LSAT 92 - Section 1 - Question 02

This is an NA question.

The question tests reasoning about sets and intersections between sets.

The argument tells us that while the audience for part one of a documentary TV series was small, the audience for part two was not that much smaller. Thus, most of the viewers who watched the program the first night (the “small” set) liked it enough to tune in again the next night.

Wait, what? How do we know this? All we know is that on the first night, a small set of people watched part one and that on the second night, a smaller (but not by much) set of people watched part two. That doesn’t imply there has to be significant overlap in the two sets.

So that’s a huge gap we need to fill. How we fill the gap depends on what the answers give us because filling the gap in a necessary assumption manner can generate a very weak statement. That’s what Correct Answer Choice (A) does. It says most viewers who tuned in to the program on the second night had also watched the first night. Because the second night is the smaller set, at least half of that set must overlap with the first (larger) night set. Otherwise, there’s no way that more than half of the first (larger) night set can find itself within the second night set. That’s stating the issue in abstract terms, in terms of sets and intersections. The advantage of abstracting is to help you recognize patterns. Other questions will (and have) manifest(ed) the same issue.

In concrete terms, imagine you have 100 people in the first (larger) night set and 80 people in the second (smaller) night set. (A) claims that at least 41 from the second night set must have come from the first night set. That must be true. Imagine if it were false. If only 40 (of the 80) came from the first night set, then that means 60 (of the 100) from the first night set did not watch on the second night. That contradicts the conclusion.

Note that just because (A) is true, that doesn’t guarantee that the conclusion is true. It’s still possible for the conclusion to be false. But that doesn’t matter since this is an NA question and not an SA question. We need (A) as an NA because its truth is what makes it possible for (as opposed to guarantees) the conclusion to follow.

Answer Choice (B) says most of the viewers who tuned in to the program the second night liked it. This is not necessary. We don't care about the second-night viewers' enjoyment of the program. Even if every single viewer who tuned in on the second night hated it, the argument can still follow. It’s still possible that more than half of the first-night viewers tuned in on the second night. (B) would simply mean that they probably regretted that decision.

Answer Choice (C) says most of the viewers who watched the program both nights enjoyed the first night more than the second night. This is not necessary. We do not need to compare how much the viewers enjoyed the program on the first versus the second nights. Whether they liked the first night more than the second has no bearing on the argument.

Answer Choice (D) says many of the viewers who tuned in to the program the first night but not the second night were unable to watch the program on the second night. This is not necessary. The argument would be just fine even if all of the first-night-only viewers were able to (but chose not to) watch on the second night. (D) is about why some people are first-night-only viewers. (D) says it’s because they were unable to watch the second night (maybe scheduling conflict, or their power went out, or whatever). But the argument doesn’t care.

Answer Choice (E) says many of the viewers who watched the program on the first night were people who generally like to watch TV documentaries. This is not necessary. We already know that the first-night people watched this documentary regardless of whether they generally like documentaries.