Q9 - Gecko lizards are found

[smiller]

Question Type:
Flaw

Stimulus Breakdown:
Premise: abundant gnats → gecko lizards
Premise: gnats survive → wet climate
Premise: no gecko lizards here
Intermediate Conclusion: not abundant gnats
Conclusion: not wet here

Answer Anticipation:
The second premise lets us infer that if the climate is not wet, gnats cannot survive. To arrive at the conclusion we need to infer that if there are no gnats, the climate is not wet. We can't infer that. Maybe the climate is wet, but there are no gnats because it's too cold for them to survive. So, the argument contains a conditional logic flaw.

Even if we could infer "no gnats → not wet climate," there would still be a flaw in the argument. Stating that there is not an abundant gnat population is not the same as stating that gnats cannot survive at all, so we still couldn't arrive at the conclusion based on the intermediate conclusion. To reach the conclusion of this argument, we need to assume "not abundant gnats → not wet climate."

Correct answer:
(B)

Answer choice analysis:
(A) Wrong Flaw: This would be an invalid reversal of the first premise, but the argument doesn't incorrectly reverse that premise.

(B) Correct: This is the contrapositive of the assumption we predicted above: wet climate → abundant gnats.

(C) Wrong Flaw: Using the contrapositive of the second premise, we can infer that if a climate is not wet, gnats cannot survive. Answer choice (C) describes a situation that would contradict this inference. This isn't something that the argument needs to consider.

(D) Out of Scope: The argument never actually states anything about gecko lizards eating gnats. We know that if there are abundant gnats then we will find gecko lizards, but we're never told why. Maybe the geckos like to keep gnats as pets. (If you picked this answer, imagine a horrified gecko standing next to his beloved pet gnat, staring at you disapprovingly.)

(E) Let's look at this answer piece by piece. "Fails to establish" means assumes. Does the argument assume anything about gecko lizards not surviving in a dry climate? No. The argument assumes that if there are not abundant gnats then the climate is not wet. We don't have to assume anything about gecko lizards in this argument.

Takeaway/Pattern:
Geckos, gnats, and climates, oh my! The stimulus in this question tries to confuse us by switching between statements about gnats and statements about geckos. The answer choices do the same thing. It's essential to have a clear understanding of both the conditional logic in the question and the exact assumption. Without that clear understanding, several of the answers might look tempting.

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