PrepTest 121, Section 1, Question 17
Some classes of animal are so successful that(57 more words not shown)
The argument is flawed because(5 more words not shown)
- Athe Arctic Circle(10 more words not shown)
- Bbecause ants do(17 more words not shown)
- Cthe only way(15 more words not shown)
- Dwhat is true(13 more words not shown)
- Ewhat is true(10 more words not shown)
Reading the argument
Ants can be doing very well overall while one kind of ant is in trouble.
The passage describes ants spread across a huge geographic range. That tells us something about the group. It doesn't tell us that every species occupies that whole range. Imagine many flourishing species spread across the world, alongside one species restricted to a small, isolated habitat. The broad success of ants would still be true, but the claim that no ant species is threatened could be false.
What we’re looking for
Notice the change in the subject: first ants collectively, then every individual species. That's what the flaw answer needs to capture. The direction matters. We aren't starting with one successful species and projecting its success onto all ants. We're starting with the success of the larger group and projecting it onto every species within it.
Working the answers
- A
The problem doesn't turn on whether the two named locations are themselves isolated. Ants collectively could occupy a huge range, just as the premise says, while a particular species occupied only a small part of it. Settling the geography of the endpoints wouldn't establish the status of every species.
- B
The argument says insects are among the successful classes, with ants especially successful. It doesn't need to assume that ants are unlike most other insects. A comparison with other insects also wouldn't settle whether a particular ant species is threatened.
- C
The author doesn't need widespread distribution to be the only possible protection against becoming threatened. Perhaps some narrowly distributed animals are safe too. The problem is already present when the author transfers the broad group's success to each species, regardless of what other routes to safety exist.
- D
This runs in the other direction: from the parts to the whole. For example, it would treat the success of the individual species as establishing the success of the group made from them. Our evidence starts with ants collectively, not with a separate finding about each species. Don't let the familiar words “whole” and “elements” hide that reversal.
- ECorrect
The whole is ants as a group; its constituent elements are the different species of ant. The argument takes the group's widespread success as establishing that each species is safe. But a country can cover many climates without every state covering all those climates. Likewise, ants can occupy a huge range without each species doing so. The collective description doesn't establish the individual descriptions the conclusion needs.
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