Several Tyrannosaurus rex skeletons found in North America contain tooth marks that only a large carnivore could have made. At the time T. rex lived, it was the only large carnivore in North America. The tooth marks could have resulted only from combat or feeding. But such tooth marks would have been almost impossible to inflict on the skeleton of a live animal.
Summary
There are several T. Rex skeletons found in North America with tooth marks that could only have been made by a large carnivore. T. Rex were the only large carnivores in North America when they lived. The tooth marks could only have resulted from combat or feeding. These tooth marks would have been impossible to inflict on the skeleton of a live animal.
Strongly Supported Conclusions
The tooth marks on the T. Rex skeletons are likely a product of other T. Rex’s feeding on T. Rex bodies.
A
T. rex regularly engaged in combat with smaller carnivores.
This is unsupported because we don’t have information about tooth marks being found on the skeletons of other carnivores or any other evidence of such combat.
B
At the time T. rex lived, it was common for carnivores to feed on other carnivores.
This is unsupported because even though T. Rex appears to have fed on other T. Rex, we don’t know that this was common for other carnivores.
C
T. rex sometimes engaged in cannibalism.
This is strongly supported because we know that the marks on the skeletons could only have come from other T. Rex’s, and they could only have been made during feeding on an already dead animal.
D
T. rex sometimes engaged in intraspecies combat.
This is unsupported because the marks on the skeletons could only have been made on already dead animals, which precludes the marks being made during combat.
E
At the time T. rex lived, there were large carnivores on continents other than North America.
This is unsupported because we don’t know anything about the distribution of carnivores across other continents. The stimulus is confined to discussing North America.
Summary
The author concludes that human emotions are not physical phenomena. Why? Because science, including physics, chemistry, and neurophysiology, can’t adequately explain emotions.
Missing Connection
Does the fact emotions can’t be explained by science prove that emotions are not physical? Not necessarily; we don’t know what’s required to be considered a physical phenomenon. To make the argument valid, we want to prove that if something can’t be explained by science, then it’s not a physical phenomenon. Or in other words, in order to be a physical phenomenon, it must be explainable by science.
A
Whatever is not a physical phenomenon cannot be explained by science.
(A) tells us that if something isn’t physical, then it can’t be explained by science. This is the reversed form of what we’re looking for. We want to know that if something can’t be explained by science, then it’s not physical.
B
Nothing that can be felt by only one subject can be studied scientifically.
(B) doesn’t establish anything about what’s not considered physical. Since neither this answer nor the premises establish what’s not considered physical, it can’t make the argument valid.
C
Physics, chemistry, and neurophysiology have similar explanatory frameworks.
(C) doesn’t establish anything about what’s not considered physical. Since neither this answer nor the premises establish what’s not considered physical, it can’t make the argument valid.
D
Whatever is not a physical phenomenon is an emotional one.
(D) says that if something is not physical, then it’s emotional. But we’re trying to reach the conclusion that something is not physical. Learning what happens IF we start off knowing that something is not physical doesn’t make the argument valid.
E
Every physical phenomenon can be explained by physics, chemistry, or neurophysiology.
(E) establishes that to be physical, something must be explainable by physics/chemistry/neurophysiology. We know from a premise that emotions can’t be explained by physics/chemistry/neurophysiology. So emotions aren’t physical.
Ivan: I disagree with your analysis. The country’s economy is tied to the global economy. Whatever happens to the global economy also happens here, and the global economy has slowed. Therefore, the government’s action did not cause the economy’s slowdown.
Speaker 1 Summary
Gabriella claims that the government’s recent interest rate increase has slowed the economy. How so? By encouraging people to borrow more money and spend less money. (Gabriella is making an assumption that borrowing more and spending less slows the economy.)
Speaker 2 Summary
Ivan says that the interest rate increase didn’t slow the economy. In support, Ivan explains that whatever happens to the global economy is reflected in the country’s economy. Also, the global economy has slowed. Ivan sees this as an alternative explanation for the domestic slowdown.
Objective
We’re looking for a point of disagreement. Gabriella and Ivan disagree about whether the government’s interest rate increase caused the country’s economy to slow.
A
the economic slowdown in the country has caused people to spend less
Neither speaker talks about the effect the economic slowdown may have had on people’s behavior. Gabriella claims that lower spending helped to cause the slowdown, but doesn’t mention whether the slowdown could then further lower spending.
B
the economy of the country is tied to the economies of other countries
Ivan agrees that this is the case, but Gabriella doesn’t state an opinion. Gabriella only talks about the domestic economy, and says nothing about how the international economy might be involved.
C
raising interest rates caused a significant decrease in borrowing
Gabriella disagrees that this is the case, but Ivan doesn’t express an opinion. Gabriella thinks that raising interest rates increased, not decreased, borrowing. Ivan doesn’t talk about borrowing at all.
D
raising interest rates caused the country’s economy to slow
Gabriella thinks this is true and Ivan thinks it’s false, meaning that this is the point of disagreement. Gabriella’s conclusion is that the interest rate increase caused the slowdown. Ivan says that the global economy caused the slowdown, so interest rates are irrelevant.
E
the global economy has slowed
Ivan agrees with this, but Gabriella doesn’t state an opinion. Gabriella only talks about the domestic economy, and never mentions a belief that the global economy has slowed or not.
Summarize Argument
The author claims funny jokes are difficult to remember, even though music and funny jokes both elicit emotional responses and music aids memory because of its repeated patterns.
Notable Assumptions
The author assumes there’s some difference between music and funny jokes that allows people to remember music more easily. This means assuming funny jokes either lack the repeated patterns of music or that they have some other characteristic, which music doesn’t have, that makes them difficult to remember regardless.
A
jokes, unlike music, always have content that is verbal or at least clearly symbolic
This is a difference between jokes and music, but it doesn’t explain why jokes are difficult to remember. The author says repeated patterns make something easy to remember, not that verbal or symbolic content makes something difficult to remember.
B
some successful jokes are short and pithy, whereas others are long and involved
This doesn’t say funny jokes have no repeated patterns. There’s no indication a long, involved joke can’t also have repeated patterns that make it easy to remember.
C
jokes work not by conforming to repeated patterns but by breaking them
This is a difference between jokes and music that explains why jokes are more difficult to remember. It implies funny jokes lack the adherence to repeated patterns that makes music an aid to memory.
D
for most people, certain memories elicit a strong emotional response
This suggests remembering a funny joke can produce an emotional response, but it draws no contrast between jokes and music that explains why funny jokes are usually harder to remember.
E
people can hold in short-term memory only a few chunks of unpatterned information at a time
This helps explain why repeated patterns make something easy to remember, but it draws no contrast between music and funny jokes. In particular, it doesn’t say jokes are unpatterned information.
Summarize Argument: Phenomenon-Hypothesis
Biologists hypothesize that fewer island plant species than mainland species have developed defenses to large mammals, and that’s why more island species have gone extinct. For evidence, they note that islands usually don’t have many large mammals until they’re settled by humans.
Notable Assumptions
The biologists assume island plants go extinct at higher rates than mainland plants because of large land mammals. This means assuming mainland plant species have gotten more exposure to large mammals than island species, either because large mammals were prevalent on mainlands before humans settled, or because most islands were settled more recently than mainlands. It also means assuming plants with more exposure to established large land mammals are more likely to develop defenses against them.
A
Most of the plant species in the world that have not yet gone extinct are native to mainland regions.
This doesn’t affect the argument. It doesn’t say islands and mainlands started out with a similar number of plant species, nor does it suggest large mammals are to blame for any discrepancy.
B
Many plant species that are not native to islands have become very well established on islands throughout the world.
This weakens the argument. It suggests competition from mainland plant species, not a sudden exposure to large mammals, has caused more island plants to go extinct.
C
Commercial development on many islands has resulted in loss of habitat for many native plants.
This weakens the argument. It suggests that commercial development, rather than large land mammals, is responsible for more island plants going extinct.
D
The rate of extinction of native plant species on an island tends to increase dramatically after human colonization.
This makes the biologists’ hypothesis more likely. It suggests island plant species are more likely to go extinct when large land mammals have been introduced.
E
Large land mammals tend to prefer plants from species native to mainland regions over plants from species native to islands.
If anything, this weakens the argument. It suggests large mammals don’t like to eat island plant species, making it less likely their introduction causes those species to go extinct.
Kendra: But unlike hearing music while walking by, accessing wireless service requires stopping for a considerable length of time. And that could be considered loitering or even harassment.
Speaker 1 Summary
Gerald concludes that people who access other’s wireless internet aren’t doing anything illegal. This is because such access is just like enjoying someone else’s music as you pass by them, which isn’t illegal.
Speaker 2 Summary
Kendra’s implicit conclusion is that accessing someone else’s wireless internet can be considered illegal. This is because such access requires stopping for a long time, unlike listening to a stranger’s music while walking by. Stopping for a long time to access someone else’s wireless internet could be considered the crimes of loitering or harassment.
Objective
We’re looking for a point of disagreement. The speakers disagree about whether accessing someone else’s wireless internet can be considered illegal.
A
can be considered illegal under current law
This is a point of disagreement. Gerald thinks it isn’t illegal under current laws. Kendra’s implicit point is that it can be considered illegal under current law, because it can be considered loitering or harassment.
B
is like trespassing
Not a point of disagreement. Kendra characterizes accessing another’s wireless internet as loitering or harassment, but does not indicate whether it can be characterized as trespassing.
C
should be prohibited by law
Neither speaker expresses an opinion. The dispute is about whether accessing another’s internet is illegal under current law. Whether it should be illegal is a separate issue.
D
requires a considerable length of time
Gerald doesn’t express an opinion about this. He doesn’t comment time or how much time is required to access someone else’s wireless internet.
E
could be done without intending to do so
Neither speaker expresses an opinion. They don’t refer to intention or whether accessing wireless internet would be done without intention.
Summarize Argument: Counter-Position
Some people think the Forestry Department is not doing their job properly if forest fires are not immediately extinguished. However, frequent small fires clear out small trees and forest debris. If these trees and debris were allowed to accumulate, this would create the conditions for more devastating fires. Therefore, it’s best to let small fires burn.
Identify Argument Part
The statement is used as evidence against the claim some people hold that the Forestry Department is not doing their job if they do not immediately extinguish fires.
A
It is offered as support for the contention that the Forestry Department is not doing its job properly if it does not extinguish forest fires as quickly as possible.
The statement does not support the the claim many people believe. Rather, it is used to support the claim that it’s best to let small fires burn.
B
It is used as evidence against the contention that the Forestry Department is not doing its job properly if it does not extinguish forest fires as quickly as possible.
The statement point out additional considerations that run counter to the claim many people think is true in the first sentence.
C
It is used to show what the consequences would be if the Forestry Department based its policies on the ideas most people have about how it should do its job.
The statement does not involve any consequences. The statement is presented as matter-of-fact.
D
It is an example used to illustrate the claim that most people believe the Forestry Department should quickly extinguish all forest fires.
The statement is not an example, and it does not support the claim most people believe about the Forestry Department.
E
It is a conclusion based on the premise in the argument that it is best to let small forest fires burn.
The statement is not a conclusion. The conclusion is that it’s best to let small fires burn.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that turmeric helps prevent Alzheimer’s disease. Why? First, because of a correlation: people in India eat lots of turmeric, and very few get Alzheimer’s disease. Second, because of turmeric’s effect on the brain: the curcumin it contains reduces the buildup of amyloid proteins that characterize Alzheimer’s disease, at least in animals.
Notable Assumptions
The author assumes eating turmeric makes more curcumin available for breaking down amyloid proteins in the brain, thus reducing the risk of Alzheimer’s disease. This means assuming curcumin has the same effect on amyloid proteins in humans that it does in animals. She also assumes the correlation in India—more people eat turmeric and fewer get Alzheimer’s disease—is because turmeric consumption reduces a person’s chances of Alzheimer’s disease, and not for some other reason.
A
Rosemary and ginger, which contain compounds that affect amyloid protein accumulation much like curcumin does, are commonly found in the diets of people living in India.
This weakens the argument. It suggests rosemary and ginger, not turmeric, could be responsible for the low rates of Alzheimer’s disease in India.
B
Many scientists believe that the buildup of amyloid protein plaques in the brain is a symptom of Alzheimer’s disease rather than a cause.
This weakens the argument. It implies breaking down amyloid proteins will not reduce the risk of Alzheimer’s disease, casting doubt on the stated benefit of curcumin.
C
The proportion of people living in India who fall within the age group that is most prone to developing Alzheimer’s disease is smaller than the proportion of people worldwide who fall within that age group.
This weakens the argument. It suggests fewer people get Alzheimer’s in India because fewer belong to the at-risk age group, not because of their turmeric consumption.
D
None of the other compounds found in turmeric have been studied to see whether they affect the accumulation of amyloid proteins.
This has no effect on the argument. It’s equally possible these other compounds in turmeric could promote or inhibit the accumulation of amyloid proteins.
E
The parts of India that have the highest per capita rates of curry consumption have the lowest incidence of Alzheimer’s disease.
This strengthens the correlation between high turmeric intake and low rates of Alzheimer’s disease. It implies the correlation extends to regions within India, making it more pronounced.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that the increased reports of tornadoes since the 1950s is probably explained by our finding a higher percentage of tornadoes that occur rather than an increase in the actual number of tornadoes. This is based on the fact that our ability to find tornadoes has improved since the 1950s.
Notable Assumptions
The author assumes that our ability to find tornadoes has increased enough to account entirely for the increased reports of tornadoes since 1950.
A
The physical damage caused by the average tornado has remained roughly constant since the 1950s.
The argument concerns whether the number of tornadoes has increased. The damage produced by an average tornado does not reveal anything about the overall number of tornadoes.
B
The number of tornadoes hitting major population centers annually has more than doubled since the 1950s.
If anything, this might undermine the argument by suggesting that there has been an increase in the number of tornadoes.
C
The number of large and medium sized tornadoes reported annually has remained roughly constant since the 1950s.
This suggests there hasn’t been an overall increase in actual tornadoes, because we’d expect all kinds of tornadoes to increase, not just the small ones. Instead, the explanation for the increased reports of small tornadoes might simply be easier identification of them.
D
The annual number of deaths due to tornadoes has increased steadily since the 1950s.
If anything, this might undermine the argument by suggesting that there might be more tornadoes (which would account for the increased deaths due to tornadoes).
E
The geographic range in which tornadoes are most prevalent has remained roughly constant since the 1950s.
This tells us that the range in which tornadoes are most common has been about the same. But the range staying the same doesn’t tell us anything about the overall frequency of tornadoes within that range.