Examkin

Question

Difficulty: HardWeaken

Transit Administrator: To reduce commuter exposure to airborne fine particulate matter, our municipal agency replaced its diesel bus fleet with zero-emission electric buses along the central downtown corridor. However, monitoring devices installed inside passenger cabins six months after the transition recorded an 18 percent increase in average fine particulate concentrations during peak commute hours. Therefore, the ventilation and filtration mechanisms in the new electric buses generate more interior airborne particulate matter than those in the retired diesel buses.

Statement: If true, the discovery that major roadway reconstruction began along the central downtown corridor during the six-month period, generating elevated street-level dust that entered passenger cabins during frequent passenger boarding stops, weakens the transit administrator's argument.

Answer: Answer

Answer

True
The claim is true because introducing an external source of particulate matter (roadway reconstruction dust entering during passenger stops) provides a compelling alternative cause for the 18 percent increase, thereby invalidating the author's assumption that the bus's internal ventilation mechanisms must be the cause.

Step-by-Step Solution

1
Analyze the stimulus to isolate the premises and the conclusion.
Premises: Diesel buses were replaced with electric buses; interior cabin sensors showed an 18 percent increase in fine particulate matter six months later during peak hours. Conclusion: The ventilation and filtration systems in the electric buses generate more particulate matter than those in diesel buses.
Deconstructing the argument establishes the precise causal relationship asserted by the author.
2
Identify the unstated assumption and the vulnerability in the causal inference.
The author assumes that no external factors or alternative sources account for the rise in cabin particulates, attributing the entire increase strictly to internal generation by the bus ventilation mechanisms.
Causal arguments on the LSAT are vulnerable to alternative explanations for the observed effect.
3
Assess the impact of the supplementary information in the statement.
The discovery of concurrent roadway reconstruction reveals an external source of heavy particulate matter that entered the bus cabins through open doors during passenger stops.
An alternative causal mechanism accounts for the data without requiring the electric bus systems to generate particulates.
4
Determine the validity of the claim that this fact weakens the argument.
Because providing an alternative explanation directly diminishes the probability that the author's causal conclusion is correct, the new information genuinely weakens the argument. Thus, the statement is True.
Confirming the weakening effect directly verifies the truth value of the evaluation statement.

Key Concept

Weakening a causal conclusion by introducing an alternative explanation for an observed correlation
Estimated Time:1m 30s
Rate this question

Topics

Weaken

More questions from this topic