Self-study
Conclusion 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. ██ ███ ███████ ████ ██ ███ ████████ ██ █████ █████ ███████████████ ███ ███ █████████ ██ ████ █████████ ███ █████ ████████ ███ ████ ██ ████ ████████ ██████████ ███ ████ ██ ██████ ██ █████ ████ ███ ████████ ████ ███ █████ █████ ██ ██████████ █████████ ████████ ███████████████ ███ █████ ████ █████ ██████████ █████████
Summarize Argument: Phenomenon-Hypothesis
The author argues that triple-trailers, which are not currently allowed on national highways, are not more dangerous than other commercial vehicles. This follows from a key sub-conclusion: the hypothesis that triple-trailers are actually safer than other commercial vehicles. This is based on data from the West, where triple-trailers are allowed on highways. There, the fatality rate for triple-trailers is lower than the national rates for other commercial vehicles.
Notable Assumptions
The author assumes that the triple-trailer fatality rate in the West would be equivalent to the rate across the country as a whole. That’s the only reason to compare triple-trailer rates from the West to other vehicles’ national rates.
The author also assumes that vehicles’ safety is represented by those vehicles’ traffic fatality rates alone, and not, for example, injury rates.
3.
Which one of the following, ██ █████ ████ █████████████ ███████ ███ █████████
a
It takes two ███████ ████████████ ██ ████ ██ ████ ██████ ██ █ ██████ ██████████████ ████
This does not weaken the argument. The amount of cargo that different types of vehicles can haul has no bearing on how we assess the safety of those vehicles. This claim is just irrelevant to the argument.
b
Highways in the ████████ █████████ ████ ███ ████ ████ ███████ ████████ ███ ████████████ ███ ███ █████ ████ ████████ ██ ███ ████████ ██████ ██ █ ██████
This weakens the argument by undermining the author’s comparison of triple-trailer fatality rates from the West against other vehicles’ national rates. This claim undermines the conclusion that triple-trailers are overall safer—instead, they’re just being driven in safer areas.
c
Opponents of the ███████████████ ████ ████ ███████ ███ ███████ ██████████████ █████ ███ ███ ██████ ██ ███ ████████ █████████
This does not weaken the argument. Whatever else the opponents have ever opposed is totally irrelevant to how safe triple-trailers are. Even if we knew how safe twin-trailers are, which we don’t, this wouldn’t do anything to the argument.
d
In areas where ███ ███████████████ ███ ██████████ ███████ ████ █ ███████ ███████ ██ ███████ █████
This does not weaken the argument. If anything, this could strengthen by providing a mechanism for triple-trailers’ safety. We don’t know whether other commercial vehicle drivers also need special licenses, though, so it’s hard to compare. Either way, no weakening here!
e
For triple-trailers the ████ ██ ████ ████████ ██████████ ███ ████ ██ ██████ ███ ██████ ████ ████ ████ ██ ███ ███ ████████ ██████
This does not weaken the argument. How triple-trailer fatality rates have changed over the last few years tells us nothing without more information. How big was the change? Do we know what caused it? We don’t know. As it is, this is just irrelevant to the argument.