Logical reasoning PrepTest 146 · Section 1 · Question 16

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Argument Completion (Strengthen)

Stimulus Summary:
A tussock moth outbreak is beneficial where forests are unnaturally crowded with immature trees, and __________, so the expected outbreak shouldn't be stopped.

Answer Anticipation:
The argument concludes that a certain event should be allowed to take place because it's beneficial under certain circumstances. To strengthen that argument, then, it should be established that those circumstances apply to the current case! The correct answer should establish that in most of the forest, suppression of forest fires has resulted in overcrowding with immature trees.

Answer Explanation:
This answer establishes that the situation under which a moth outbreak is beneficial applies in most of the forest, thus justifying the recommendation to let the outbreak happen.

Key Takeaway:
While this stimulus isn't conditional, the flaw in the argument very much is related to one that we commonly see in conditional arguments. There, outside of conditional logic flaws, arguments that try to apply the conditional to a specific instance commonly fail to establish that the sufficient condition is met in that instance. Here, similarly, it's established that something is beneficial in certain cases, but it fails to establish that this case falls into that category. Always make sure that the argument establishes that the relevant premises apply in any specific case being discussed!

Incorrect. Without knowing the makeup of the forest in question, this answer doesn't help. That said, if anything, it suggests a reason that the tussock moths might not be beneficial in a mixed growth forest, which cuts against the recommendation in the conclusion without knowing more about the forest.

Incorrect. This might explain why suppression of forest fires can lead to a problem, but it doesn't establish that the forest in question has that problem.

Incorrect. This answer doesn't add much since the recommendation was to do nothing to stop it. It also doesn't establish that they'll be beneficial to this forest.

Incorrect. If anything, this is a reason to prevent an outbreak if possible since once they're out there isn't a way to completely counter them.