#21 - Essayist: When the first prehistoric migrations of

[Brook Miscoski]

Michael,

D strengthens the argument or is irrelevant, when the task is to weaken.

How?

Humans can carry diseases without suffering--explains one way that humans who weren't themselves dying off could cause an epidemic.
Animals can carry diseases without suffering--again, explains how animals following the humans and native animals could spread the disease before they died.

Alternatively, as you point out, what an "individual" human or animal can do does not explain an extinction event, so you could write the choice off as irrelevant or unclear as to its effect.

[lina2020]

The premise says: "It is implausible that hunting could have had such an effect" which is the premise, and C points to Hunting being the cause of the extinction - so are we not here attacking the premise? which is something we shouldn't do? as in we should believe in the truth of the premises given by the arguments and think of conclusions as suspicious?

The post above was my question exactly. I was able to select the right answer choice by process of elimination but couldn't help but wonder why it's correct given that it's a direct attack of a given premise. Please advise.

[KelseyWoods]

Hi Lina!

It's great that you're scrutinizing the stimulus in this way! In general, you're correct. We should trust the premises and instead question the conclusion drawn from those premises. In Weaken questions, we attack by showing that the conclusion doesn't necessarily follow from the premises rather than attacking the premises directly.

However, we have to consider the difference between "fact" and "opinion." Facts we accept as true, opinions we can usually question. This can be kind of a gray area on the LSAT because determining whether something is presented as a fact or as an opinion often has to do with context. Here, the author states "it is implausible that hunting by these small bands of humans could have had such an effect." In a sense, the author presents the statement as if it is a fact. But just stating that another explanation is implausible is really more of an opinion. If the author had given us actual facts as to why hunting was implausible as an explanation, then we could have believed those facts. But just telling us that hunting is implausible is simply the author's opinion. Opinions we can question.

As others have discussed above, this type of argument is actually fairly common on the LSAT. The author observes an effect (animal extinction) and concludes a cause (microorganisms). It's also pretty common for authors to deny an alternate cause (hunting). To weaken an argument like this, you can directly weaken the stated cause or you can strengthen the alternate cause (which ends up weakening the stated cause as well). Think of this argument as the author concluding: "The cause of the extinctions is microorganisms, not hunting." Answer choice (C) weakens it by saying: "Actually, it might be hunting."

Hope this helps!

Best,
Kelsey

[CristinaCP]

Hi!

I understand the reasoning behind why [C] is correct, but I'm having trouble understanding how [A] does not also conform to the "alternate cause" method of weakening a causal argument. [A] says that animals weakened by disease are less able to avoid hunters + predators. My reasoning was that [A] presents an alternate cause for the extinctions (in that the disease-causing microorganisms didn't cause the extinctions themselves, but just led to the "crucial factor" that directly caused the extinctions, like hunting or predators).

Can someone explain why this doesn't also weaken the argument? Am I misunderstanding something?

[Jeff Wren]

Hi Cristina,

In the argument, the stated cause is the disease-causing microorganisms and the stated effect is the extinctions.

Answer A describes a negative effect of diseases (namely weakening animals). The diseases (by way of the microorganisms) is part of the stated cause in the argument, so this would not qualify as an alternate cause just an alternate/additional effect.

The problem is that this answer is completely consistent with the conclusion of the argument. In other words, the microorganisms could still have caused the diseases, which weakened the animals (some of them were hunted by humans or other predators), but many of the ones that weren't hunted eventually died of the diseases. In which case, it would still be correct to describe the microorganisms as a "crucial factor" that accounts for the extinctions as the conclusion of the argument states.