- PowerScore Staff
- Posts: 8203
- Joined: Feb 02, 2011
Flaw in the Reasoning—#%. The correct answer choice is (B)
Based on the premise that roads with bicycle lanes have more car-and-bike collisions than roads without such lanes, the author of this stimulus concludes that the addition of bicycle lanes to existing roads would not be likely to make cyclists safer:
- Premise: Roads with bike lanes have more car/bike accidents.
Conclusion: Adding such lanes to existing roads would not likely increase cyclists’ safety.
The question asks for the flaw in the author’s reasoning. As discussed, the author’s conclusion is based on limited information.
Answer choice (A): The author need not have addressed the possibility that the seriousness of injuries sustained in car-and-bicycle collisions might be about the same regardless of the presence of bike lanes, because the author’s conclusion does not rely on this comparison. While this choice might strengthen the author’s argument, its absence is not a flaw in the author’s reasoning, so this answer can be ruled out.
Answer choice (B): This is the correct answer choice. As discussed above, the author fails to consider that roads with bike lanes are likely to attract more cyclists. If that is the cause of the greater number of bike-and-car collisions, rather than the mere presence of bike lanes, then this would significantly weaken the author’s conclusion.
- Cause Effect
Author’s implication: Lower level of safety Greater number of car-bike collisions
This choice: More cyclists Greater number of car-bike collisions
Answer choice (C): The author does not assert, or imply, that every safety enhancement will benefit both cyclists and motorists, and the author’s conclusion is only about the safety of cyclists, so this choice can be quickly ruled out of contention.
Answer choice (D): The author of the stimulus does not assert that only some bike-lane-equipped roads are safe, but rather that such roads (in general) have more bike-and-car collisions than roads without such lanes. Since this choice does not actually reference a premise used by the author, this cannot be the correct answer choice.
Answer choice (E): This choice was appealing for many test takers, because the argument’s flaw can be expressed as statistical in nature. The problem, however, is that the author does not conclude that anything is proven. Rather, the author takes limited statistical evidence (more accidents on roads with bike lanes) which seems to lack support for the increased-safety-proposition, and concludes that adding bike lanes is unlikely to increase safety levels. This is not the same as proving the opposite conclusion, and this choice fails to specify the real flaw in the author’s argument, so this cleverly worded choice should be ruled out of contention.