Logical Reasoning

PT131 · S2 · Q21 Essayist: When the first prehistoric

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Essayist: When the first prehistoric migrations of humans from Asia to North America took place, the small bands of new arrivals encountered many species of animals that would be extinct only 2,000 years later.

Conclusion

Microorganisms on the new humans and their new animals is probably what led to a bunch of animal extinctions that occurred about 2000 years after these humans arrived in North America.

Evidence

It's implausible that hunting from these small bands of humans could have caused so many extinctions. Also, the new arrivals and their animals definitely had foreign disease-causing microorganisms on them.

Evaluation

If we want to weaken a causal hypothesis, we have to either have a different way to explain the Curious Fact or think of a way to render the author's hypothesis less plausible.

What else could have caused the extinction of many North American species, 2000 years after the arrival of humans? Maybe climatic stuff. Maybe some change in the local predator / prey dynamics. Maybe humans still caused the extinctions, but not via causing diseases or overhunting.

What would make the author's hypothesis that microorganisms from Asia led to the extinctions less plausible? Maybe the new microorganisms didn't cause any diseases virulent enough to cause extinctions. Maybe the diseases were just one of a few things, not "the crucial factor".

Goal

We need an answer that offers a different explanation for the extinctions, or an answer that undercuts the plausibility that disease-causing microorganisms were the crucial factor in the extinctions.

21.

Which one of the following, if true, most weakens the essayist's argument?

  1. Animals weakened by disease are

    Opposite / Strengthens

    This adds plausibility to the idea that disease was the crucial factor, since it points out that disease also exacerbates other threats such as hunters and animal predators.

    10% picked this

  2. Human beings generally have a

    Too Weak

    Yeah, we have a substantial immunity of other species, but our blind spot is usually species from other ecosystems. To this day, when people travel to far away countries, they tend to avoid drinking the local water because the local microorganisms are foreign to their guts. We already know from a premise that in the case of the newly arriving humans/animals there were disease-causing microorganisms. So we're not going to wriggle out of this author's conclusion by making it seem like North Americans were immune to these new agents.

    2% picked this

  3. Correct

    Very few species of North

    Why this is right

    This answer makes hunting seem like the crucial factor. If very few of the non-hunted species went extinct, then it sounds like whether you were hunted or not was a big causal difference-maker. This answer is weird since it seems to just go against the author's idea that "it's implausible that hunting could have such an effect", but that's our author's opinion. If this answer is true, then it's certainly raises our doubt about whether we should crown "disease" as the primary cause of extinctions.

    Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.

    65% picked this

  4. Individual humans and animals can

    Strengthens, if Anything

    Words that only guarantee "at least one case", such as could, may, might, some, sometimes, not all, are usually wrong on Strengthen, Weaken, and Paradox. Plus, the idea that you could carry a disease without suffering from it actually helps the author's hypothesis by reassuring us that the humans coming from Asia would be able to make the trip, even while carrying a disease.

    16% picked this

  5. Some species of North American

    Too Weak

    Too Weak: "some" Out of Scope: "more than 2000 years after" It's a total "so what" fact to bring to this conversation that "at least one species of animal went extinct more than 2000 years after humans arrived". Of course at least one went extinct. We assume that many species still go extinct to this day, which is way later than 2000 years after humans arrived.

    8% picked this

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