Until recently it was widely believed that only a limited number of species could reproduce through parthenogenesis, reproduction by a female alone. But lately, as interest in the topic has increased, parthenogenesis has been found in a variety of unexpected cases, including sharks and Komodo dragons. So the number of species that can reproduce through parthenogenesis must be increasing.
Summarize Argument
The author concludes that the number of species that can reproduce through parthenogenesis must be increasing. She supports this by noting that, as interest in the topic has grown, parthenogenesis has been discovered in more unexpected species.
Identify and Describe Flaw
The author assumes that parthenogenesis is on the rise just because more cases have been discovered. She overlooks the possibility that these species may have always reproduced this way, and humans are just now aware of it. In other words, the lack of interest and knowledge about parthenogenesis in the past doesn't mean that it didn't occur before.
A
equates mere interest in a subject with real understanding of that subject
The author never assumes that people’s increased interest in parthenogenesis means that they really understand it. She just claims that more cases of parthenogenesis have been found since interest in it has increased.
B
takes for granted that because one thing follows another, the one must have been caused by the other
This is the cookie-cutter flaw of assuming that correlation proves causation. The author doesn’t draw a causal conclusion at all. She concludes that the number of species that use parthenogenesis is increasing, but she doesn’t say that increased interest caused this increase.
C
takes ignorance of the occurrence of something as conclusive evidence that it did not occur
The author assumes that humans’ ignorance of certain species’ ability to reproduce through parthenogenesis is evidence that they could not reproduce this way before. But it’s more likely that these species always reproduced this way, and humans are just now aware of it.
D
overlooks a crucial difference between two situations that the argument presents as being similar
This is describing a flawed analogy. The author doesn’t make this mistake. She doesn’t present two situations as being similar in the first place. Instead, she assumes that parthenogenesis is on the rise just because more cases have been discovered.
E
presumes that because research is new it is, on that basis alone, better than older research
The author never assumes that new research is better than old research. She points out that humans are aware of more cases of parthenogenesis than they were in the past. But her flaw is in the assumption that this increased knowledge means that parthenogenesis is on the rise.
A
Unlike Earth, Jupiter’s atmosphere is warmed by the planet’s internal heat source.
B
Jupiter’s atmosphere is composed of several gases that are found in Earth’s atmosphere only in trace amounts.
C
Gaseous planets such as Jupiter sometimes have stronger winds than do rocky planets such as Earth.
D
There are more planets that have winds stronger than Earth’s than there are planets that have winds weaker than Earth’s.
E
Planets even farther from the Sun than Jupiter are known to have atmospheric winds.
It’s possible that people expected to benefit from their actions, even though they didn’t benefit. In this case, the author can’t conclude that rational-choice theory is incorrect.