Logical Reasoning

PT106 · S2 · Q3 Opponents of allowing triple-trailer

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Opponents of allowing triple-trailer trucks to use the national highway system are wrong in claiming that these trucks are more dangerous than other commercial vehicles.

Conclusion (clearly)

Triple-trailers are safer than other commercial vehicles.

Evidence

In areas where triple-trailers are permitted on highways (the western part of the country), the rate of fatalities per mile is lower than the national rate of fatalities per mile for all other commercial vehicles.

Evaluate

Since the author is interpreting the causal significance of a statistic (a Curious Comparison), we can use our Curious Fact / Explanation mindset.

Curious Fact .... why do triple-trailers have fewer fatalities per mile than the average rate of other commercial vehicles?

Author's Explanation ... triple-trailers are safer than other commercial vehicles.

We can think about weakening this argument by providing an alternate explanation for why the triple-trailers have a lower fatality rate (maybe there are fewer passengers riding in them, so fewer fatalities per accident ... maybe the drivers are just better, safer drivers, etc.)

Or we can weaken by undermining the plausibility that triple-trailers are safer (they have more blind spots ... their braking distance is much greater ... they're more prone to computer braking malfunctions, etc.)

Goal

The more common tendency for Weaken is to provide an alternate explanation for the curious fact, so primarily we'll look for some different way to explain why triple-trailers are getting fewer fatalities per mile.

But we'd also consider any answer that makes it seem like triple-trailers are not safer than other commercial vehicles.

Which one of the following, if true, most substantially weakens the argument?

It takes two smaller semitrailers
No Impact
This answer only talks about freight-load capacity, but it doesn't tell us anything that directly relates to safety. We might think, "heavier loads would make the triple-trailers more dangerous in a collision". True, but the author is just going to say, "Yes, all things being equal, heavier vehicles can cause more fatalities. But check the stats --- the triple-trailers have fewer fatalities per mile than other commercial vehicles."
1% picked this
Correct
Highways in the sparsely populated
Why this is right
Here is our alternate explanation for the curious fact. This allows us to say, "triple-trailers don't have fewer fatalities per mile because they're less dangerous; it's just because they aren't on the road around other vehicles. The roads they're driving are much less heavily traveled and thus far safer." The comparison looks unfair now. You can't say Kelly is faster than Selena by citing their 100 m dash times, if it turns out that Kelly's time involved having a strong wind at her back and Selena's didn't. The triple-trailers are only found in the open, sparse western part of the country, where you might not see another vehicle for many miles, whereas the average fatality/mile rate for other commercial vehicles is being tabulated as a "national rate", so it includes all the fatalities that occur on heavily congested and thus far more dangerous roads.
Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.
84% picked this
Opponents of the triple-trailers also
No Impact
If anything, this feels like a strengthener, since it's feeling like, "People who think triple-trailers are scary thought twin-trailers were, and now the latter is common. So they're probably wrong about triple-trailers too." So it's certainly not enticing on a Weaken question. But it also doesn't technically strengthen the claim that X is true to say "people who oppose X have been wrong before".
1% picked this
In areas where the triple-trailers
Unclear Impact
This is somewhat tempting, because we might consider an alternate explanation such as, "Triple trailers don't have a lower fatality rate because they're less dangerous than other vehicles; it's because they are only driven by the best-of-the-best drivers (i.e. safer drivers are the real reason)." The problem is this answer just says that they need a special license to operate them. Does needing a special license show us that triple-trailer drivers are better/safer drivers than double-trailer or single-trailer drivers? No, all truck drivers need special licenses. A regular old driver's license does not suffice to drive a commercial vehicle (you need a special Class C license). So this answer doesn't establish a clear distinction between triple-trailer drivers and drivers of other commercial vehicles.
4% picked this
For triple-trailers the rate of
No Impact
The fact that the fatality rate for triple-trailers appears to be higher now than before, suggests that maybe they're getting more dangerous? However, no matter how dangerous they've become, as measured by fatalities per mile, we know that the national rate for other commercial vehicles is even higher. Since this argument is about which is safer, not whether triple-trailers are safe, this answer has no impact.
11% picked this

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