LSAT 70, Logical Reasoning I, Q9

QUESTION TEXT: Astronomer: Proponents of the hypothesis that life …

QUESTION TYPE: Flawed Reasoning

CONCLUSION: There is good reason to think that the hypothesis is false.

REASONING: There’s no evidence for the hypothesis.

ANALYSIS: I intentionally simplified the conclusion and reasoning to make the error clearer. You can’t conclude that something is wrong just because there’s no evidence to support it. To prove that something is wrong you need actual evidence against it.

The astronomer only has lack of evidence. He should have concluded “I don’t know if the hypothesis is right or wrong. I have no evidence for or against it.”

Instead, he assumes that the hypothesis is wrong. When you have no evidence, you can’t do that. You have to say “I don’t know”. Something can be right even if you currently lack evidence that it is.

Don’t let the science talk frighten you. Almost all of it is fluff. The entire argument is in the final sentence.

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1. CORRECT. The astronomer says there is ‘good reason’ to think that the hypothesis is false. Good reason = evidence. Why does the astronomer think that there is evidence against the hypothesis? In the final sentence, his only proof is that there is no evidence for the hypothesis.
2. The astronomer didn’t say that the hypothesis is inherently implausible. He just said that there’s currently no evidence for it.
3. The astronomer didn’t mention any hypothesis that is equally likely to be true.
4. Which premises contradict the conclusion? If the flaw didn’t happen, then an answer can’t be correct.
5. This isn’t a flaw. If your opponent makes a true claim, then you must grant that it’s true, even if it weakens your argument.

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