QUESTION TYPE: Complete the Argument
CONCLUSION: We should not stop the tree-eating tussock moths.
REASONING: Moths are helpful where lack of forest fires has left forests full of immature trees. (And this forest is full of immature trees)
ANALYSIS: On complete the argument questions, you have to think about the logic of the argument, and then think about how to add to that logic.
Most of the wrong answers here are things that are merely consistent with the argument. But we don’t just want something true. We want something that strengthens the argument. (This is an unusual question stem – most complete the argument questions ask for a conclusion, not a premise).
Here, the author is saying moths help when forests have too many immature trees. And they’re saying we should allow the moths in this forest. That must mean that this forest has too many immature trees.
- CORRECT. This works. The argument says moths are useful when a forest has too many immature trees. So since the forest is full of
immature trees, we should leave the moths alone.
- This contradicts the logic of the argument. The author said that moths help when we have too many immature trees. The moths should be eating those trees, not the mature trees.
- This is just a fact that tells us what happens during forest fires, in general. It adds no information about the specific forest: we’re trying to decide whether to allow moths there, or not.
- So? We still have the option of countering the outbreak. This answer doesn’t tell us whether or not we should counter the outbreak.
- This answer is trying to make you think we can do nothing against the moths, but that’s not true. For example, perhaps we could stop 99.99999% of them, even if we don’t have a completely effective solution.
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