Logical Reasoning

PT156 · S4 · Q12 Ecologist: El Niño, a global weather

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Ecologist: El Niño, a global weather phenomenon that occurs once every several years, is expected to become more frequent in coming decades due to the global warming caused by air pollution.

Conclusion

Average rodent populations will increase in region T in the coming decades.

Evidence (since)

The argument suggests a chain of causation: air pollution causes global warming, which leads to more frequent El Nino's. More El Ninos cause increased heavy winter rainfall, leading to long periods of sustained rain, which typically increase rodent populations.

Evaluate

This is a "Weaken" question, and the aim is to find an answer that undermines the prediction made in the conclusion. To weaken the argument, we need to disrupt the causal chain that links global warming and increased El Nino's to more rodents through heavy sustained rain.

Goal

Identify the answer choice that effectively challenges any part of the causal chain, thus casting doubt on the prediction of increasing rodent populations.

12.

Which one of the following, if true, would most weaken the ecologist's argument?

  1. In region T, there is

    Irrelevant

    This choice compares rain patterns between seasons in region T, but it doesn’t affect the prediction about future rodent populations. If there's more rain in winter, then we'd predict rodent populations to surge in winter, but this doesn't have anything to do with whether those surges will be bigger/smaller/same in coming decades.

    1% picked this

  2. Rodent populations in region T

    Opposite (if anything)

    This "less rain, less rodents" type of answer seems to corroborate the argument's correlation between rodents and heavy rain. So if anything it would strengthen.

    3% picked this

  3. In many regions that, on

    Unclear Impact

    This seems somewhat promising, because it sounds like it's decoupling the argument's link between heavy rain and higher rodent populations. But since we're comparing different regions, we don't know what other factors might be contributing to there being lower rodent populations in regions with more rain. If rain is good for rodents, but snakes are bad for rodents, a region with lots of rain and lots of snakes could potentially have fewer rodents than a region with less rain but no snakes. To undermine the rain/rodent link, we'd want to hear "within a given region, the rodent populations were lower when there was lots of rain than when there was much less rain".

    15% picked this

  4. Correct

    In region T, winters marked

    Why this is right

    We know that El Nino causes heavy winter rainfall, but the trigger the Evidence provides for a boost in rodent population is a long period of sustained rain (like it rains for 5 days straight), not just heavy winter rain. This answer shows how coming decades could have heavier winter rainfall but not actually have any uptick in long periods of sustained rain. This provides disconnect in the causal chain the author was selling us.

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

    73% picked this

  5. The global warming caused by

    Unclear Impact

    While stating that global warming could have other effects on rodent populations, it doesn’t specify whether these effects would increase or decrease rodent numbers. Consequently, it creates uncertainty but doesn’t directly weaken the argument since the net effect is unclear.

    9% picked this

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