Critical Thinking & Argument Evaluation Flashcards

A researcher argues: 'In countries where ice cream sales are highest, drowning rates are also highest. Therefore, ice cream consumption increases the risk of drowning.' Which of the following most precisely identifies the flaw in this argument?

Answer: The argument ignores a common cause — hot weather increases both ice cream sales and swimming activity — making the correlation spurious

While post hoc reasoning (option A) involves inferring causation from sequence, this argument doesn't rely on sequence — it uses co-occurrence. The precise flaw is a confounding variable (hot weather) that independently drives both variables, producing a spurious correlation. This is a common cause fallacy, not post hoc. Option C is incorrect because the flaw is structural, not about sample type. Option D is incorrect because no claim about sample size is made.

Consider the argument: 'Either we impose strict emissions regulations, or coastal cities will be underwater within 50 years. We cannot afford strict emissions regulations. Therefore, coastal cities will be underwater within 50 years.' Which response most effectively undermines this argument without denying either premise?

Answer: Arguing that the disjunction is not exhaustive — there may be other interventions, such as carbon capture or adaptation infrastructure, that prevent the predicted outcome

The argument is structured as a disjunctive syllogism (A or B; not A; therefore B), which is formally valid — but only if the disjunction is exhaustive. The most effective attack without denying either stated premise is to show the 'either/or' is a false dilemma: other pathways (carbon capture, sea walls, geoengineering) could prevent the outcome. Options A and D attack the premises directly. Option C critiques the framing of the conclusion but does not undermine the logical structure itself.

A politician states: 'My opponent voted against the education bill three times. Clearly, she does not care about children's futures.' A critic responds: 'That's an ad hominem attack.' Is the critic's classification correct?

Answer: No — the politician draws an inference about the opponent's values from her voting record, which is a legitimate form of evidence-based argument

An ad hominem fallacy attacks the person rather than the argument, typically by citing irrelevant personal characteristics. Here, the politician draws an inference about the opponent's values from her policy voting record — a form of evidence-based reasoning about character from relevant actions. While the inference may be contestable (she may have voted against the bill for procedural reasons), it is not an ad hominem. Ad hominem would be: 'She's a bad person, so her education policy is wrong.' The critic's label is misapplied.

The following analogy is used in an ethics debate: 'Allowing euthanasia is like allowing a doctor to push a patient off a cliff — both result in the patient's death.' Which evaluative statement about this analogy is most analytically rigorous?

Answer: The analogy is weak because it ignores the morally relevant distinction between an act performed at the patient's explicit request and an unconsented violent act

Analogies are evaluated by whether the compared cases share the features that are morally or logically relevant. The critical disanalogy here is consent and intent: euthanasia (in its legalised form) is typically requested by the patient to relieve suffering, whereas pushing someone off a cliff is non-consensual and violent. Option C critiques legal status rather than the moral logic. Option D presupposes a consequentialist framework without justification and ignores that consent is a morally relevant feature even within consequentialism.

A study finds that students who eat breakfast perform better on exams. A school board concludes: 'Mandating breakfast will improve exam performance.' Which of the following identifies the most significant inferential gap in this reasoning?

Answer: The correlation may reflect that students from higher socioeconomic households are more likely to eat breakfast and also have better academic support — mandating breakfast does not replicate the full causal package

The deepest inferential gap is between correlation and intervention. Even if breakfast correlates with performance, the causal mechanism may not be breakfast itself but rather the socioeconomic and home-environment factors that enable students to eat breakfast. Mandating breakfast replicates only one element of this complex. This is the 'intervention vs. correlation' problem — a common issue in policy reasoning. Options A and C raise validity concerns about the study but don't address the logical gap in applying the finding. Option D introduces a speculative new confound not grounded in the argument.

An author argues: 'No published study has conclusively proven that moderate alcohol consumption is harmful to the heart; therefore, it is safe to consume alcohol in moderation for cardiovascular health.' This argument most closely exemplifies which reasoning error?

Answer: Argument from ignorance (appeal to ignorance) — treating absence of proof of harm as proof of safety

The argument moves from 'no proof of harm exists' to 'it is safe' — a classic appeal to ignorance (argumentum ad ignorantiam). Absence of evidence is not evidence of absence, particularly in complex biomedical domains. The distinction from overgeneralisation (option D) is important: overgeneralisation concerns drawing broad conclusions from small samples, whereas this error concerns the logical status of null results. Option B is incorrect because no misrepresentation is alleged. Option C misidentifies the structure — the premises and conclusion are distinct.