Logical reasoning PrepTest 115 · Section 4 · Question 21

Incorrect. If this answer were about the percentage of Moore's customers that haven't filed complaints, then it might be relevant. But talking just about their interests doesn't tell us if the complaints filed reach a critical mass to allow a judgment to be drawn about Moore's poor plumbing.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
All complaints about plumbers are about Moore, so he must be really bad.

Answer Anticipation:
The conclusion here is that someone is a bad plumber, and this is based on complaints filed. Before we dig into the specifics of the complaints, let's think about what we would want to see before we'd believe Moore is a bad plumber based on them.

We all know that having complaints doesn't mean something is bad—some people just have bad experiences with even good things. So what matters is whether these complaints are repeated and whether they represent a large amount of Moore's business. If, say, there are a dozen complaints, but Moore does four or five jobs a day, then those dozen complaints are small compared to all the work he did that didn't lead to a complaint.

Looking at the premises here, we only see that "every complaint filed" was about Moore. That doesn't establish that there were a lot of complaints! Maybe the town has had only two complaints filed over the past decade, and so Moore's two complaints are a pretty good rate. If other plumbers work in the area, maybe they're better than Moore, but that doesn't mean he's bad. And that brings up another possibility—that Moore is the only plumber in this small town. In that case, of course there are no complaints about other plumbers, as there are no other plumbers.

We're looking for an answer that brings up a possibility the argument "fails to consider," so let's look for something that lines up with one of those possibilities we just highlighted.

Answer Explanation:
If there aren't any other plumbers in town, then Moore receiving all the complaints makes sense even if he's the best plumber on the planet. Even if there are just a few others, the same could hold—he may not be as great as the others, but he could still be relatively good. This answer is therefore correct.

Key Takeaway:
This is one of those questions where if you see the "trick" to it quickly, you'll have an easy time. If you didn't see the "trick" here, be sure to review it to walk through the logic and process of what we did so that you're more likely to see it in a similar question in the future.

Incorrect. No matter how big or small a plumber's business, it can still have its quality judged. The conclusion also isn't really a generalization—it's a condemnation of Moore's skills!

Incorrect. This answer might tell us whether Moore's town is full of people who like to complain, but that wouldn't tell us if they're right or wrong, or if there are enough of them complaining about Moore to draw a conclusion about his skill level as a plumber.

Incorrect. If everyone who was dissatisfied filed a complaint, then counting up the complaints would give a good view as to how many people didn't like the job Moore did, which would help in evaluating the conclusion. If some people who were dissatisfied with Moore's work didn't file a complaint, then counting up the complaints would set up a minimum number of complaints, and if even that led to questions on his ability, then the real number would do even more so. As such, not considering this possibility doesn't make a difference in the logic of the argument, so it's incorrect.