Logical reasoning PrepTest 125 · Section 2 · Question 21

Correct.Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Migraine suffering adults-most- Bouts of depression as kid
Therefore - Bouts of depression as kid-most- MIgraine suffering adult

Answer Anticipation:
Noting the logical force of these statements is going to be one of the keys to finding the correct answer. The premise here is a most statement, and the conclusion is a likely statement. "Likely" is at the same moderate logical force as "most," which is why we diagrammed the conclusion in the manner we did.

Diagramming it out also helps us to see the flaw in this argument. While it feels like a correlation/causation flaw, the conclusion is actually a correlation, as well—likelihood language denotes a correlation, not causation. But the issue is that the conclusion reverses the most statement, and that's not a valid inference (some statements can be reversed; most statements cannot).

Let's find an answer that matches the logical force of the statements while also reversing the logic of the premise in reaching the conclusion.

Answer Explanation:
GT dog-most- Rabies vaccination as puppy
Therefore - Rabies vaccination as puppy-most- GT dog
Same logical force, same reversal. This is the correct answer.

Key Takeaway:
The more relevant logical elements you can identify, the easier it is to make eliminations. While not every element needs to match up in a Flawed Parallel Reasoning questions, the elements related to the flaw do need to match up. Here, that included the logical force—if the conclusion were weaker (e.g., "A child prone to bouts of depression might suffer migraines . . . "), then it would be valid.

Incorrect. This answer matches the logical force, but it doesn't reverse the logic. Instead, it jumps from a discussion of what is true of dogs to what is true of their owners—the flaw being that the pet owner is the same as when the dog was a puppy.

Incorrect. The conclusion here doesn't match the logical force of the stimulus, so we can eliminate it.

Incorrect. The conclusion here is relative—"more prone"—so it's not parallel to the stimulus.

Incorrect. While the phrasing of this answer can make it seem as if it's reversing the logic, working through it shows that it is not:
Puppy-most-Taken from mother at 8+ weeks
Puppy that's 8+ week-most-Taken from mother
It does change up the structure a bit, but it does so in a manner that's valid, saying the same thing in two different ways. If most puppies are taken from their mom at 8 weeks, then most puppies who are at least that age have been taken from their moms.