Self-paced
Drivers in the country of Holston want highway tolls eliminated. ███ ████ ██ ███████████ ███ ████████ ██ ████ ████████ ███ ██ ███████ ████ ███ ███████ ██████ ███████ ████ ████████ ███ █████████ █████ ██ ███████ ████ ██ ███ █████ ███ ███████████ ████ ███ ██████ ████ ██ ███████████ ███ ████████ ████ ████ ██ ██ ████ ███ ██ ██ ████████ ██ ███████ ██████
Objective: Identify a Necessary Assumption
The argument concludes that if Holston eliminates its highway tolls, then the entire cost of highway maintenance must be paid for through increased general taxes. In support, the argument explains that the entire maintenance cost is currently paid for by highway toll revenue. And it's essential that Holston maintain its highways.
Looking closely, we can see a gap between the premises and conclusion: why are general taxes the only alternative way to pay for highway maintenance? The argument must assume that there are no other revenue sources that could be used—such as property tax, car licensing fees, or so on.
17.
Which one of the following ██ ██ ██████████ ████ ██ ███ █████████
a
Work on highway ███████████ ███ ██ ██████████ ████ ██ ███ █████ ██████ ██ ███ ███ ██ ███ ███████ ████ ██████████
We already know that highway maintenance needs to be paid for. The exact timing of collecting money versus authorizing work isn't necessary to assume. If we negated (A), and said the work could be authorized even before collecting the money, the argument would still make sense.
b
The amount of █████ █████ ██ ███████████ ███ █████ ██████████ ████ ████ ██████████ █████ ███ ██ █████████ ██ ███ ████ ██ ███ █████ ████ ██ ███████████ ███ █████████
(B) rejects a specific alternative revenue source that might pay for some of the maintenance cost. This is part of the broader necessary assumption that general taxes are the only option to pay for highway maintenance, making (B) also necessary.
We can also see this through negation. If (B) were untrue, and the money saved on toll collection could actually pay for some highway maintenance, then the argument would fall apart. It just wouldn't make sense to say that general taxes must cover the entire cost.
c
If the highway █████ ███ ██████████ ███ ███ ███████ █████ ███ █████████ ██ ███ ███ ███████████ ███ █████████ █████ ████ ██ ████ ████████ ██ ██████████ ████████████
The argument doesn't address preventive maintenance one way or another. We don't know if switching from tolls to general taxes will lead to any change in the maintenance budget, let alone a change in the type of maintenance performed. (C) doesn't need to be true for the argument to stand.
d
The total cost ██ ███████████ ███ ████████ ████ ██ ████ ██ ███ ███████ █████ ██████ ████ ███ ███████ █████ ███ ███ ███ ████████████
We can see that (D) is not necessary through negation. If the total cost of maintenance remained the same—or even decreased—after eliminating tolls, the argument wouldn't fall apart. Whatever the total cost, some other revenue stream still has to pay for it if tolls are eliminated.
e
If the highway █████ ███ ███ ███████████ █████ ████ ██ ██ ████ ██ ████████ ███ ███████ ██████
(E) is effectively an inversion of part of the argument's conclusion. The conclusion says in part that if tolls are eliminated, then general taxes must increase. (E) confuses the sufficient and necessary conditions of this claim, which is not necessary.
If we negate (E), and say that general taxes will increase anyway, that doesn't break the argument. Whether or not general taxes would increase independently, it could still be true that eliminating highway tolls will cause them to increase.