LSAT (Law School Admission Test)Logical ReasoningHard
A medical researcher states: 'Despite the common belief that regular consumption of vitamin C supplements prevents the common cold, studies consistently show no significant difference in cold incidence or duration between supplement users and non-users. Therefore, the widespread use of vitamin C supplements for cold prevention is a waste of money.' Which of the following is a flaw in the researcher's reasoning?
- AIt assumes that preventing the common cold is the only potential benefit of vitamin C supplements.
- BIt generalizes from a lack of evidence of a difference to evidence of a lack of a difference.
- CIt relies on studies that may not accurately reflect real-world vitamin C consumption patterns.
- DIt fails to consider that some individuals might experience a benefit from vitamin C supplements.
Show answer & explanationAnswer & explanation
Correct answer: B. It generalizes from a lack of evidence of a difference to evidence of a lack of a difference.
The researcher observes 'no significant difference' (lack of evidence for a difference) and concludes that there *is no difference* (evidence of a lack of difference), which is a common logical flaw. The studies simply failed to *detect* a difference, not necessarily that one doesn't exist.
Why the other options are wrong
- A. The argument specifically addresses cold prevention. Assuming this is the *only* benefit is not a flaw in the logic *regarding cold prevention*, though it might limit the scope.
- C. This questions the studies' methodology, but the flaw in reasoning concerns the *interpretation* of the studies' findings, not the findings themselves.
- D. While possible, the argument is about *widespread use* and *significant difference*, not individual, anecdotal benefits. This doesn't pinpoint a flaw in the logical jump.
Flaw in Reasoning (Fallacy)
A flaw in reasoning, or fallacy, is an error in an argument's logical structure that makes the conclusion not necessarily follow from its premises, even if the premises themselves are true.
- Undermines the validity of the argument.
- Can be formal (structural) or informal (content-based).
- Common types include causal, sampling, and generalization errors.
Memory trick: Don't trip on the logic, or your argument might just break.