LSAT Question Explanation
PT 108, Section 2, Question 9
Helpful to KnowArgument structure
If the phenomena in China were caused by volcanic ash in the atmosphere, then the ash from Mt. Etna's eruption must have spread very far.
Ash from volcanic eruptions can block sunlight and cause temperature drops for over a year. In 44 B.C. Mt. Etna erupted in Sicily, and the following year people in China recorded summer frosts and relatively low sunlight.
Explanation
There's information missing from this argument. Sure, the phenomena recorded in China seem like they could have been caused by volcanic ash, but why does it have to be from the eruption of Mt. Etna? What if there was a volcanic eruption in East Asia, and the ash didn't have to travel far to cause the phenomena in China?
Answer choices
This information about modern monitoring equipment doesn't affect the argument, which is about events that happened over 2,000 years ago.
The stimulus just tells us that volcanic ash in the atmosphere can affect temperatures for a year or even more. The temperature changes don't need to last for over 1 year to be attributable to volcanic ash, so whether the changes in China lasted more or less than 1 year doesn't matter.
This doesn't affect the conclusion, which is that the ash from Mt. Etna traveled a great distance and caused the changes in China. Mt. Etna is in Sicily, so the temperature dropping in Sicily doesn't tell us that the ash traveled a great distance.
This would be very useful to know. If there was a volcanic eruption near China then maybe the phenomena they experienced weren't due to ash traveling from Mt. Etna, but rather from a nearby eruption.
This doesn't tell us if the ash traveled far, and doesn't even necessarily relate to the year described in the stimulus.