LSAT 155 - Section 1 - Question 17

This is a Flaw/Descriptive Weakening question.

The stimulus begins with a premise about a “new experimental curriculum” that a plumbing school has been using “for several years.” Then it says that a survey last year found that only 33% of the school’s graduates passed the certification exam, and that 33% is not good because the national average is “well above” that. Those are the premises. From those premises, the conclusion claims that the new curriculum has “lowered the quality of plumbing instruction.”

What?

Where did we encounter a decrease in the quality of plumbing instruction? We only have one static data point. We need at least two data points to show change. What was the pass rate last year and the year before? Was it higher? If it was higher than 33%, then maybe instruction has declined. But if it was lower, then maybe instruction has improved. That’s a major issue in this argument.

The only evidence we have from the argument, the results of the exam, shows that there’s something subpar about the plumbing school. It likely has something to do with the quality of the instruction. But there could also be other causal forces at work. Maybe its students. Maybe the school was severely damaged last year in a catastrophic fire.

Okay, so if you spot the weakness, you’re almost there. You still have to jump over the hurdle of the abstractly worded answers.

And it starts with the worst offender, Answer Choice (A). Just look at it. It says the argument is flawed because it treats a phenomenon as an effect of an observed change in the face of evidence indicating that it may be the cause of that change. The quick way to eliminate (A) is to recognize that this is a cause-effect confusion flaw, a commonly recurring flaw in LR. But it’s not what’s happening here, as we discussed above. The mistakes here are (1) confusing static (no change) with dynamic (change) and (2) misattributed cause.

The slow and thorough method involves lassoing the abstract language in (A) to the tangible concrete language in the stimulus. How do we do that? We can begin by looking at “treats a phenomenon as an effect of an observed change.” What is the argument treating as an effect? The decreased quality of plumbing instruction. So that must be the phenomenon. And it’s treating that as the effect of “an observed change,” which must be the adoption of the new curriculum. But wait, is that really a “change?” The curriculum has been in place for several years already. This is already looking to be descriptively inaccurate.

Let’s keep going. How about “in the face of evidence indicating that decreased quality of plumbing instruction may be the cause of adoption of the new curriculum”? What evidence? This is also descriptively inaccurate. The only evidence we have from the stimulus is that something isn’t up to snuff about the school. There’s no evidence that the school saw a sharp drop in its quality of instruction and then decided that they needed to fix this by adopting a new curriculum.

Answer Choice (B) says that the argument uses a lack of evidence that the quality of the school’s plumbing instruction has increased as though it were conclusive evidence that it has decreased. No, it doesn’t. It’s true that there is a lack of evidence of increase. But that’s not what the argument uses. The argument uses the presence of static evidence, the 33% pass rates, as if it were evidence of change. Also descriptively inaccurate.

Correct Answer Choice (C) can, fortunately, be analyzed in terms of premise descriptor and conclusion descriptor. It says that the argument “concludes that something has diminished in quality…” and indeed this is descriptively accurate. The argument concludes that the plumbing instruction has decreased in quality. “From evidence indicating that [plumbing instruction] is of below-average quality.” This is an accurate description of the premises. The evidence is the 33% pass rates. Does that indicate that plumbing instruction is of below-average quality? Not definitively, as I already noted above, but evidence doesn’t have to be definitive. And this is evidence of poor instruction. (C) also captures the move from static (low-quality instruction) to dynamic (decreased quality) that’s at the heart of this bad argument.

Answer Choice (D) says that the argument uses a national average as a standard without specifying what that national average is. This is true! Descriptively accurate! But it doesn’t matter because the argument isn’t weak for failing to specify just how many percentage points below the national average is “well below.” Imagine if the argument had told us what the national average was. Say it was 50%. The school’s pass rate is 33%, which is “well below.” Okay, is the argument better now? No. Because that was never the issue. Imagine again that the national average was 75%. The school’s pass rate is 33%, again “well below.” Is the argument better now? Or is the argument even substantively different now? No and no, because it doesn’t matter precisely how much below is “well below.”

Answer Choice (E) says that the argument confuses a “required” factor with a “sufficient” factor. This is the classic sufficiency-necessity confusion. That’s the oldest mistake in the book. That’s not what’s happening here. We’d have to do major reconstructive surgery on the argument for (E) to be right. We’d have to argue that the quality of a school’s curriculum is essential in the improvement of their graduates' pass rates on the national exam. Therefore, a school can expect to see improvements in pass rates simply by adopting a quality curriculum. That would be mistaking a necessary factor with a sufficient factor.