Logical Reasoning: Strengthen and Support Questions Flashcards

A scientist argues that a newly discovered bacterium causes a specific skin disease because patients with the disease all test positive for the bacterium. Which of the following, if true, most strengthens this argument?

Answer: Healthy individuals without the skin disease consistently test negative for the bacterium.

Establishing that healthy people test negative (completing the necessary correlation pattern) significantly strengthens the causal claim by showing the bacterium and disease co-occur and co-absent.

A city argues that its new after-school tutoring program increased graduation rates, pointing to a rise from 78% to 85% graduation rate after implementation. Which of the following most strengthens this argument?

Answer: Neighboring cities without similar programs showed no comparable improvement in graduation rates during the same period.

A comparison group showing no improvement rules out external factors (economic conditions, demographic shifts) as alternative explanations, strengthening the inference that the program caused the improvement.

A nutritionist argues that a specific probiotic supplement improves digestive health in adults with irritable bowel syndrome (IBS). Which of the following most strengthens this argument?

Answer: In a randomized controlled trial, IBS patients taking the probiotic reported significantly fewer symptoms than those receiving a placebo.

A randomized controlled trial with a placebo group is the gold standard for establishing causation, directly supporting the effectiveness claim with rigorous evidence.

An archaeologist argues that a coastal settlement was abandoned due to rising sea levels, rather than warfare or disease. Which of the following most strengthens this argument?

Answer: Sediment core samples from the region show evidence of rapid sea-level rise occurring precisely at the time of the abandonment, with no evidence of mass casualties or violent destruction.

Geological evidence directly confirming sea-level rise at the abandonment date, combined with absence of warfare/disease evidence, supports the specific causal claim over the alternatives.

A health researcher argues that moderate coffee consumption (2-3 cups daily) reduces the risk of type 2 diabetes. Which of the following most strengthens this argument?

Answer: A mechanism has been identified: compounds in coffee improve insulin sensitivity by activating specific cellular receptors.

Identifying a specific biological mechanism (how coffee affects insulin receptors) provides a plausible causal pathway, substantially strengthening the correlation between coffee consumption and reduced diabetes risk.

A geologist argues that a particular rock formation was created by a massive ancient volcanic eruption rather than gradual sedimentary processes. Which of the following most strengthens this argument?

Answer: The rock formation contains minerals that can only form under the extreme heat and pressure conditions produced by volcanic eruptions, not sedimentary processes.

Minerals that can only form under volcanic conditions provide direct chemical evidence for volcanic origin, ruling out sedimentary formation processes.

A social scientist argues that income inequality causes social unrest, citing a correlation between higher inequality (measured by Gini coefficient) and greater political instability across countries. Which of the following most strengthens this argument?

Answer: Historical analysis shows that periods of increasing inequality in stable societies are reliably followed by increases in social unrest, before external factors changed.

Temporal sequencing (inequality increases followed by unrest increases) within societies provides stronger causal evidence than cross-sectional correlation, and the phrase 'before external factors changed' helps rule out reverse causation.

A pharmaceutical researcher argues that a new antibiotic is effective against a drug-resistant bacterial strain. Which of the following most strengthens this argument?

Answer: Laboratory tests show the antibiotic kills the resistant strain at low concentrations, and animal trials show complete infection clearance with no evidence of new resistance developing.

Laboratory efficacy data plus animal trial success and absence of new resistance development provides multi-layered evidence directly supporting both effectiveness and durability of the treatment.

An economist argues that trade liberalization increases economic growth in developing countries. Which of the following most strengthens this argument?

Answer: Countries that liberalized trade showed accelerated GDP growth in the years following liberalization, while those that did not liberalize showed no comparable growth acceleration despite similar starting conditions.

A quasi-experimental comparison showing that liberalizing countries grew faster than non-liberalizing countries with similar starting conditions provides strong causal evidence for the economic growth claim.

A psychologist argues that cognitive behavioral therapy (CBT) is more effective than medication alone for treating panic disorder. Which of the following most strengthens this argument?

Answer: In a study where panic disorder patients were randomly assigned to CBT, medication, or combined treatment, CBT patients showed lower relapse rates at 12-month follow-up than medication-only patients.

A randomized study with long-term follow-up showing lower relapse rates directly addresses both the comparative efficacy claim and demonstrates durable advantage for CBT over medication alone.

A wildlife biologist argues that sea otter populations control sea urchin numbers, which in turn protects kelp forests. Which of the following most strengthens this argument?

Answer: In areas where sea otters were hunted to near-extinction, sea urchin populations exploded and kelp forests disappeared, and when otters were reintroduced, urchin numbers declined and kelp forests recovered.

The natural experiment of otter removal causing kelp collapse and otter reintroduction causing kelp recovery provides strong before-after-during evidence for the trophic cascade the biologist describes.

An environmental scientist argues that reducing vehicle emissions in urban areas will improve residents' respiratory health. Which of the following most strengthens this argument?

Answer: Cities that implemented strict emission reduction zones showed measurable decreases in asthma hospitalizations and respiratory illness rates in the years following implementation.

Empirical data from cities that implemented emission reductions showing direct decreases in respiratory health outcomes provides real-world validation of the proposed causal pathway.

A linguist argues that early childhood bilingualism enhances executive function (cognitive control) compared to monolingual upbringing. Which of the following most strengthens this argument?

Answer: In laboratory tasks measuring cognitive control, bilingual children who have used both languages since birth perform significantly better than monolingual peers matched for age, socioeconomic status, and IQ.

Controlled laboratory comparison with socioeconomic status and IQ matching eliminates key confounders, directly measuring the specific cognitive advantage claimed.

A public health researcher argues that restricting fast food advertising during children's television programming will reduce childhood obesity rates. Which of the following most strengthens this argument?

Answer: Countries that implemented such advertising restrictions showed significantly lower rates of childhood obesity increase compared to countries that did not implement restrictions during the same period.

Cross-national comparison showing lower obesity growth in countries with advertising restrictions versus comparable countries without restrictions provides quasi-experimental evidence supporting the causal claim.

A historian argues that the development of the printing press was the primary cause of the Protestant Reformation, because it enabled mass distribution of reformist ideas. Which of the following most strengthens this argument?

Answer: Reformist ideas very similar to those of Luther and Calvin existed for centuries before the Reformation but failed to spread widely, while the same arguments printed and distributed after 1450 reached mass audiences within weeks.

The historical comparison shows that the ideas themselves were not new—distribution technology was the differentiating factor, directly supporting the printing press as the primary enabling cause.

A criminal justice researcher argues that community-based rehabilitation programs reduce recidivism more effectively than incarceration. Which of the following most strengthens this argument?

Answer: When similar offenders were randomly assigned to community programs versus incarceration, those in community programs had significantly lower re-arrest rates over a 5-year follow-up period.

Random assignment eliminates selection bias (the concern that lower-risk offenders are systematically placed in community programs), providing strong causal evidence that community programs reduce recidivism.

An agricultural scientist argues that crop rotation improves soil health and increases yields over time compared to monoculture farming. Which of the following most strengthens this argument?

Answer: Long-term experimental plots randomly assigned to crop rotation versus continuous monoculture show progressively widening yield gaps over 10+ years, with rotation plots maintaining consistent yields while monoculture plots decline.

Long-term randomized experimental data showing diverging yield trajectories provides the strongest evidence that rotation specifically causes sustained soil health and yield advantages.

A tech analyst argues that user interface simplicity increases app adoption rates, citing successful minimalist apps. Which of the following most strengthens this argument?

Answer: A/B testing of identical app features with simple versus complex interfaces showed significantly higher adoption and retention rates for the simple interface across multiple demographic groups.

Controlled A/B testing isolates interface complexity as the variable and demonstrates its causal effect on adoption across diverse groups, providing the strongest evidence for the claim.

A climate scientist argues that ocean acidification caused by CO2 absorption is harming coral reef ecosystems. Which of the following most strengthens this argument?

Answer: Controlled aquarium experiments exposing coral to seawater with elevated CO2 concentrations show measurably reduced calcification rates and skeletal weakening at concentrations already observed in some ocean regions.

Controlled experiments demonstrating the specific biological mechanism at CO2 concentrations already present in some ocean regions provides strong causal evidence linking acidification to coral harm.

A sociologist argues that strong social networks improve mental health outcomes for elderly individuals living alone. Which of the following most strengthens this argument?

Answer: Elderly individuals who received systematic social visitation programs showed significantly lower rates of depression and cognitive decline at 2-year follow-up compared to matched controls who did not receive the programs.

An intervention study with matched controls and long-term follow-up directly tests whether providing social connections (not just having them) causally improves mental health outcomes.