October 2004 LSAT Section 4 Question 17

Climatologists believe they know why Earth has undergone a regular sequence of ice ages beginning around 800,000 year...

Williamg on August 14, 2022

Why not C?

I see why D is correct, but doesn't C weaken the argument by offering volcanoes as an alternative explanation for the ice ages?

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christine.macke on September 13, 2023

I have the same question, please explain

Emil-Kunkin on September 14, 2023

C would certainly weaken if it said that volcanic eruptions happened at an increased rate around the same times that the ice ages occurred. However, we don't know this and we have absolutely no reason to think that this is the case. In the absence of a reason to think that eruptions occurred around the same time as the ice ages, we cannot say that this is an alternative cause in this case. However, it could be proof of concept that dust can indeed cause temperatures to fall.