Logical reasoning PrepTest 116 · Section 3 · Question 16

Incorrect. not Commonplace and ordinary → Miracles of nature. This negates one term but not the other, so it's a partial negation of what we need and is thus incorrect.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Sufficient Premise

Stimulus Summary:
Commonplace and ordinary → Fails to catch attention
Therefore — Fails to catch attention—some—Miracles of nature

Answer Anticipation:
Ah, the rare quantifier inference question framed as a Strengthen with Sufficient Premise question. We'll have to use the same skills as if this were a Must Be True question, only now we have to fill in the premise" that allows the conclusion to be drawn.

The premise and conclusion already share a term, so there's no need to take the contrapositive here. Instead, we need to figure out what terms need to be connected, what strength that connection needs to be, and (if it's not a some statement), what direction it needs to go in.

Let's start with what needs to be connected. The shared terms anchor the inference and "drop out" of it, so we don't need the correct answer to mention Fails to catch attention. Instead, we need to connect Commonplace and ordinary with Miracles of nature.

And, in fact, any strength statements would be correct here and allow the conclusions inference to be drawn! If it's stronger than a some statement, the direction will have to align with the argument, starting with Commonplace and ordinary and ending with Miracles of nature:
Commonplace and ordinary—some—Miracles of nature
Commonplace and ordinary—most—Miracles of nature
Commonplace and ordinary → Miracles of nature

Answer Explanation:
This answer reflects our anticipation. If some commonplace/ordinary things are miracles of nature, and all commonplace/ordinary things fail to catch our attention, then some things that fail to catch our attention are miracles of nature.

Key Takeaway:
These Strengthen with Sufficient Premise questions that involve conditional logic can be complicated. Start by diagramming everything out and taking contrapositives as needed to get terms overlapping. Figure out the gap—the terms that need to be connected—and then worry about how strong the statement needs to be.

Incorrect. This is a weaker version of the opening conditional, so it can't serve to justify the conclusion.

Incorrect. This answer is a reversal of the opening premise.

Incorrect. Let's be generous and diagram this as: not Fails to catch attention → not Commonplace and ordinary. That's just the contrapositive of the opening conditional, so it adds nothing to the argument.