Logical reasoning PrepTest 114 · Section 1 · Question 11

Incorrect. The conclusion is about the purpose of grades, not the purpose of school, so this answer is out of scope.

Incorrect. The argument doesn't discuss students who are indifferent to the grades they receive, just students to whom grades don't serve enough of an incentive to learn something they dislike. The bad students could really care about grades without being willing to do something to earn good ones.

Incorrect. The conclusion limits the scope of the argument to discussing the academic purpose, so any nonacademic purpose is out of scope.

Incorrect. The argument is about grades, not choice of material to be studied, so this answer is out of scope.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Teachers: Students won't learn if you don't give them grades

Students with intense interest in material - Will learn regardless of grades
Students with no interest in material - Won't learn even with grades
Therefore - Grades serve no academic purpose

Answer Anticipation:
There are two elements in this stimulus that come together to let us identify the flaw.

The first is in the conclusion—it states that grades serve "no" academic purpose. If there's any purpose whatsoever, no matter how small, that's left open as a possibility after the premises are established, then that conclusion is unsupported. That's a tall order.

Looking at the premises, a common gap is created! Whenever an argument starts splitting a larger group up into subgroups, you should check to see if those subgroups are comprehensive—if they represent the entirety of the larger group. Here, since the conclusion is so strong, it's likely that the premises are going to neglect a group.

In the premises, the author discusses the best students and the worst students. However, she fails to consider all the students in the middle—those who don't have an intense interest in the subject matter but don't lack interest completely. For this group, grades might serve a purpose, and thus the conclusion that they serve no purpose is flawed. Let's find an answer discussing this overlooked group.

Answer Explanation:
This answer highlights the group that the author ignores—those who aren't intensely interested in the material but also don't lack all interest in it. Since grades may serve an academic purpose for this group, the failure to bring them up is a flaw in the argument.

Key Takeaway:
Whenever an argument starts splitting a group up into subgroups, check to see if the groups are exclusive and comprehensive. Exclusive means that they can't share members (which they couldn't here). Comprehensive means that they represent the entirety of the larger group when put together (which they didn't here). While both questions won't always be relevant to the question, it's good to note these things as a matter of course.