LSAT 108 | Section 2 | Logical Reasoning: Q9

LR Question 9 Explanation

QUESTION TEXT: Very powerful volcanic eruptions send …

QUESTION TYPE: Evaluate the Argument

CONCLUSION: If the Chinese frosts and dimmed sunlight were caused by volcanic ash, then Mount Etna’s ash must have spread very far.

REASONING:

• Powerful volcanic eruptions can send ash into the atmosphere, causing cold temperatures and dimmed sunlight.
• Mount Etna erupted in 44 B.C.
• The following year, China experienced summer frosts and dimmed sunlight.

ANALYSIS: The conclusion is careful. It doesn’t say the Chinese weather WAS caused by Mount Etna’s ash. It says if it was caused by volcanic ash, it was Mount Etna.

So they’re identifying which volcano is responsible if it was a volcano.

The biggest alternative explanation, then, is whether it could have been from a different volcano. Maybe the Chinese weather was caused by volcanic ash from a different, much closer volcano.

After all, Mount Etna is in Sicily. Italy is quite far away from China.

If there was another eruption near China around that time, then the evidence for long-distance travel from Sicily becomes much weaker. If there wasn’t, then the argument becomes much stronger.

So to evaluate the argument, we want to know whether there might have been other volcanic eruptions closer to China.

___________

1. Modern monitoring equipment didn’t exist in 44 B.C. Even if it did, whether we can precisely track ash today doesn’t tell us whether Etna’s ash caused the Chinese weather.
2. We don’t need the abnormal weather to last a full year. Even a shorter period could still have been caused by volcanic ash.
3. The conclusion is about whether ash traveled to China, not whether Sicily also got colder. Even if Sicily stayed warm, the ash still could have traveled east.
4. CORRECT. This directly addresses the biggest alternative explanation: other volcanoes that could have caused the weather.
5. Subsequent eruptions of Mount Etna don’t matter. We’re evaluating one specific eruption in 44 B.C.