LSAT (Law School Admission Test)Logical ReasoningMedium
City Official: Our new public transportation system, which includes expanded bus routes and a new light rail line, has been a resounding success in reducing traffic congestion. Since its full implementation six months ago, peak hour commute times have decreased by an average of 10% across the city.
- AThe official does not provide data on the number of citizens who have switched from private vehicles to public transportation.
- BThe official overlooks the possibility that some residents may have moved out of the city, thus reducing overall traffic.
- CThe official assumes that no other factors could have contributed to the decrease in peak hour commute times.
- DThe official fails to consider whether the expansion of bus routes or the new light rail line was individually more effective.
Show answer & explanationAnswer & explanation
Correct answer: B. The official overlooks the possibility that some residents may have moved out of the city, thus reducing overall traffic.
The official attributes the decrease in commute times solely to the new transportation system. However, a reduction in the number of drivers (e.g., due to people moving away) could also significantly reduce congestion, independent of the new system's success. This represents an alternative cause for the observed effect.
Why the other options are wrong
- A. While helpful, this data is not strictly necessary for the claim about reduced congestion, and its absence isn't the primary logical flaw.
- C. This is a general statement of the causal flaw, but 'D' provides a specific, plausible alternative cause.
- D. This is a question about efficiency, not a fundamental flaw in the causal claim.
Alternative Cause (LSAT)
A flaw in causal reasoning where an argument attributes an effect to a specific cause, but fails to consider or rule out other plausible factors that could have produced the same effect.
- Often involves 'post hoc ergo propter hoc' fallacy.
- Requires considering multiple potential explanations.
- Weakens an argument by showing the stated cause might not be the *only* or *primary* cause.
Memory trick: Don't forget the 'other suspects' when identifying the cause.