Logical Reasoning

PT136 · S2 · Q11 In the last year, biologists

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In the last year, biologists have learned that there are many more species of amphibians in existence than had previously been known.

Conclusion

It looks like pollution is not eliminating many amphibian species each year.

Evidence

In the past year, we've learned that there are many more species of amphibians in existence than we previously thought.

Evaluation

Given that last yr we realized there are more A species than we previously thought, How could we still say that pollution is eliminating many A species each year?

Maybe we can see amphibian species disappearing from the Gulf of Mexico, but we discovered a bunch of new amphibians on the Galapagos Islands.

It certainly seems possible that scientists could simultaneously discover new amphibian species while witnessing known amphibian species in decline elsewhere.

Goal

Since the question stem is predicated on "the author has confused ____ with ____ " language, how would we express the author's flaw in terms of confusion?

She seems to think that "# of amphibian species is not going down" because . The confusion is that just because we now realize a species exists doesn't mean it adds to the total species of amphibians on Earth. Those species existed on Earth even before we discovered them.

To assess whether the environmentalists' claim is true, we would need to know If we just discovered 100 new species, we would retroactively add that to the total of last year as well, because they also existed then (we just didn't realize it).

So, there's a confusion between "the total # of amphibian species on Earth" vs .

11.

The reasoning in the argument above is most vulnerable to criticism on the grounds that it involves a confusion between

  1. kinds of things and the

    Not an Objection

    What does this distinction even mean? "Cereals" is a kind of thing, and Lucky Charms and Cheerios are things that are of that kind. Was the author confusing a category name, like "amphibians", with specific species of amphibians? No, that wasn't the problem.

    4% picked this

  2. a condition necessary for a

    Wrong Flaw

    There was no Conditional Logic in this argument, so we should not be describing the problem with the argument as "messing up conditional logic" (aka, Necessary vs. Sufficient)

    3% picked this

  3. a cause and an effect

    Wrong Flaw

    There was a not a correlation in which the author concluded X caused Y, when in reality Y caused X.

    3% picked this

  4. a correlation between two phenomena

    Wrong Flaw

    The author doesn't go from a correlation between two factors to a causal conclusion/assumption about those two factors. The author's argument is purely about numbers of amphibian species, so the flaw here is mathematical / statistical, not causal.

    13% picked this

  5. Correct

    changes in our knowledge of

    Why this is right

    Last year, our knowledge of how many amphibian species there are changed (we discovered 100 new ones on the Galapagos Islands, for example). Bur those weren't newly formed species. Those amphibians we now know about didn't go from not-existing to existing, hence they have nothing to do with the environmentalists' claim that more amphibian species are going extinct each year. We can't say, "yeah 75 species went extinct, but 100 new ones were added", because 100 new ones weren't added to Earth, they were just added to our list of amphibian species we know about.

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

    76% picked this

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