LSAT 128 | Section 2 | Logical Reasoning: Q13

LR Question 13 Explanation

QUESTION TEXT: Scientist: There is little doubt that the ice ages were …

QUESTION TYPE: Identify the Conclusion

CONCLUSION: Excessive vegetation growth most likely caused the ice ages.

REASONING: Excessive vegetation growth would have depleted atmospheric CO2, which helps retain the sun’s heat. With less CO2, the Earth would cool significantly, causing an ice age.

ANALYSIS: This question is very straightforward if you can recognize that the first sentence is the conclusion. The correct answer will just restate this causal claim, while preserving the scientist’s confidence (“little doubt”).

Everything else (the causal chain) just acts as an explanation for the conclusion. It says that excessive vegetation -> less CO2 -> less heat retention -> ice age. But this is just evidence in support of the conclusion (which is the first sentence).

___________

1. “Could have caused” is too weak. The scientist says there’s little doubt, not that it’s just a possibility.
2. This is a premise, not the conclusion. Read the analysis above – it’s a part of the explanation that supports the conclusion, not the conclusion itself.
3. Same as B, this is another premise.
4. This frames the claim as a conditional statement rather than a direct claim. The scientist doesn’t just say if vegetation caused the ice ages, it did so by depleting CO2. He asserts very strongly that vegetation caused them.
5. CORRECT. This directly states the first sentence, which is the argument’s main claim. “Almost certainly” reflects an equal type of assurance as “there is little doubt”.