Logical reasoning PrepTest 144 · Section 3 · Question 9

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Errors in Reasoning

Stimulus Summary:
Opposing hypothesis: Life came here from outer space (because reasons)Astronomer: They haven't offered reason to believe life is from outer space spores, so there's reason to think that hypothesis is false.

Answer Anticipation:
All of the complexity and hard science in this stimulus is presented as a part of the opposing hypothesis, but we're tasked with finding a flaw in the Astronomer's argument. As such, we should only dig into the logic of that opposing point if we have to—if the logic in the Astronomer's logic is flawed in some way that it references that other point.

Luckily, that doesn't happen! The Astronomer's conclusion is that there's reason to believe a hypothesis is false. What evidence does she have against that hypothesis? None. Instead, she points out that the people who believe it haven't offered any actual support for it. There failing to be an argument or proof in favor of a hypothesis isn't evidence that the hypothesis is false—just that it might be. This is a common error in reasoning on the LSAT—an absence of evidence flaw.

Answer Explanation:
This answer is the generic absence of evidence answer. A lack of evidence in favor of a theory can't be used to disprove the theory, or as evidence that the theory is false. There has to be affirmative evidence against the theory for that to be the case!

Key Takeaway:
A lack of support for an opposing view, or a flaw in the argument supporting that view, can justify a conclusion that the view might be false, but it doesn't provide evidence that it is false. That's an absence of evidence flaw.

Incorrect. The Astronomer doesn't claim that the view is inherently implausible, but rather that its proponents don't offer any proof of it.

Incorrect. While the Astronomer does conclude that there's good reason to view the hypothesis as false, it's due to a lack of evidence supporting it, not because of an equally likely hypothesis. If anything, the Astronomer accepts the evidence against that theory put forward by the proponents of the extraterrestrial theory in stating that they offer empirical evidence against the terrestrial theory.

Incorrect. There's no premise that says the extraterrestrial theory of life on Earth is true, which would be necessary for the conclusion to contradict the premises.

Incorrect. Conceding valid/true points to an opposing point isn't a flaw in an argument.