Wednesday's questions and sample explanations - #10

10. When I was in high school, the teachers were always warning us against ever using drugs. Yet many of the students freely admitted in later years that they had used drugs regularly in high school. I can only draw the unfortunate conclusion from this that my teachers’ warnings were in vain.

Which one of the following claims, if true, would be most useful in refuting the argument of the passage above?

1. Many of the students who used drugs were aware of the dangers involved because of the teachers’ warnings.
2. Some students use drugs for legitimate reasons.
3. The school required the teachers to warn their students against drug use.
4. Some of the author’s fellow students were persuaded not to use drugs by their teachers’ warnings.
5. Drug use invariably results in bad study habits, poor class attendance and low grades.

(D) is correct. This is a classic example of a logical fallacy; it's called "inductive reasoning." The argument suggests that because some people did not take the teachers' advice, then that advice was given "in vain," i.e., that the advice did not do any good at all and might as well have not been given at all. In other words, because it didn't affect everyone, that means it didn't affect anyone. Obviously, that is not logical. If it is true that some of the students heeded the teacher's warnings, then those warnings were not given in vain.

(A) is incorrect even though it could weaken the argument. It suggests that the students learned something but did not act on it, but the purpose of the advice was that they act on it and refrain from using drugs. Therefore it is not the most useful fact with which to refute the argument.

(B) is incorrect because it's basically false (there are no "legitimate reasons" to use drugs), and more importantly because the argument is not concerned with why the students used drugs.

(C) is incorrect because the argument is also not concerned with why the teachers gave the students the advice.

(E) is incorrect even though it is probably true for the most part. The argument is not concerned with the abstract, hypothetical dangers of drug use.