PrepTest 143

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
Phenomenon Ð Red admiral butterflies fly in an irregular fashion that's not energy efficient
Context Ð Poisonous butterflies are avoided by predators; non-poisonous butterflies like the red admiral need to elude predators
Hypothesis Ð The weird flying pattern evolved to help them avoid predators

Answer Anticipation:
This argument falls into a common structure—a phenomenon and a hypothesis meant to explain that phenomenon. When that's the case, the correct answer generally deals with an alternative explanation for the phenomenon—and, in a Strengthen question, it will generally rule that alternative explanation out.

Here, the explanation for the weird flight pattern the red admiral developed is that it's using it to elude predators. Any other reason that the weird flying may have evolved will serve to weaken this argument, so the correct answer should provide evidence against an alternative possibility.

Answer Explanation:
This answer suggests an alternative reason that the red admiral butterfly evolved to fly this way—to mimic a poisonous butterfly. If there were a poisonous butterfly that flew similarly, then the red admiral may have evolved to appear to predators as a poisonous butterfly, not to elude predators. In ruling out that possibility, this answer strengthens the argument.

Key Takeaway:
Phenomenon/explanation (hypothesis) arguments are common on the LSAT, and the correct answers generally deal with alternative hypotheses/explanations. While it's probably not worth your time to think up a few alternatives—especially in a science-heavy passage that's most likely outside your area of expertise!—it is worth it to recognize this structure and anticipate an answer that raises an alternative.

Incorrect. Even if they're not the most common cause of death, they could still be a common one that put evolutionary pressure on the species, resulting in a defense evolving.

Incorrect. Without knowing if these are poisonous or nonpoisonous, and if the weird flight style in those species was or wasn't evolved in response to predation, we can't say what impact this answer has on the argument.

Incorrect. This answer, in bringing up the energy efficiency of other species, is out of scope, especially since we already know that it is energy inefficient for butterflies to fly in this manner.

Incorrect. Without knowing anything about how these other species attempt to avoid predation, it's hard to know if this has any impact on the argument.