Q4 - There are only two possible reasons

[Laura Damone]

Question Type:
Sufficient Assumption

Stimulus Breakdown:
Main Conclusion: It would not be wrong to mine on Mars. Premises: There are only two reasons not to pollute - it harms ecosystems, which are valuable in themselves, or it would harm human populations. Mining Mars would pollute, but human miners wouldn't be harmed.

Answer Anticipation:
The first premise gives us the only two reasons not to pollute, but the second premise only rules out one (harm to humans). In order to conclude that it's ok to pollute Mars, we need to rule out the other (harm to ecosystems).

Correct answer:
B

Answer choice analysis:
(A) Beware comparative answer choices in Assumption questions that aren't about comparisons. Ranking language such as "less…than" is a red flag. Furthermore, the fact that mining doesn't pollute as much as some other stuff we do doesn’t prove that it's OK to mine Mars.

(B) Bingo! If there aren't any ecosystems on Mars, mining Mars can't harm an ecosystem. This rules out the only other reason not to pollute Mars, so we can OK the Martian Mining operation.

(C) This is a tricky one. Those who can't distinguish between Necessary and Sufficient Assumption questions are likely to be tempted by this, because it puts forth a cost/benefit analysis that one might reasonably assume to be necessary before undertaking any expensive economic venture. But if you look closely, the conclusion of the argument isn't a recommendation that we should mine Mars. It's an evaluation that it wouldn't be wrong to do so. A cost/benefit analysis isn't necessary in order to make a moral judgment of that sort, so this answer isn't actually necessary either.

(D) Like C, if you were looking for a Necessary Assumption, and if you mistook the conclusion for a recommendation rather than an evaluation, this would be a tempting one. But since we're not recommending action, we don’t need it to be feasible, and, more importantly, this is a Sufficient Assumption question!

(E) Another irrelevant comparison! Ranking language "more valuable" is a red flag, and, as with A, this simply doesn't prove the conclusion to be true.

Takeaway/Pattern:
Know your Assumption questions! Sufficient Assumption questions often have trap answers that are necessary but not sufficient, and Necessary Assumption questions often have trap answers that are sufficient but not necessary!

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