LSAT (Law School Admission Test)Logical ReasoningMedium
A biologist states: 'The recent decline in the local frog population is due to increased pesticide use in agricultural areas bordering their habitats. Studies show a direct correlation between pesticide runoff and frog mortality rates.'\n\nWhich of the following, if true, would most weaken the biologist's conclusion?
- AOther local amphibian populations, not exposed to these pesticides, have also experienced similar declines.
- BThe decline in the frog population began several years before the significant increase in pesticide use.
- CSome pesticides used in the area are specifically designed to be less harmful to amphibians.
- DThe species of frogs in question are known to be particularly sensitive to environmental changes.
Show answer & explanationAnswer & explanation
Correct answer: B. The decline in the frog population began several years before the significant increase in pesticide use.
The biologist argues that increased pesticide use caused the decline. Option B suggests that the effect (decline) occurred before the proposed cause (increased pesticide use), thus challenging the causal link. This is a classic case of 'Reverse Causation' or 'Temporal Discrepancy' flaw.
Why the other options are wrong
- A. This introduces an alternative cause, but it's less direct than B in disproving the specific timing of the biologist's claim.
- C. While some pesticides might be less harmful, this doesn't mean *all* or *the specific ones in question* are harmless, and it doesn't directly contradict the correlation or timing.
- D. This supports the idea that frogs are vulnerable, but doesn't challenge the specific cause (pesticides) proposed.
Temporal Discrepancy Flaw
Occurs when an argument uses events that happened at different times to establish a causal relationship, but the timing of the events makes the proposed causation impossible or highly improbable.
- Challenges the 'before and after' requirement for causation.
- Often involves the effect preceding the supposed cause.
- A specific type of 'correlation is not causation' flaw.
Memory trick: Time travel can't be a cause; check the clock.