PrepTest 133, Section 2, Question 9
Letter to the editor: I have never seen(78 more words not shown)
The reasoning in the letter(7 more words not shown)
- Abases its conclusion(10 more words not shown)
- Bfails to consider(14 more words not shown)
- Cfails to consider(9 more words not shown)
- Dfails to consider(13 more words not shown)
- Edoes not present(8 more words not shown)
Reading the argument
A rising fatality rate doesn't automatically overtake a higher one.
Suppose the areas with lower speed limits go from one vehicle-related death per 100,000 people to two. If the rate in the other areas is ten, the first rate is still lower. It rose, but two hasn't become bigger than ten.
Think about getting a raise. Earning more than last year doesn't mean you're about to catch a billionaire. To make that comparison, we need to know where both sides stand, not just that one side has gone up.
The letter writer has the same problem. We hear that fatality rates are rising in areas with lower speed limits, then we're told those areas won't have lower rates for long. What's happening in the other areas? The writer hasn't filled in that half of the comparison.
And why would raising the speed limit fix the increase? Perhaps distracted driving is making those roads more dangerous. A higher limit wouldn't remove that distraction and might make crashes worse. The rising rate doesn't by itself identify the speed limit as the cause or show that increasing it would help.
What we’re looking for
We're asked for a flaw. I'd focus on the incomplete comparison: a change in the lower-speed areas doesn't tell us their rate will exceed the rate elsewhere. Keep that objection in mind while checking exactly what the choices say.
Working the answers
- A
It's possible to use an article's own data to challenge its interpretation. That wouldn't automatically be faulty reasoning. Here, the writer reports the article's comparison, but doesn't even specify where the claim about rising rates came from. Either way, the problem is what the evidence shows, not whether a critic may use the same source's findings.
- B
We're already comparing fatality rates, not merely counting crashes as though every crash were equally serious. If the argument had only compared accident numbers, we might object that a minor collision and a fatal crash shouldn't count the same. But B doesn't tell us how the fatality rates in the two areas compare or how either is changing. It misses the gap in the writer's comparison.
- C
Some people preferring to drive slowly doesn't resolve the evidence about deaths. The recommendation is supposedly supported by fatality rates, so we need to evaluate what those rates establish. Drivers' preferences don't supply the missing comparison.
- DCorrect
The other areas' fatality rates could be rising too. We had asked what's happening on that side of the comparison; D supplies a possibility the writer overlooked.
Suppose the lower-speed areas go from one to two deaths per 100,000 people, while the other areas go from two to three. The lower-speed areas have gotten worse, but their rate remains lower. Their increase doesn't establish that they will catch up, because the other rate needn't stand still. That undermines the writer's claim that the original comparison will soon stop being true.
- E
The writer does present evidence: fatality rates are rising in areas with lower speed limits. That claim is offered as a reason to reject the article's position. We can reject the inference without pretending no support was attempted. Insufficient evidence and no evidence are different criticisms.
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