- PowerScore Staff
- Posts: 8950
- Joined: Feb 02, 2011
- Sat Jul 01, 2017 8:26 am
#36673
Complete Question Explanation
Assumption. The correct answer choice is (E)
This paleontologist’s discussion surrounds “plesiosauromorphs.” Hopefully you didn’t bother
pronouncing that one—as long as you can just recognize the word refers to a large animal from the
dinosaur era, your energy and focus are probably better spent elsewhere. Most believe that these big
reptiles (we’ll refer to them as “plesi-reptiles”) hunted by hiding and ambushing their prey, but this
author believes that they probably hunted their prey by long-distance chase. This conclusion is based
on a single premise, presented in the final sentence of the stimulus: these plesi-reptiles had long, thin
fins, much like the wings of birds that are specialized for long flight. This simple argument can be
diagrammed as follows:
same way that birds use their similarly shaped wings—for the purpose of long distance travel, and
that this was a strategy they used for hunting.
The stimulus is followed by an Assumption question, so the correct answer choice will probably
reflect one of the Supporter assumptions discussed above.
Answer choice (A): The argument does not depend on the assumption that birds and reptiles share
many common features, but rather that one common feature affects the two in a similar fashion.
To confirm that this answer choice is incorrect, we can apply the Assumption Negation technique,
knowing that the right answer choice, when logically negated, will weaken the author’s argument.
The negated form of this answer choice would be something like “Birds and reptiles don’t share
many physical features based on common ancestry.” This would not weaken the author’s argument,
which deals with only one common physical feature of birds and reptiles—the wings and fins,
respectively.
Note that you do not need to negate every answer choice, but we shall do so in the analysis of each
answer choice in order to explain each answer as fully as possible.
Answer choice (B): This stimulus deals exclusively with this one type of reptile, so there is no need
for the author to presume that it was the only reptile of the time that had long, thin fins. Negating this
choice yields the following:
conclusion, so this cannot be the correct answer choice.
Answer choice (C): This choice basically says that something the size of the plesi-reptile could only
have survived by hunting over long distances. This assumption is not required by the paleontologist’s conclusion. If this stimulus had instead been followed by a Justify the Conclusion question stem, this
choice would have worked, since it would justify the author’s conclusion that the reptile probably
hunted prey over long distances. However, since this assumption is not required by the argument, it
is not the right answer to this Assumption question.
To confirm that this is not the correct answer choice, we can again apply the Assumption Negation
technique. Even if there had been other ways for the plesi-reptile to survive, this would not hurt the
author’s conclusion, which is based not on the animal’s needs but on a feature similar to one of long
distance flight birds.
Answer choice (D): The author’s argument does not require presuming anything about “most marine
animals that chase prey over long distances,” because this is not the basis of the author’s conclusion.
To confirm that this is not the correct answer choice, we can again apply the Assumption Negation
technique: even if most long-distance-prey-chasing marine animals are not specialized for long
distance swimming, this would not weaken the paleontologist’s argument, which deals only with one
particular reptile.
Answer choice (E): This is the correct answer choice. Since the conclusion is based on the
similarity between the plesi-reptile’s fins and long distance birds’ wings, the paleontologist must
assume that there is some significant similarity between their uses.
Again, since this is an Assumption question, the correct answer can always be confirmed with the
Assumption Negation technique: the right answer choice will provide an assumption which, when
negated, weakens the conclusion in the stimulus. If we logically negate answer choice (E), the result
is, “the shape of a marine animal’s fin does not affect the way the animal swims in the same way
that the shape of a bird’s wing affects the way a bird flies.” This would defeat the paleontologist’s
argument, which is based on the presuming that this similarity exists.
Assumption. The correct answer choice is (E)
This paleontologist’s discussion surrounds “plesiosauromorphs.” Hopefully you didn’t bother
pronouncing that one—as long as you can just recognize the word refers to a large animal from the
dinosaur era, your energy and focus are probably better spent elsewhere. Most believe that these big
reptiles (we’ll refer to them as “plesi-reptiles”) hunted by hiding and ambushing their prey, but this
author believes that they probably hunted their prey by long-distance chase. This conclusion is based
on a single premise, presented in the final sentence of the stimulus: these plesi-reptiles had long, thin
fins, much like the wings of birds that are specialized for long flight. This simple argument can be
diagrammed as follows:
- Premise: Plesi-reptiles had fins that resembled long distance birds’ wings.
Conclusion: Plesi-reptiles must have hunted by chasing their prey over long distances.
same way that birds use their similarly shaped wings—for the purpose of long distance travel, and
that this was a strategy they used for hunting.
The stimulus is followed by an Assumption question, so the correct answer choice will probably
reflect one of the Supporter assumptions discussed above.
Answer choice (A): The argument does not depend on the assumption that birds and reptiles share
many common features, but rather that one common feature affects the two in a similar fashion.
To confirm that this answer choice is incorrect, we can apply the Assumption Negation technique,
knowing that the right answer choice, when logically negated, will weaken the author’s argument.
The negated form of this answer choice would be something like “Birds and reptiles don’t share
many physical features based on common ancestry.” This would not weaken the author’s argument,
which deals with only one common physical feature of birds and reptiles—the wings and fins,
respectively.
Note that you do not need to negate every answer choice, but we shall do so in the analysis of each
answer choice in order to explain each answer as fully as possible.
Answer choice (B): This stimulus deals exclusively with this one type of reptile, so there is no need
for the author to presume that it was the only reptile of the time that had long, thin fins. Negating this
choice yields the following:
- During the age of dinosaurs, plesiosauromorphs were NOT the only marine reptiles that had
long, thin fins.
conclusion, so this cannot be the correct answer choice.
Answer choice (C): This choice basically says that something the size of the plesi-reptile could only
have survived by hunting over long distances. This assumption is not required by the paleontologist’s conclusion. If this stimulus had instead been followed by a Justify the Conclusion question stem, this
choice would have worked, since it would justify the author’s conclusion that the reptile probably
hunted prey over long distances. However, since this assumption is not required by the argument, it
is not the right answer to this Assumption question.
To confirm that this is not the correct answer choice, we can again apply the Assumption Negation
technique. Even if there had been other ways for the plesi-reptile to survive, this would not hurt the
author’s conclusion, which is based not on the animal’s needs but on a feature similar to one of long
distance flight birds.
Answer choice (D): The author’s argument does not require presuming anything about “most marine
animals that chase prey over long distances,” because this is not the basis of the author’s conclusion.
To confirm that this is not the correct answer choice, we can again apply the Assumption Negation
technique: even if most long-distance-prey-chasing marine animals are not specialized for long
distance swimming, this would not weaken the paleontologist’s argument, which deals only with one
particular reptile.
Answer choice (E): This is the correct answer choice. Since the conclusion is based on the
similarity between the plesi-reptile’s fins and long distance birds’ wings, the paleontologist must
assume that there is some significant similarity between their uses.
Again, since this is an Assumption question, the correct answer can always be confirmed with the
Assumption Negation technique: the right answer choice will provide an assumption which, when
negated, weakens the conclusion in the stimulus. If we logically negate answer choice (E), the result
is, “the shape of a marine animal’s fin does not affect the way the animal swims in the same way
that the shape of a bird’s wing affects the way a bird flies.” This would defeat the paleontologist’s
argument, which is based on the presuming that this similarity exists.