Logical reasoning PrepTest 111 · Section 1 · Question 18

Incorrect. The argument notes that one possibility is to "do without" a resource so it doesn't assume that we can replace all of them.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
There's only so much of any nonrenewable resource, so we'll eventually have to switch to renewable resources or do without it, and thus we must change our resource use patterns.

Answer Anticipation:
The conclusion here makes a prediction about the future—that we'll eventually have to stop using nonrenewable resources and switch to renewable ones. Normally, predicting the future would be directly related to the flaw, as something could change in the future. However, in this case, the stimulus does establish that there's only so much metal ore available, and so there is a limited supply that is, theoretically, exhaustible.

Does this mean that we'll need to switch to renewable resources? Nope, for two reasons. First, the limited supply may be more than we'll ever need. Second, even if we run out of one nonrenewable resource, we may be able to start using another, and another when that runs out, and another when that runs out.

The argument is assuming that we'll go through the entire supply of any given nonrenewable resource and that there won't be a replacement for it, so let's find that answer.

Answer Explanation:
This answer eliminates one of the possibilities that would prevent the need for us to switch away from nonrenewable resources. If we can indefinitely replace one of them with another, then we wouldn't need to switch, killing the argument. This answer is thus correct.

Key Takeaway:
One of our anticipations here ended up being pretty close to the correct answer, but it's definitely an anticipation that would be hard to make on test day. When that happens to you, just stay flexible, know what's in scope, and use your negations to check to see if the answer completely destroys the argument.

Incorrect. The argument requires nonrenewable resources be exhaustible, not renewable ones. While renewable resources being exhaustible would create problems in the long—term, we could still need to switch to them if the nonrenewable ones run out sooner.

Incorrect. The consumption of these resources continuing to increase would help the argument as they'd run out faster, thus driving a shift to renewable resources. Since the negation of this answer helps the argument, it can't be necessary.

Incorrect. The argument recommends shifting away from nonrenewable resources, so it can't be assuming that they're necessary.