Logical reasoning PrepTest 149 · Section 4 · Question 2

Incorrect. There being even more mammals to compete with the birds would only reinforce the conclusion that the theory on why birds were rich and varied on the island is wrong.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Weaken

Stimulus Summary:
New Zealand was believed to not have indigenous mammals, but a recent fossil discovery has shown that it did. Therefore, the theory that the bird population of NZ thrived because of a lack of mammalian competition is wrong.

Answer Anticipation:
Animals compete for resources when they live in the same habitat at the same time. If this mammal was around the birds, then it was competing with them, thus falsifying the theory that the author attacks. In order to weaken this attack, then, the correct answer will have to go after the cohabitation of the mammal and birds. It could state that the mammal was limited to areas where the bird population doesn't live, though even that might suggest that the mammal drove the birds out through competition. More likely because we're talking about fossils is that the mammals were around at a time when the birds weren't—they're from before the first known bird species was found in NZ.

Answer Explanation:
If the mammal wasn't around at the same time as the birds, then there was no competition and thus this mammal doesn't serve as evidence against the theory. Since the argument is designed to call that theory wrong, this answer weakens the argument.

Key Takeaway:
Whenever the LSAT starts digging into the fossil record, it's dealing with very, very long timelines. That leaves open plenty of room for any individual event or time period to not overlap with others.

Incorrect. The conclusion is about a theory that birds thrived because there was no mammalian competition, so other types of animals are out of scope.

Incorrect. The discovery in NZ is of a single mammal, so this answer can't be said to apply to NZ. And if you were thinking that it showed another example of a relationship between more mammals and fewer birds, it does—which supports the theory that the argument is designed to falsify.

Incorrect. This answer really doesn't have any impact on the argument, but, if anything, it aligns with the fact pattern.