Meteorologist: Heavy downpours are likely to become more frequent if Earth’s atmosphere becomes significantly warmer. A warm atmosphere heats the oceans, leading to faster evaporation, and the resulting water vapor forms rain clouds more quickly. A warmer atmosphere also holds more moisture, resulting in larger clouds. In general, as water vapor in larger clouds condenses, heavier downpours are more likely to result.

Summarize Argument
The author concludes that if Earth’s atmosphere becomes significantly warmer, heavy downpours are likely to become more frequent. This is supported by a causal chain. A warm atmosphere leads to faster evaporation, which leads to rain clouds forming more quickly. A warm atmosphere also leads to more moisture in the atmosphere, which makes clouds larger. The larger, more quickly forming rain clouds result in heavier downpours. This is how heavy downpours are more likely if the atmosphere gets warmer.

Identify Argument Part
The referenced text is offered as support for the conclusion. It’s part of the causal chain that shows how a warmer atmosphere can lead to more frequent heavy downpours.

A
It is the only conclusion in the argument.
The referenced text is not a conclusion. It’s a premise offered to support the conclusion.
B
It is the conclusion of the argument as a whole but is not the only explicitly stated conclusion in the argument.
The referenced text is not a conclusion. It’s a premise offered to support the conclusion.
C
It is a statement that the argument is intended to support but is not the conclusion of the argument as a whole.
The referenced text is not supported by any other statement. It’s a premise offered to support the conclusion.
D
It is used to support the only conclusion in the argument.
This accurately describes the role of the referenced text. It is part of the causal chain that is offered to support the conclusion in the first sentence.
E
It provides a causal explanation of the phenomenon described by the conclusion of the argument as a whole, but it is not intended to provide support for that conclusion.
The referenced text does provide support for the conclusion.

54 comments

Politician: A major social problem is children hurting other children. The results of a recent experiment by psychologists establish that watching violent films is at least partly responsible for this aggressive behavior. The psychologists conducted an experiment in which one group of children watched a film of people punching Bobo the Clown dolls. A second group of children was not shown the film. Afterward, both groups of children played together in a room containing a Bobo doll. Most of the children who had seen the film punched the Bobo doll, while most of the other children did not.

Summarize Argument: Phenomenon-Hypothesis

The politician hypothesizes that watching violent films contributes to the problem of children hurting other children. He supports this by citing a study where most children who saw a film of people punching a Bobo the Clown doll later punched the doll themselves, while those who didn't watch the film didn't punch it.

Notable Assumptions

The politician assumes that punching the Bobo doll is an accurate indicator of a child's tendency to hurt other children.

He also assumes that the study is representative and that its findings can be generalized to all children.

He also assumes that watching the film is the primary or sole cause of the children's behavior, ignoring other potential factors that could contribute to their behavior.

A
Some of the children who did not punch the Bobo doll, including some who had been shown the film, chastised those who did punch the doll.

Whether some of the children in each group chastised children who punched the doll doesn’t weaken the politician’s argument, which relies on the observation that most of the children who watched the film did punch the doll.

B
The child who punched the Bobo doll the hardest and the most frequently had not been shown the film.

Even if a child who didn't watch the film punched the doll the hardest, the fact remains that most children who watched the film did punch the doll, while most who didn't watch it did not. So (B) doesn’t weaken the politician's argument.

C
The children who had been shown the film were found to be no more likely than the children who had not been shown the film to punch other children.

The politician aims to address children hurting other children. For his conclusion to hold, he must assume that children who punch the doll will also hurt other children. But if children who watch the film are no more likely to punch other children, his argument falls apart.

D
Some children who had not been shown the film imitated the behavior of those who had been shown the film and who punched the doll.

Like (B), it doesn’t matter that some of the children who didn’t watch the film later punched the doll, because the politician’s argument relies on the fact that most children who watched the film did punch the doll, while most who didn't watch it did not.

E
Many of the children who participated in the experiment had never seen a Bobo doll before the experiment.

Whether the children had seen a Bobo doll before doesn’t change how the groups reacted to the doll after watching the film or not watching film.


19 comments

Climatologists believe they know why Earth has undergone a regular sequence of ice ages beginning around 800,000 years ago. Calculations show that Earth’s orbit around the Sun has fluctuations that coincide with the ice-age cycles. The climatologists hypothesize that when the fluctuations occur, Earth passes through clouds of cosmic dust that enters the atmosphere; the cosmic dust thereby dims the Sun, resulting in an ice age. They concede, however, that though cosmic dust clouds are common, the clouds would have to be particularly dense in order to have this effect.

Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that the regular sequence of ice ages Earth has experienced since 800,000 years ago are caused by Earth’s passing through clouds of cosmic dust. According to this theory, the cosmic dust enters Earth’s atmosphere, which dims the sun, causing an ice age.

Notable Assumptions
The author assumes there’s no other explanation for what causes Earth’s regular sequence of ice ages. The author assumes that the occurrence of ice ages is correlated with Earth’s passage through clouds of cosmic dust.

A
Earth did not pass through clouds of cosmic dust earlier than 800,000 years ago.
This strengthens by defending the argument from the possibility that passage through cosmic dust occcurred before the ice ages starting to occur.
B
Two large asteroids collided 800,000 years ago, producing a tremendous amount of dense cosmic dust that continues to orbit the Sun.
This helps establish that the dense cosmic dust the author’s hypothesis requires actually exists and correlates with the beginning of the ice ages.
C
Earth’s average temperature drops slightly shortly after volcanic eruptions spew large amounts of dust into Earth’s atmosphere.
This strengthens by showing that dust in Earth’s atmosphere can reduce Earth’s average temperature. This makes the author’s theory about dust causing ice ages more plausible. Although (C) is about volcanic dust, it still shows that dust in atmosphere can cool the Earth.
D
Large bits of cosmic rock periodically enter Earth’s atmosphere, raising large amounts of dust from Earth’s surface.
(D) tells us that cosmic rock periodically enters the atmosphere. But does the Earth get colder after this happens? We don’t know. Do these periodic entries of cosmic rock coincide with Earth’s ice ages? We don’t know. (D) has no impact.
E
Rare trace elements known to be prevalent in cosmic debris have been discovered in layers of sediment whose ages correspond very closely to the occurrence of ice ages.
This provides evidence of a correlation between cosmic debris and the occurrence of ice ages.

65 comments