PrepTest 133, Section 2, Question 14
Expert: What criteria distinguish addictive substances from nonaddictive(88 more words not shown)
Which one of the following(8 more words not shown)
- AIf a person(17 more words not shown)
- BFewer substances would(17 more words not shown)
- CA substance that(27 more words not shown)
- DA chemical substance(15 more words not shown)
- E"Addiction" is a(8 more words not shown)
Reading the argument
Someone manages to quit. Does that show the substance wasn't addictive?
Not necessarily. A person could get through a difficult withdrawal and still have been using an addictive substance. That is the problem with the first proposed rule: if even some habitual users can stop, it labels the substance nonaddictive. The expert says that rule would exclude substances medical experts regard as clear examples of addiction.
The expert then gives a requirement for a better account. To count as addictive, withdrawal from habitual use must cause most users extreme psychological and physiological difficulty. 'Most' means more than half. Notice that the difficulty must arise from stopping, not simply from using the substance.
What we’re looking for
We could debate that proposed requirement, but this question asks what follows from the expert's statements. My first takeaway is that the initial can-someone-quit test is inadequate. As we check the answers, we also need to respect the exact replacement requirement: more than half, withdrawal, and extreme difficulty. The expert gives a condition an addictive substance must meet, not a complete promise that meeting that condition alone settles the classification.
Working the answers
- A
One person's experience doesn't establish what happens to most habitual users. Suppose one person out of a hundred has extreme withdrawal difficulties. That alone doesn't establish the majority requirement the expert gives. A also treats the experience as enough to classify the substance, while the expert states a requirement for addiction rather than a complete test guaranteeing it.
- B
We don't know the current classification rules well enough to predict how many substances would change categories. The passage discusses a suggested criterion and a requirement for an adequate account. It doesn't say the suggested criterion is the definition currently in use. B needs that missing comparison between present classifications and the results of an adequate definition.
- CCorrect
Some people being able to stop easily doesn't rule out addiction. But if the substance is addictive under the expert's requirement, easy withdrawal can't be true for most habitual users. Most must instead experience extreme difficulty.
Imagine one hundred habitual users. If more than fifty have the extreme psychological and physiological difficulties required by the expert, more than fifty cannot also have little or no difficulty. A minority might stop easily; that doesn't conflict with the rule. C preserves both points: some easy quitters are possible, but a majority of easy quitters would prevent the substance from meeting the stated requirement.
- D
This person keeps using the substance throughout life. The expert's criterion concerns what happens during withdrawal. Someone might experience little difficulty while using a substance and serious difficulty after stopping it. D never supplies the relevant withdrawal information, and it again concerns only one user.
- E
Rejecting one proposed criterion doesn't establish that a precise definition is impossible. The expert is explaining what an adequate account must include. We haven't been told that no adequate account can be developed.
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