Legal theorist: Governments should not be allowed to use the personal diaries of an individual who is the subject of a criminal prosecution as evidence against that individual. A diary is a silent conversation with oneself and there is no relevant difference between speaking to oneself, writing one’s thoughts down, and keeping one’s thoughts to oneself.

Summarize Argument
The legal theorist concludes that governments shouldn’t be allowed to use a person’s diary as evidence against them in a criminal prosecution. She supports this by saying that a diary is a conversation with oneself and there’s no real difference between talking to oneself, writing down one’s thoughts, and keeping those thoughts private.

Notable Assumptions
The legal theorist assumes that governments shouldn’t use a person’s words— whether spoken or written— against them if those words are only meant for that person herself.

A
Governments should not be allowed to compel corporate officials to surrender interoffice memos to government investigators.
The legal theorist is only talking about individual people and their private diaries. Interoffice memos are not analogous to diaries. Diaries are a private conversation with oneself, while interoffice memos are shared throughout an office.
B
When crime is a serious problem, governments should be given increased power to investigate and prosecute suspected wrongdoers, and some restrictions on admissible evidence should be relaxed.
The legal theorist is advocating for a specific restriction on admissible evidence used in government investigations, while (B) supports loosening some of these restrictions. (B) also fails to address why a person’s private words shouldn’t be used against them.
C
Governments should not be allowed to use an individual’s remarks to prosecute the individual for criminal activity unless the remarks were intended for other people.
This suggests that governments should never use a person’s words against them if those words were meant only for the person herself. This supports the idea that the government shouldn’t use someone’s diary as evidence against them.
D
Governments should not have the power to confiscate an individual’s personal correspondence to use as evidence against the individual in a criminal trial.
The legal theorist is discussing words directed to oneself, whether spoken or written. Correspondence isn’t analogous to a private diary because it’s between two or more people.
E
Governments should do everything in their power to investigate and prosecute suspected wrongdoers.
This weakens the argument because the legal theorist wants to limit what governments can do in investigations, while (E) argues that governments should do everything in their power. Presumably “everything” includes using someone’s personal diary against them.

9 comments

A ring of gas emitting X-rays flickering 450 times per second has been observed in a stable orbit around a black hole. In light of certain widely accepted physical theories, that rate of flickering can best be explained if the ring of gas has a radius of 49 kilometers. But the gas ring could not maintain an orbit so close to a black hole unless the black hole was spinning.

Summary

Scientists have seen a ring of gas that maintains a stable orbit around a black hole. The gas ring emits X-rays that flicker 450 times per second. This flickering speed suggests that the gas ring has a radius of 49 kilometers, meaning that it is very close to the black hole. However, for the gas ring to maintain its orbit so close to the black hole, the black hole itself must be spinning.

Strongly Supported Conclusions

In some conditions, gas can orbit black holes at a close distance.

The black hole is spinning.

A
Black holes that have orbiting rings of gas with radii greater than 49 kilometers are usually stationary.

This is unsupported. We know only that black holes that have orbiting rings of gas with radii of 49 kilometers must be spinning. We do not know the conditions of black holes that have orbiting rings of gas with radii greater than 49 kilometers.

B
Only rings of gas that are in stable orbits around black holes emit flickering X-rays.

This is unsupported. The stimulus only tells us about this particular ring of gas. We do not have any information about the emissions of any other rings of gas.

C
The black hole that is within the ring of gas observed by the astronomers is spinning.

This is strongly supported. We know that the gas ring has been observed in a stable orbit very close to the black hole. Because the ring can only maintain such a close orbit if the black hole is spinning, we can conclude that the black hole is spinning.

D
X-rays emitted by rings of gas orbiting black holes cause those black holes to spin.

This is unsupported. The stimulus tells us that the black hole must be spinning based on the observed facts of the gas ring. However, it does not tell us what causes the black hole to spin.

E
A black hole is stationary only if it is orbited by a ring of gas with a radius of more than 49 kilometers.

This is unsupported. We know only that a black hole orbited by a gas ring with a radius of 49 kilometers must not be stationary. We do not know the conditions required for a black hole to be stationary.


36 comments

Many nurseries sell fruit trees that they label “miniature.” Not all nurseries, however, use this term in the same way. While some nurseries label any nectarine trees of the Stark Sweet Melody variety as “miniature,” for example, others do not. One thing that is clear is that if a variety of fruit tree is not suitable for growing in a tub or a pot, no tree of that variety can be correctly labeled “miniature.”

Summary
Fruit trees can only be correctly labeled as “miniature” if they can be grown in a tub or pot.
Some nurseries label Stark Sweet Melody trees as “miniature.”

Very Strongly Supported Conclusions
Stark Sweet Melody nectarine trees can only be correctly labeled as “miniature” if they can be grown in a tub or pot.
If Stark Sweet Melody trees can’t be grown in a tub or pot, then some nurseries mislabel them.

A
Most nurseries mislabel at least some of their fruit trees.
Unsupported. Not all nurseries use the term “miniature” in the same way. Some might be mislabeling their fruit trees as “miniature,” but we don’t know that most are.
B
Some of the nurseries have correctly labeled nectarine trees of the Stark Sweet Melody variety only if the variety is unsuitable for growing in a tub or a pot.
Anti-supported. Some nurseries have correctly labeled Stark Sweet Melody trees only if these trees are suitable for growing in a tub or pot. If they’re not suitable for growing in a tub or pot, then some nurseries have incorrectly labeled them as “miniature.”
C
Any nectarine tree of the Stark Sweet Melody variety that a nursery labels “miniature” is labeled incorrectly.
Unsupported. Stark Sweet Melody trees might be suitable for growing in a tub or pot. If they are, we can’t conclude that they’re labeled incorrectly.
D
Some nectarine trees that are not labeled “miniature” are labeled incorrectly.
Unsupported. We only know that trees that are labeled “miniature” are labeled incorrectly if they can’t be grown in a tub or a pot. We don’t know what makes not labeling a tree “miniature” correct or incorrect.
E
Unless the Stark Sweet Melody variety of nectarine tree is suitable for growing in a tub or a pot, some nurseries mislabel this variety of tree.
Very strongly supported. Fruit trees can only be correctly labeled as “miniature” if they can be grown in a tub or pot. If Stark Sweet Melody trees are not suitable for growing in a tub or pot, then some nurseries mislabel them.

22 comments

Psychologist: Identical twins are virtually the same genetically. Moreover, according to some studies, identical twins separated at birth and brought up in vastly different environments show a strong tendency to report similar ethical beliefs, dress in the same way, and have similar careers. Thus, many of our inclinations must be genetic in origin, and not subject to environmental influences.

Summarize Argument: Phenomenon-Hypothesis

The psychologist hypothesizes that many of our inclinations are genetic and are not influenced by environment. He bases this on studies showing that identical twins separated at birth and raised in different environments often report similar ethical beliefs, dress, and careers.

Notable Assumptions

The psychologist assumes that genetics are the cause of the separated twins’ similar inclinations, without considering other factors or experiences that might influence them.

He also assumes that the studies of identical twins raised in different environments are representative of all identical twins, and that these findings can be generalized to support the idea that genetics are primarily responsible for many inclinations.

A
Many people, including identical twins, undergo radical changes in their lifestyles at some point in their lives.

(A) doesn’t suggest that one twin changes radically while the other remains the same. It could be that both twins undergo similar changes, which doesn’t weaken the psychologist’s conclusion that our traits are more influenced by genetics than environment.

B
While some studies of identical twins separated at birth reveal a high percentage of similar personality traits, they also show a few differences.

The psychologist concludes that many, not all, of our inclinations are genetic rather than environmental. The fact that some studies show a few differences in identical twins separated at birth does not weaken this conclusion.

C
Scientists are far from being able to link any specific genes to specific inclinations.

The fact that scientists can’t pinpoint exactly which genes cause certain traits doesn’t weaken the idea that those traits are genetically determined. Thus, (C) doesn’t weaken the psychologist’s conclusion.

D
Identical twins who grow up together tend to develop different beliefs, tastes, and careers in order to differentiate themselves from each other.

This weakens the psychologist’s conclusion by providing evidence that directly contradicts it. If identical twins raised together often have different beliefs, tastes, and careers, these inclinations can’t be solely genetic.

E
Twins who are not identical tend to develop different beliefs, tastes, and careers.

The psychologist is only drawing a conclusion about identical twins. So the inclinations of twins who are not identical are irrelevant and don’t weaken the psychologist’s argument.


54 comments

Human beings can live happily only in a society where love and friendship are the primary motives for actions. Yet economic needs can be satisfied in the absence of this condition, as, for example, in a merchant society where only economic utility motivates action. It is obvious then that human beings _______.

Summary

People must live in a society primarily motivated by love and friendship in order to be happy. However, their economic needs can still be met outside of such a society. For example, humans’ economic needs can be met in a society that’s just motivated by economic utility.

Strongly Supported Conclusions

Human beings can have their economic needs met and still be unhappy.

Human beings cannot be happy in a society motivated primarily by economic utility.

A
can live happily only when economic utility is not a motivator in their society

This is unsupported. The stimulus says that love and friendship must be the primary motivators of a society in order for people to be happy. As far as we know, economic utility can still be one of the society’s motivators, it just must not be the primary motivator.

B
cannot achieve happiness unless their economic needs have already been satisfied

This is unsupported. The satisfaction of economic needs is not presented as necessary for happiness. Rather, a society motivated by love and friendship is necessary. Perhaps one could live in a society motivated by love, be economically unsatisfied, and still be happy.

C
cannot satisfy economic needs by means of interactions with family members and close friends

This is unsupported. The stimulus does not give us any information about whether a person can or cannot satisfy their economic needs through family and friends. We only know that economic needs can be satisfied in a society “where only economic utility motivates action.”

D
can satisfy their basic economic needs without obtaining happiness

This is strongly supported. Humans must live in a society primarily motivated by love and friendship in order to obtain happiness. Humans can satisfy their basic economic needs outside of such a society. Thus, humans can satisfy their economic needs without obtaining happiness.

E
cannot really be said to have satisfied their economic needs unless they are happy

This is anti-supported. The stimulus tells us that humans can satisfy their economic needs in a society primarily motivated by economic utility. In such a society, people are not happy. So a person does not need to be happy in order to be economically satisfied.


9 comments

Technologically, it is already possible to produce nonpolluting cars that burn hydrogen rather than gasoline. But the national system of fuel stations that would be needed to provide the hydrogen fuel for such cars does not yet exist. However, this infrastructure is likely to appear and grow rapidly. A century ago no fuel-distribution infrastructure existed for gasoline-powered vehicles, yet it quickly developed in response to consumer demand.

Summarize Argument
The infrastructure for hydrogen-powered cars is likely to grow quickly, even though it doesn’t exist yet. This is because, just as gas stations expanded rapidly when gasoline-powered vehicles became popular, we expect hydrogen fuel stations will follow the same pattern.

Identify Conclusion
The fuel infrastructure for hydrogen-powered cars will likely develop and expand quickly.

A
It is already technologically possible to produce nonpolluting cars that burn hydrogen rather than gasoline.
This is context. It provides background information on the current feasibility of hydrogen-powered cars and sets the stage for the author's argument that the fuel-distribution infrastructure for these cars will likely develop quickly.
B
The fuel-distribution infrastructure for hydrogen-powered cars still needs to be created.
This is context. The need to create a fuel infrastructure for hydrogen-powered cars sets the stage for the author's argument that such infrastructure will develop and expand quickly.
C
If a new kind of technology is developed, the infrastructure needed to support that technology is likely to quickly develop in response to consumer demands.
This is an unstated premise. The author assumes that, like the rapid development of fuel infrastructure for gas-powered cars, the same will happen for hydrogen-powered cars because the infrastructure needed to support new technologies quickly develops due to consumer demands.
D
The fuel-distribution infrastructure for hydrogen-powered cars is likely to appear and grow rapidly.
This captures the argument's main conclusion. The stimulus concludes that "this infrastructure"—referring to the fuel infrastructure needed for hydrogen-powered cars—"is likely to appear and grow rapidly," which this answer choice correctly restates.
E
Hydrogen-powered vehicles will be similar to gasoline-powered vehicles with regard to the amount of consumer demand for their fuel-distribution infrastructure.
The stimulus doesn't make this argument. It concludes that consumer demand will drive the growth of hydrogen fuel infrastructure, similar to gasoline, but it doesn't claim that both will have the same level of demand—only that each has enough to spur rapid infrastructure growth.

15 comments

Wildlife management experts should not interfere with the natural habitats of creatures in the wild, because manipulating the environment to make it easier for an endangered species to survive in a habitat invariably makes it harder for nonendangered species to survive in that habitat.

Summarize Argument
The author argues that experts should not change natural habitats to help endangered species because doing so always comes at the expense of nonendangered ones.

Identify and Describe Flaw
The argument fails to consider the possibility that helping endangered species is higher-priority than helping nonendangered ones. By definition, endangered species are at greater risk of extinction and likely need more support. Refusing to change a habitat to protect them, especially when nonendangered species can probably thrive elsewhere, overlooks the urgency of preventing extinction.

A
fails to consider that wildlife management experts probably know best how to facilitate the survival of an endangered species in a habitat
This is irrelevant because the argument doesn’t question experts’ ability to help endangered species. It’s only concerned with the negative effect it would have on other species.
B
fails to recognize that a nonendangered species can easily become an endangered species
This possibility does not pose a problem for the argument. The author recognizes that nonendangered species can be harmed since the author advocates for prioritizing their protection.
C
overlooks the possibility that saving an endangered species in a habitat is incompatible with preserving the overall diversity of species in that habitat
This is irrelevant since the author doesn’t advocate for saving an endangered species, but rather, argues that endangered species should not be saved if it means interfering with their habitat.
D
presumes, without providing justification, that the survival of each endangered species is equally important to the health of the environment
The author doesn’t equate anything to the health of the environment. He only presumes that endangered species are not higher-priority than nonendangered ones.
E
takes for granted that preserving a currently endangered species in a habitat does not have higher priority than preserving species in that habitat that are not endangered
This describes how the author fails to consider that saving a species in danger of extinction may be more important than helping species that aren’t at risk.

13 comments

Any food that is not sterilized and sealed can contain disease-causing bacteria. Once sterilized and properly sealed, however, it contains no bacteria. There are many different acceptable food-preservation techniques; each involves either sterilizing and sealing food or else at least slowing the growth of disease-causing bacteria. Some of the techniques may also destroy natural food enzymes that cause food to spoil or discolor quickly.

Summary
Any food that is not sterilized and sealed can contain disease-causing bacteria.
Any food that has been sterilized and properly sealed does not contain bacteria.
Some acceptable food-preservation techniques involve sterilizing and sealing food.
Some acceptable food-preservation techniques involve slowing the growth of disease-causing bacteria.
Some acceptable food-preservation techniques may destroy natural food enzymes that cause food to spoil or discolor quickly.

Notable Valid Inferences
It is possible to preserve food in an acceptable way without entirely eliminating disease-causing bacteria.
If a food has been preserved without being sterilized or sealed, that food could contain disease-causing bacteria.

A
All food preserved by an acceptable method is free of disease-causing bacteria.
Must be false. The stimulus states that some acceptable food-preservation techniques involve slowing the growth of disease-causing bacteria, rather than eliminating them completely.
B
Preservation methods that destroy enzymes that cause food to spoil do not sterilize the food.
Could be false. The stimulus is vague about which techniques destroy natural food enzymes, so it’s possible that a sterilization technique might do so.
C
Food preserved by a sterilization method is less likely to discolor quickly than food preserved with other methods.
Could be false. The stimulus is vague about which techniques destroy natural food enzymes and thereby cause food to discolor less quickly, so it’s possible that sterilization does not have this effect.
D
Any nonsterilized food preserved by an acceptable method can contain disease-causing bacteria.
Must be true. The stimulus explicitly states that any food that has not been both sterilized and properly sealed can contain disease-causing bacteria!
E
If a food contains no bacteria, then it has been preserved by an acceptable method.
Could be false. The stimulus doesn’t say that only sterilized and sealed (and thus acceptably preserved) food can be bacteria-free; rather, it tells us that all food that has been sterilized and sealed is bacteria-free. (E) confuses the necessary and sufficient conditions.

52 comments