Criminologist: According to a countrywide tabulation of all crimes reported to local police departments, the incidence of crime per 100,000 people has risen substantially over the last 20 years. However, a series of independent surveys of randomly selected citizens of the country gives the impression that the total number of crimes was less in recent years than it was 20 years ago.
"Surprising" Phenomenon
Crime rates are up, but people surveyed believe the total number of crimes are down.
Objective
The right answer will be a hypothesis that explains the difference between the statistic about crime rates and public perception of total crime. That difference must account for either an actual decrease in the number of total crimes due to a reduced population, for the public simply being wrong about crime in the country, or for some mitigating factor around crime reporting.
A
Not all of the citizens selected for the series of independent surveys had been the victims of crime.
This just means that at least one person surveyed wasn’t a crime victim. It explains nothing about why public perception about total crime differs from crime rate statistics.
B
Most crimes committed in the country are not reported to local police departments.
If most crimes committed aren’t reported, then the crime rate statistics would undersell total crime. But people surveyed seem to think that crime has gone down. This doesn’t explain that discrepancy.
C
The total annual number of crimes committed in the country has risen over the past 20 years but has fallen in proportion to the country’s growing population.
This seems to contradict official statistics. Crime rates are up, whereas this suggests that crime rates are down.
D
In the series of independent surveys, many of the respondents did not accurately describe the crimes to which they had fallen victim.
The respondents weren’t necessarily victims of crimes. And of those who did, we don’t care how accurately they described being victims of crimes.
E
Of crimes committed in the country, a much greater proportion have been reported to local police departments in recent years than were reported 20 years ago.
Crime rates are up because people are reporting crimes to the police. However, it could still be true that the total number of crimes has fallen during that same time period. This explains why public surveys and official crime rate statistics give incongruous results.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that the Neanderthals who had used a particular campsite had inhabited the campsite year-round and were not nomadic. This is based on the the fact that discarded gazelle teeth at the campsite showed that the gazelles were hunted throughout the year. This was unlike what was found in a nearby campsite of a nomadic Cro-Magnon group, which contained teeth from gazelles killed only during a single season.
Notable Assumptions
The author assumes that the only explanation for the presence of discarded gazelle teeth from gazelles hunted throughout the year is that the Neanderthals lived at the campsite all year.
A
Neanderthals hunted a wide variety of both migratory and nonmigratory animals.
If (A) does anything, it might support the theory that the Neanderthals stayed at the campsite by showing that Neanderthals did not need to follow a migratory animals around for food.
B
Cro-Magnons and Neanderthals sometimes exchanged tools.
An exchange of tools has no clear relationship to whether Neanderthals were nomadic or stayed in the same place. Perhaps the exchange of tools happened when the Cro-Magnons happened to be in the area around the Neanderthals.
C
Neanderthals saved gazelle teeth for use in religious rituals and later discarded them.
This provides another explanation for the presence of discarded gazelle teeth that showed gazelles were hunted throughout the year. The Neanderthals may have moved around, hunted gazelles as they moved, and then dumped the teeth they collected at one campsite.
D
Cro-Magnons usually followed the migrations of the animals they hunted.
This suggests that Cro-Magnons were nomadic. But Neanderthals are a different group and we have reason to think Neanderthals behaved differently from Cro-Magnons (the difference in gazelle teeth at each campsite).
E
Gazelles inhabited the area around the campsites year-round.
This supports the author’s theory by showing that Neanderthals could have stayed at the site year-round and hunted gazelles year-round. This eliminates the possibility that gazelles were in the area for only a short time each year.
Miriam: A moral theory, like an overcoat, can be quite useful even if it is not useful in every possible situation. Being useful in a wide variety of common circumstances is all we need from a moral theory.
Speaker 1 Summary
Laurel concludes that modern moral theories have to be abandoned or reworked, because they don’t provide guidance in extreme. Extreme cases are the times when people most need guidance.
Speaker 2 Summary
Miriam asserts that moral theories can still be useful, even if not useful in all situations. They serve their purpose if they’re useful in a wide variety of common situations.
Objective
We’re looking for a point of disagreement. They disagree about whether moral theories’ failure to help in extreme situations justifies abandoning or reworking them. Laurel think it does, but Miriam thinks it doesn’t.
A
it is preferable to develop a moral theory that provides solutions to all the moral dilemmas that could arise
Miriam doesn’t have an opinion. She describes what we need from a moral theory, but doesn’t describe whether it’d be better for a moral theory to provide solutions to all problems that could arise.
B
people abandoned earlier moral theories when they encountered dilemmas that those theories did not adequately address
Neither speaker has an opinion. They don’t discuss whether people abandoned earlier theories or why people abandoned earlier theories.
C
a moral theory’s adequacy depends on its ability to provide guidance in extreme cases
This is a point of disagreement. Laurel thinks a moral theory’s adequacy does depend on its ability to guide in extreme cases. But Miriam believes it doesn’t. A moral theory just needs to provide guidance in the most common situations.
D
just as people need different overcoats in different climates, so too do they need different moral theories on different occasions
Neither speaker has an opinion. They don’t discuss whether people ever need different moral theories during different situations.
E
a moral theory developed in the light of extreme cases is unlikely to provide adequate guidance in more usual cases
Neither speaker has an opinion. They don’t discuss whether moral theories that apply in extreme cases are unlikely to provide guidance in more typical cases.
Summarize Argument: Causal Explanation
The scientist confidently claims that the ice ages were caused by widespread, unusually rich growth of vegetation. His reasoning is that vegetation converts oxygen into CO2. CO2 retains heat. Excess vegetation caused a reduction in CO2, causing the earth to cool due to a lack of heat retention. This cooling caused the ice ages.
Identify Conclusion
The conclusion is the scientist’s explanation for the ice ages: “There is little doubt that the ice ages were caused by the unusually rich growth of vegetation worldwide.”
A
Excessive growth of vegetation worldwide could have caused one or more ice ages by depleting the carbon dioxide in the atmosphere.
This is too weak to match the conclusion. The scientist claims that the excessive growth of vegetation almost definitely caused all of the ice ages.
B
If the carbon dioxide in the atmosphere is depleted, the earth cools significantly, thereby causing an ice age.
This is part of the causal explanation that shows how excessive vegetation would cause an ice age.
C
An excessive growth of vegetation causes the carbon dioxide in the atmosphere to be depleted.
This is also part of the chained explanation showing the process of how excessive vegetation would cause an ice age.
D
If unusually rich growth of vegetation caused the ice ages, it undoubtedly did so by depleting the carbon dioxide in the atmosphere.
This “if” statement does not match the conclusion. The author definitively states that the phenomenon did happen, and it happened by this process.
E
Unusually rich growth of vegetation worldwide was almost certainly the cause of the ice ages.
This accurately matches the strength and content of the conclusion. “Almost certainly” matches the author’s “there is little doubt” that this unusual vegetation growth caused the ice ages.
Summarize Argument: Phenomenon-Hypothesis
The author concludes that exercise can increase life span. This is because the subjects in a study who exercised were less likely to die during the study than the subjects who didn’t exercise.
Notable Assumptions
The author assumes that there was no prior correlation between people who exercised and were in good health, or people who didn’t exercise and were in poor health. If people on the verge of dying didn’t exercise given their health condition, then the study wouldn’t indicate anything about the effects of exercise.
A
The subjects who did not exercise regularly during the study tended to have diets that were more unhealthy.
This weakens the author’s argument by bringing in a third factor: diet. Perhaps the people who didn’t die were saved by their diets rather than by exercise.
B
The subjects who did not exercise regularly during the study tended to blame their lack of exercise on a lack of time.
This doesn’t do much. Perhaps those people had little time because they were stressed about other things, and the stress ended up damaging their health.
C
A large number of the deaths recorded were attributable to preexisting conditions or illnesses.
This severely damages the author’s argument. People died because of their preexisting conditions rather than their lack of exercise.
D
Whether or not a given subject was to exercise during the study was determined by the researchers on a random basis.
There was no connection between prior health and exercise. This defends against the obvious weakener that only already-healthy people were exercising.
E
A person who exercises regularly is probably doing so out of concern for his or her own health.
We don’t care what motivated the participants to exercise.