- Mon May 02, 2016 1:35 pm
#23759
Complete Question Explanation
Assumption. The correct answer choice is (B)
The ornithologist states that the curvature of Archaeopteryx’s claws would enable the creature to perch in trees, and concludes that the creature was a tree-dwelling animal.
The paleontologist points out that chickens can perch in trees, but are not tree dwelling, and concludes that the ability to perch in trees is not good evidence that Archaeopteryx was a tree-dwelling animal.
The ornithologist’s argument is essentially a Mistaken Reversal of a commonsense assumption. It makes good sense to suppose that the ability to perch in trees is probably necessary for an animal to be tree-dwelling. However, that does not mean that the ability to perch in trees is sufficient for an animal to be tree-dwelling.
In any case, you are asked to identify a required assumption, so you should focus on the fact that simply because the Archaeopteryx might have perched in trees, the ornithologist concludes that it definitely did so.
Answer choice (A): The ornithologist’s argument concerns only whether the Archaeopteryx was tree-dwelling, not whether it is the ancestor of modern tree-dwelling birds. This off-topic response is incorrect.
Answer choice (B): This is the correct answer choice. The ornithologist concludes that the Archaeopteryx was tree-dwelling, which by any rational standard would involve perching in trees and therefore the use of the creature’s claws. The negation test shows that if the Archaeopteryx did not make use of the curvature of its claws, it would not have perched in trees, so the creature would not be tree-dwelling. That means that this assumption is required by the argument.
Answer choice (C): The fact that all tree-dwelling birds have curved claws does not support the conclusion that all birds with curved claws are tree-dwelling. This response is the commonsense assumption that the ornithologist has mistakenly reversed, and you should avoid making the same error. This choice is wrong, because the ornithologist assumes the Mistaken Reversal of this choice rather than this choice itself.
Answer choice (D): Even if the Archaeopteryx was the earliest birdlike creature, that would not help establish that the Archaeopteryx perched in trees. And from the fact that birds perch in trees today, it is easy to see that having birdlike predecessors would not damage the possibility that a creature perches in trees. This choice is wrong, because it offers no support and, in negation, is still irrelevant.
Answer choice (E): The ornithologist is attempting to show that the Archaeopteryx was a tree-dwelling creature, not that there is only one way to show that the creature was tree-dwelling. In any case, the possibility that there is only one way to argue for a conclusion does not support that the conclusion should be argued for. This choice is incorrect.
Assumption. The correct answer choice is (B)
The ornithologist states that the curvature of Archaeopteryx’s claws would enable the creature to perch in trees, and concludes that the creature was a tree-dwelling animal.
The paleontologist points out that chickens can perch in trees, but are not tree dwelling, and concludes that the ability to perch in trees is not good evidence that Archaeopteryx was a tree-dwelling animal.
The ornithologist’s argument is essentially a Mistaken Reversal of a commonsense assumption. It makes good sense to suppose that the ability to perch in trees is probably necessary for an animal to be tree-dwelling. However, that does not mean that the ability to perch in trees is sufficient for an animal to be tree-dwelling.
In any case, you are asked to identify a required assumption, so you should focus on the fact that simply because the Archaeopteryx might have perched in trees, the ornithologist concludes that it definitely did so.
Answer choice (A): The ornithologist’s argument concerns only whether the Archaeopteryx was tree-dwelling, not whether it is the ancestor of modern tree-dwelling birds. This off-topic response is incorrect.
Answer choice (B): This is the correct answer choice. The ornithologist concludes that the Archaeopteryx was tree-dwelling, which by any rational standard would involve perching in trees and therefore the use of the creature’s claws. The negation test shows that if the Archaeopteryx did not make use of the curvature of its claws, it would not have perched in trees, so the creature would not be tree-dwelling. That means that this assumption is required by the argument.
Answer choice (C): The fact that all tree-dwelling birds have curved claws does not support the conclusion that all birds with curved claws are tree-dwelling. This response is the commonsense assumption that the ornithologist has mistakenly reversed, and you should avoid making the same error. This choice is wrong, because the ornithologist assumes the Mistaken Reversal of this choice rather than this choice itself.
Answer choice (D): Even if the Archaeopteryx was the earliest birdlike creature, that would not help establish that the Archaeopteryx perched in trees. And from the fact that birds perch in trees today, it is easy to see that having birdlike predecessors would not damage the possibility that a creature perches in trees. This choice is wrong, because it offers no support and, in negation, is still irrelevant.
Answer choice (E): The ornithologist is attempting to show that the Archaeopteryx was a tree-dwelling creature, not that there is only one way to show that the creature was tree-dwelling. In any case, the possibility that there is only one way to argue for a conclusion does not support that the conclusion should be argued for. This choice is incorrect.