant to the conclusion about carbon emissions. Option D introduces an extraneous factor (adjacent municipalities), whereas the argument is scoped strictly to "the city's public transit network."
🎯 Key Rule:
Use the Negation Test for Assumption questions: negating the correct answer must completely invalidate the author's conclusion.
Which of the following, if true, most weakens the argument below?
Argument: After implementing a mandatory two‑day‑per‑week work‑from‑home policy, Company X observed a 15% increase in productivity over six months. Therefore, the policy caused the increase in productivity.
Show Official Answer & Step-by-Step Rationale
Correct Answer:A
Step-by-Step Proof:
Option A introduces an alternative explanation—the software upgrade—that could account for the productivity increase, thereby weakening the causal claim that the work‑from‑home policy alone caused the rise. The other options either support the argument (B, D, E) or are irrelevant to the causal link (C).
Common ETS Trap Warning:
Option C might seem relevant because it contrasts the company with a competitor, but the competitor’s lack of change does not address whether the policy caused the increase; it merely shows a correlation without ruling out other factors.
🎯 Key Rule:
To weaken a causal argument, look for evidence of an alternative cause or a confounding variable that could produce the observed effect.
A recent study found that employees who take short, frequent breaks report higher job satisfaction than those who work longer stretches without interruption. Therefore, companies should implement mandatory break policies to improve overall employee morale.
Show Official Answer & Step-by-Step Rationale
Correct Answer:Job satisfaction is directly caused by taking short, frequent breaks.
Step-by-Step Proof:
The argument assumes that the observed correlation (breaks ↔ higher satisfaction) implies causation—that breaks cause the satisfaction increase. Without this assumption, the recommendation to mandate breaks does not logically follow.
Common ETS Trap Warning:
Options A, C, D, and E introduce unrelated claims (quit rates, productivity, workflow, morale) that are not necessary for the argument’s conclusion. Only option B captures the hidden causal assumption.
🎯 Key Rule:
In assumption questions, identify the unstated premise that links the evidence to the conclusion; it often takes the form of a causal claim.
