LSAT (Law School Admission Test)Logical ReasoningMedium
Biologist: The recent decline in the local frog population is primarily due to increased pesticide use in nearby agricultural areas. This conclusion is supported by observations that frog populations in areas with minimal pesticide exposure have remained stable or even increased.
- AThe biologist does not account for other potential environmental factors that could affect frog populations.
- BThe biologist fails to provide data on the specific types of pesticides used and their known effects on amphibians.
- CThe biologist fails to consider that the frog population decline might be a natural cyclical phenomenon.
- DThe biologist assumes that the amount of pesticide used in agricultural areas has increased recently.
Show answer & explanationAnswer & explanation
Correct answer: D. The biologist assumes that the amount of pesticide used in agricultural areas has increased recently.
The biologist concludes that increased pesticide use is the cause of the decline. However, the evidence only states that areas with minimal exposure have stable populations, not that pesticide use has actually increased in the areas where the decline occurred. This is a crucial unstated assumption.
Why the other options are wrong
- A. This is a valid criticism of the argument's completeness, but not its most central unstated assumption for the causal claim.
- B. While more specific data would strengthen the argument, the absence of it is not the most significant unstated assumption.
- C. While a natural cycle is an alternative cause, the argument's flaw is more fundamental regarding the premise about pesticide use.
Implicit Assumption (LSAT)
An unstated premise or belief that must be true for the argument's conclusion to logically follow from its stated premises. It bridges the gap between the premises and the conclusion.
- It is a necessary condition for the argument's validity.
- If the assumption is false, the conclusion cannot be true.
- Often found in causal arguments or those with conditional reasoning.
Memory trick: Look for the 'missing link' that connects the evidence to the conclusion.