Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that galanin makes rats crave fatty foods. Why? Because an experiment showed a correlation: rats who preferred fatty foods also had higher galanin concentrations in their brains.
Notable Assumptions
The author assumes the correlation results from one particular causation: that lots of brain galanin causes rats to crave fatty foods. This means assuming there’s no other cause for that correlation, such as the reverse causation: that eating fatty foods causes galanin to build up in rats’ brains.
A
The craving for fatty foods does not invariably result in a rat’s choosing those foods over lean foods.
This doesn’t affect the argument. Rats could have “consistently” chosen fatty food without choosing it every single time.
B
The brains of the rats that consistently chose to eat fatty foods did not contain significantly more fat than did the brains of rats that consistently chose lean foods.
This is irrelevant. The author makes no claim about fat inside the rats’ brains—only the fat in their food and the galanin in their brains.
C
The chemical components of galanin are present in both fatty foods and lean foods.
This doesn’t mean the fatty and lean diets contained similar amounts of galanin. This is fully compatible with the reverse causation: the rats who preferred fatty foods simply consumed more galanin in their diets.
D
The rats that preferred fatty foods had the higher concentrations of galanin in their brains before they were offered fatty foods.
This strengthens the argument by casting doubt on an alternative explanation. It makes the reverse causation—that rats had lots of galanin in their brains because of their high fat intake—less likely.
E
Rats that metabolize fat less efficiently than do other rats develop high concentrations of galanin in their brains.
This detail is compatible with the conclusion, but it doesn’t strengthen the argument. It’s just as compatible with the reverse causation: rats who metabolize fat less efficiently crave fattier foods, and that higher fat consumption causes galanin to build up in their brains.
Summarize Argument: Phenomenon-Hypothesis
The author concludes that to be safe from attack, people should stay home whenever possible. Why? Because news media cover more violent crime than they used to, meaning violent crime has increased dramatically.
Notable Assumptions
The author assumes media cover more violent crime because that crime is much more prevalent, and not for any other reason. In addition, he assumes people are less likely to be victims of violent crime when they stay at home.
A
Newspapers and televised news programs have more comprehensive coverage of violent crime than newspapers did in the old days.
This challenges the assumption that violent crime receives more coverage because it’s out of control. Since media today cover crime more comprehensively, an increase in coverage does not necessarily mean an increase in crime.
B
National data show that violent crime is out of control everywhere, not just in the author’s city.
This expands the scope of the conclusion, but provides no reason to question it. It implies people should stay home across the entire country, not just in the author’s city.
C
Police records show that people experience more violent crimes in their own neighborhoods than they do outside their neighborhoods.
This doesn’t say people are more likely to experience violent crime when they are at home. The author recommends people stick to their homes, not stick to their own neighborhoods when they go out.
D
Murder comprised a larger proportion of violent crimes in the old days than it does today.
This doesn’t say murder rates have decreased. It’s possible other types of violent crime have simply increased more than the murder rate.
E
News magazines play a more important role today in informing the public about crime than they did in the old days.
This doesn’t say newspapers and televised news over-report violent crime. News magazines may report the same amount of violent crime, even if that reporting is more important than it used to be.
Summarize Argument: Phenomenon-Hypothesis
The researchers hypothesize that most marmosets become left-handed because they imitate their parents as babies. Why? Because infant marmosets are known to imitate frequently.
Notable Assumptions
The researchers assume there’s no alternative or additional explanation accounting for the prevalence of left-handedness among marmosets. In particular, they assume baby marmosets tend to imitate their parents, and that genetic factors don’t determine a marmoset’s handedness.
A
A study conducted on adult marmosets revealed that many were right-handed.
This doesn’t affect the researchers’ argument. It’s stated only that “[s]ignificantly more” marmosets are left-handed than right-handed, which is compatible with the existence of many right-handed marmosets, provided there are also lots of left-handed marmosets out there.
B
Right-handed marmosets virtually all have at least one sibling who is left-handed.
This weakens the researchers’ argument. It implies left-handed and right-handed marmosets are frequently raised by the same parents, making it less likely that marmosets tend to acquire the same handedness as their parents.
C
According to the study, 33 percent of marmosets are ambidextrous, showing equal facility using either their left hand or their right hand.
This doesn’t affect the researchers’ argument. It doesn’t change the relative prevalence of left-handed marmosets, nor does it imply the researchers are basing their hypothesis on faulty evidence.
D
Ninety percent of humans are right-handed, but those who are left-handed are likely to have at least one left-handed parent.
This implies humans tend to acquire their handedness from their parents, not that humans—or marmosets—acquire their handedness through imitation. There are many reasons, besides their tendency to imitate, why marmosets might, unlike humans, tend to be left-handed.
E
Marmosets raised in captivity with right-handed adult marmosets to whom they are not related are more likely to be right-handed than left-handed.
This supports the researchers’ hypothesis that handedness is developed through imitation, rather than solely genetic or environmental factors. It implies baby marmosets tend to acquire their handedness from other, nearby marmosets—not just from genetic relatives.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that Henry was popular because it followed That’s Life and not because people actually liked it. This is evident in the fact Henry was relatively unpopular before it was scheduled to follow That’s Life, and unpopular again once it was moved to a different time spot.
Notable Assumptions
The author assumes that Henry itself didn’t change in a way that attracted a larger audience (i.e. better writing, better acting, more compelling storylines) after it was moved to follow That’s Life. The author also assumes that Tuesdays aren’t a particularly strong day for TV shows in general. If this were the case, then Henry’s popularity could be explained by the day of the week it was scheduled on, rather than by the show that preceded it.
A
Henry has been on the air for three years, but That’s Life has been on the air for only two years.
We don’t care how long That’s Life had been on air for. We care about Henry’s popularity over the years.
B
The show that replaced Henry on Tuesdays has persistently had a low number of viewers in the Tuesday time slot.
This weakens the claim that Henry was popular because of its Tuesday time slot. We’re looking to do the opposite.
C
The show that now follows That’s Life on Tuesdays has double the number of viewers it had before being moved.
Tuesday after That’s Life is a great time slot for shows. Henry improved its numbers, as did this other show. This strengthens the claim that the time slot, rather than the show, is what matters ratings-wise.
D
After its recent move to Wednesday, Henry was aired at the same time as the second most popular show on television.
This might explain why Henry did poorly on Wednesday. But we have no idea if a similar phenomenon was happening when Henry was aired on Tuesday, so we can’t draw any conclusions from this.
E
That’s Life was not widely watched during the first year it was aired.
We don’t care about That’s Life. We know it ended up being popular.