#21 - Although the geological record contains some hints of

[Overthinker99]

I fully understand why A is correct. It takes the premise makes it the sufficient, and the conclusion the necessary byproduct (via the contrapositive).

What I can not wrap my head around is how B does not do the same thing. Translating B into conditional logic, we have: "/many mass extinctions were caused by meteorite strikes—>Can not be causally linked"
Our first premise that "many mass extinctions were not caused by meteorite strikes" is certainty fulfilling the sufficient condition here, is it not? It is the natural flip side of the coin.

If not many extinctions were caused by meteor strikes, then naturally many mass extinctions were not caused by meteorite strikes. I understand "many" is a mushier word, but "many" and "not many" are proper negations.

[Jeff Wren]

Hi Overthinker,

The word "many" is the bane of "many" LSAT test takers, and this question provides a perfect example.

What does "many" really mean? It doesn't mean "most," even though a lot of test takers mistakenly assume that it does. How many is many? Hard to really say. It's a very vague term that can only be described as "more than a few." I mention this because you should always be wary of the word "many" whenever it appears on the LSAT. It has a bad habit of showing up in a lot of wrong answers.

You wrote:

Our first premise that "many mass extinctions were not caused by meteorite strikes" is certainty fulfilling the sufficient condition here, is it not? It is the natural flip side of the coin.

Unfortunately, that's not right. "Many" is tricky that way.

For example, I can say with a high degree of confidence that "Many people like pepperoni pizza." I can also say with a high degree of confidence that "Many people do not like pepperoni pizza." These statements are not opposites and can both be true together (and in fact are true).

In our argument, we would need to show that "it is not the case that many mass extinctions have followed major meteor impacts" in order for Answer B to justify this argument. In other words, we'd need to show that there have been few (or zero) mass extinctions that have followed major meteor impacts.

Knowing that "there were many extinctions that did not follow any known major meteor impacts" doesn't tell us anything about the number of extinctions that did follow major meteor impacts in the same way that knowing that many people like pepperoni pizza doesn't tell us anything about the number of people who do not like pepperoni pizza. Since "many" doesn't imply "most," for all we know there could be even more mass extinctions that did follow major meteor impacts than there were that didn't follow major meteor impacts.