Logical Reasoning

PT121 · S1 · Q17 Some classes of animal are

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Some classes of animal are so successful that they spread into virtually every ecosystem, whereas others gradually recede until they inhabit only small niches in geographically isolated areas and thereby become threatened.

Conclusion

No species of ant is a threatened species.

Evidence

Ants are insects, a class of animal that spreads into virtually every ecosystem, and ants are the most successful insects.

Evaluate

Even if insects rule, and ants are the #1 type of insect, it still seems possible that some (at least one) species of ant is threatened.

Maybe there's a specific species that lives in the melting Arctic and is about to lose its habitat.

Goal

Look for something saying, .

It's kind of a Whole to Part move, in the sense that the author thinks that because ants as a whole are so successful, each ant species must be successful.

17.

The argument is flawed because it takes for granted that

  1. the Arctic Circle and Tierra

    Out of Scope: geographically isolated

    The author merely brings up these two examples as rhetorical way of saying "from Pole to Pole", from the far North to the far South of the globe. It doesn't matter whether they're geographically isolated or connected.

    5% picked this

  2. because ants do not inhabit

    Too Strong: most

    We can't say whether the author would say ants are or aren't like 51% or more of insects. Given that insects are identified as a very successful class, it's plausible that most of them inhabit a wide swatch of geographical areas, just like ants.

    2% picked this

  3. the only way a class

    Too Strong: only

    The author doesn't need to assume that there's one and only one way to avoid being threatened.

    9% picked this

  4. what is true of the

    Reversed

    This argument said, because it's true of the whole (ants, as a type of insect), it's true of the constituent elements (each ant). This says the reverse.

    16% picked this

  5. Correct

    what is true of a

    Why this is right

    What's true of the whole family of ants is that they are super successful. In concluding that every single ant species is unthreatened, the author is assuming that each any species must be super successful.

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

    68% picked this

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