LSAT (Law School Admission Test)Logical ReasoningMedium
Biologist: The recent increase in the population of a certain invasive beetle species is a direct result of climate change. Warmer average temperatures have allowed the beetles to complete more reproductive cycles each year, leading to a rapid population explosion. Which of the following, if true, would most seriously weaken the biologist's conclusion?
- AEffective natural predators of the beetle species have been introduced to the region in recent years.
- BThe increase in the beetle population began several years before a measurable rise in average temperatures.
- CThe invasive beetle species is native to a region that has historically experienced warmer temperatures.
- DOther insect species in the same region have not shown similar population increases.
Show answer & explanationAnswer & explanation
Correct answer: B. The increase in the beetle population began several years before a measurable rise in average temperatures.
The biologist argues that increased temperature (climate change) caused the beetle population increase. Option C directly undermines this by stating the effect (beetle increase) occurred *before* the proposed cause (temperature rise). This suggests that climate change cannot be the direct cause, thus weakening the conclusion.
Why the other options are wrong
- A. This suggests a factor that might *reduce* the beetle population, but it doesn't weaken the claim about what *caused* the initial increase. If anything, it makes the observed increase despite predators even more puzzling.
- C. This might explain why the species tolerates warmer temperatures, but it doesn't weaken the claim that *increasing* temperatures in the *new* region are causing a population boom.
- D. This suggests the beetle's case is unique, but doesn't weaken the specific causal link proposed for the beetle itself.
Temporal Discrepancy (Causal Flaw)
A flaw in causal reasoning where the proposed cause occurs after the observed effect, or there is a significant mismatch in their timing, making the causal link implausible.
- Cause must precede effect
- Challenges chronological order
- Undermines direct causality
Memory trick: The effect can't start before the cause even begins!