PrepTest 137, Section 3, Question 19
Ecologist: One theory attributes the ability of sea(61 more words not shown)
The reasoning in the ecologist's(7 more words not shown)
- Apresumes, without providing(10 more words not shown)
- Bdraws a conclusion(13 more words not shown)
- Ctreats a condition(15 more words not shown)
- Dinfers, from the(23 more words not shown)
- Edraws a conclusion(12 more words not shown)
Reading the argument
Eating a pellet isn't necessarily like eating a sea butterfly.
What if a predator once ate a sea butterfly, became sick, and learned to avoid that animal? It might still eat an unfamiliar food pellet containing the same chemical because it doesn't recognize the pellet as something associated with getting sick. In that hypothetical case, the chemical helps explain avoidance of the animal even though the predator eats the pellet.
I also wouldn't assume appearance and chemistry have to be competing explanations. The animal's appearance might help the predator recognize the source of an unpleasant chemical experience. But let's be careful about the argument's actual conclusion: it rejects the chemical explanation. It doesn't explicitly announce that appearance is the sole explanation.
What we’re looking for
For the flaw question, my initial concern is the jump from the pellet experiment to behavior toward the animal. We need to check what the experiment actually rules out. Predators eating these pellets may leave other ways for the compounds to protect sea butterflies.
Working the answers
- A
The two theories could work together, but the author doesn't argue that accepting one requires rejecting the other. The stated reason for rejecting the chemical explanation is the pellet experiment. A describes an assumption we might have expected the author to make, rather than the inference actually offered.
- B
The evidence is an experiment adding compounds to pellets and observing whether predators eat them. This isn't merely a statistical association used to declare that one thing causes another. The problem is what this particular experimental setup can establish about the compounds' protective effect.
- C
We aren't given a condition established as enough for avoiding predators and then told that it is required. The author instead rejects a proposed protective cause based on test results. C doesn't map the reasoning about what the compounds do individually and in the animal.
- DCorrect
Here's another limitation of the experiment: each pellet contained only one compound. Suppose predators eat a pellet containing X, one containing Y, and one containing Z. Have we shown that they'll eat a pellet containing X, Y, and Z together? No. The combination might have an effect the individual compounds lack.
That differs from my initial learned-avoidance example, but it directly exposes the gap. The experiment tested the members of the chemical set separately; the conclusion dismisses the set's protective effect altogether. Sea butterflies producing the compounds together could still be protected by that combination.
- E
The conclusion doesn't simply repeat the observation. The observation says predators ate pellets containing individual compounds. The conclusion makes the broader claim that the compounds aren't responsible for avoiding predation. The problem is that broader step, not a circular restatement of something already assumed.
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