Darla: Why think that air pollution would decrease? During a recession fewer people can afford to buy new cars, and cars tend to emit more pollutants as they get older.
Summarize Argument: Phenomenon-Hypothesis
Darla questions Charles’s claim that air pollution from automobile exhaust decreases during a recession. As evidence, she points out that during a recession fewer people can afford to buy new cars. Moreover the older the car, the more pollutants that car emits.
Describe Method of Reasoning
Darla’s response weakens the relationship between Charles’s evidence and his hypothesis. She does this by pointing out a fact Charles’s argument does not account for: people buy fewer new cars during a recession and older cars tend to emit more pollutants.
A
It calls into question the truth of the premises that Charles uses to support his conclusion.
Darla does not question Charles’s premises. She does not deny that unemployment typically rises during a recession, and she does not deny that during a recession fewer people commute in cars to jobs.
B
It makes an additional claim that can be true only if Charles’s conclusion is false.
Darla’s claims do not contradict Charles’s conclusion. She questions Charles’s conclusion, but this is not the same as disproving Charles’s conclusion.
C
It presents an additional consideration that weakens the support given to Charles’s conclusion by his evidence.
The additional consideration is that during a recession fewer people buy new cars, and older cars tend to emit more pollutants.
D
It argues that Charles’s conclusion is true, although not for the reasons Charles gives to support that conclusion.
Darla does not argue for the truth of Charles’s conclusion. In fact, she questions why Charles’s hypothesis would follow from his premises.
E
It presents an argument showing that the premises in Charles’s argument support an absurd conclusion that Charles has overlooked.
Darla’s claims point to a consideration Charles’s argument has overlooked, but she does not point to a conclusion that Charles has overlooked.
Summary
The author argues that if the condor is to survive in the wild, its population must increase. Their population will increase only if most of the condors' eggs hatch. However, the author suggests this is highly unlikely due to environmental dangers to the eggs. Thus, the author believes that breeding condors in captivity and releasing them into the wild will make the eggs hatching much more likely.
Strongly Supported Conclusions
If most condor eggs do not hatch, the population will not increase, and then the birds will not survive in the wild.
A
The condor as a species will eventually become extinct in the wild.
This is far too strong to support. The author suggests that breeding them in captivity could alleviate the pressures that destroy condor eggs.
B
The best way to save the condor from extinction is to breed it in captivity.
The stimulus does not suggest that breeding condors in captivity is the *best* way to save them from extinction. It is just provided as *a way* to ensure the hatching of more eggs.
C
It is almost impossible to eliminate all the environmental threats to the eggs of condors.
This is too strong to support. The stimulus says that eliminating all of the threats to eggs “in the wild” is extremely unlikely. Not that it is almost impossible in *every* context.
D
If more condor eggs do not hatch, the condor as a species will not survive in the wild.
This is the reasoning in the stimulus. If the condor is to survive, the population must increase. If the population increases, most of the eggs will hatch. Run the contrapositive, and that’s the answer.
E
The most feasible way to save the condor from extinction is to increase egg production.
The stimulus is focused on increasing the hatching success rate, not the rate of egg production itself.
Summarize Argument: Counter-Position
The astronomer considers an argument held by many people and concludes that it is possible to have both well-lighted streets and relatively dark skies. As evidence, the astronomer points out that in Sandsville the local observatory’s view is clear because the city has both restricted unnecessary lighting and installed street lamps that direct all light downward.
Describe Method of Reasoning
The astronomer counters a position held by others. She does this by offering a counterexample. It is not true that interference from lights is inevitable because in Sandsville relatively dark skies are achieved by restricting unnecessary lighting and installing special street lamps.
A
appealing to a scientific authority to challenge a widely held belief
The astronomer does not appeal to a scientific authority. We cannot assume that just because the argument is made by an astronomer that the argument appeals to scientific authority.
B
questioning the accuracy of evidence given in support of the opposing position
The astronomer does not question that streetlights are needed for safety. The astronomer addresses the conclusion believed by others, not their premises.
C
proposing an alternative scientific explanation for a natural phenomenon
The astronomer does not propose an alternative explanation for light interference.
D
making a distinction between terms
The astronomer does not distinguish any terms.
E
offering a counterexample to a general claim
The general claim is other people’s argument that interference from light is inevitable. The counterexample the astronomer offers is the city of Sandsville, which does not experience light interference.
A
denies that an observation that a trait is common to all the events in a pattern can contribute to a causal explanation of the pattern
The trait (A) is referencing is self-interest and the pattern is human action, but the author doesn’t say that self-interest can’t contribute to a causal explanation of human action. On the contrary, the author argues that self-interest is the main influence on human action.
B
takes the occurrence of one particular influence on a pattern or class of events as showing that its influence outweighs any other influence on those events
The author argues that simply because self-interest influences motives that influence all human actions, self-interest outweighs any other influences on human actions. The author errs by never addressing how self-interest is the main influence on human actions.
C
concludes that a characteristic of a pattern or class of events at one time is characteristic of similar patterns or classes of events at all times
The author never argues that self-interest influences human actions at some times and, therefore, influences similar patterns or classes of events at all times. He only argues that self-interest is the principal influence on human actions.
D
concludes that, because an influence is the paramount influence on a particular pattern or class of events, that influence is the only influence on that pattern or class of events
The author doesn’t make the case that self-interest is the only influence on human action. He just argues that self-interest is the chief influence on human action.
E
undermines its own premise that a particular attribute is present in all instances of a certain pattern or class of events
The author’s only premise is that motives that influence all human actions come from self-interest. He never undermines this premise.
Summarize Argument: Phenomenon-Hypothesis
The agricultural official presents the hypothesis that a new pesticide is more effective than the old pesticide at protecting pears against insects, at least over a short-term period. This hypothesis is based on observing that when pear farmers in District 10 switched from the old pesticide to the new pesticide for 3 years, they lost fewer pears to insects than during the previous 3 years.
Notable Assumptions
The agricultural official assumes that just because there were fewer pears lost to insects while the new pesticide was in use, the new pesticide was the cause of this change. In other words, the official assumes that there wasn’t some other factor which could have been the true cause of the farmers’ results.
A
The amount of fruit that an orchard can potentially produce depends in part on how many mature trees it contains, and the number of mature pear trees in District 10 has declined steadily over the past eight years.
This does not weaken, and so is the correct answer. This claim doesn’t explain why there would be fewer pears lost to insects in the last 3 years. Overall pear production can change without affecting the proportion of pears that insects destroy, so this just gives us nothing.
B
During the past five years, the farmers of the District 10 Farmers’ Cooperative have been gradually implementing a variety of insect-abatement programs, and some of these programs have proven successful.
This weakens the argument by providing an alternative explanation for the observation. If the pear farmers have been gradually implementing anti-insect programs, then it makes sense that the last 3 years would see fewer insect losses.
C
Over the past five years, one of the several species of birds that typically prey on the insects that feed on pears has gradually shifted its migratory patterns, spending more and more months each year in the region that contains District 10.
This weakens the argument by providing an alternative explanation for the observation. If insect-eating birds have been spending more time around District 10, they would have eaten more insects, thus protecting the pears.
D
Some of the species of insects in District 10 that infest pear trees are water breeders, and the reservoirs and marshlands in this district have been shrinking rapidly over the past three years.
This weakens the argument by providing an alternative explanation for the observation. If pear-eating insects have had less water in which to breed, then there would be fewer insects, which explains why there have been fewer pears eaten by insects.
E
The effects of certain pesticides, including the pesticide that had formerly been used in District 10, are cumulative and persist for several years after the pesticide is no longer applied.
This weakens the argument by providing an alternative explanation for the observation. If the effects of the old pesticide get stronger with each use and last for years, then the pears would have been protected by a strong built-up effect during the 3 years in question.
Summarize Argument
The newsletter concludes that volunteering can benefit one’s well-being. It supports this by noting that retired people who volunteer tend to show fewer signs of aging than retired people who don’t, and that volunteers are stronger socially, mentally, physically, and economically than non-volunteers.
Identify and Describe Flaw
This is a cookie-cutter “correlation does not imply causation” flaw, where the newsletter sees a positive correlation and then jumps to the conclusion that one thing causes the other, without ruling out alternative hypotheses. Specifically, it overlooks two key alternatives:
(1) The causal relationship could be reversed— maybe stronger people tend to volunteer more, not the other way around.
(2) Some other, underlying factor could be causing the correlation—maybe there’s something that causes people to both be stronger and to volunteer.
A
the center has a self-interested motive to attract new volunteers
This might be true; we don’t have enough information to know either way. But even if it is true, (A) doesn't describe the logical flaw in the newsletter’s argument. It’s based on that logical flaw that “the inference drawn above is unwarranted.”
B
it interprets “well-being” as including the factors of social and economic resources, mental outlook, physical health, and overall functioning
This is true, but it doesn’t describe the flaw in the newsletter’s argument. Interpreting “well-being” in this way is entirely reasonable.
C
some of those who do not volunteer might be older than some volunteers and so could not be considered their peers
This is true, but it doesn’t describe the flaw in the newsletter’s argument. Some of those who don’t volunteer might also be younger than some volunteers; it doesn’t matter to the argument, which only compares retired volunteers with their “nonvolunteering contemporaries.”
D
growing older might not necessarily result in a change in mental outlook
This might be true, but it doesn't describe the flaw in the newsletter’s argument. The argument assumes that volunteering causes a stronger mental outlook. It doesn’t assume that growing older causes a change in mental outlook.
E
those with better resources, health, outlook, and functioning are more able to work as volunteers
This describes an alternative hypothesis that the author ignores. She assumes that volunteering causes increased well-being, without considering that instead, those with a higher well-being might be more likely or more able to volunteer.
Summarize Argument
The stimulus only offers a set of facts, not an argument; instead, the question stem tells us to weaken the claim that the traditional treatment for flat-footedness in children is effective. This treatment, according to the stimulus, is to give flat-footed children shoes with extra support, with the goal of fostering arch development.
Notable Assumptions
The claim that the traditional treatment for flat-footedness in children is effective is based on the assumption that wearing shoes with extra support actually does improve arch development. The stimulus doesn’t provide any data to support this, so it’s just an assumption.
A
Many small children who have normal feet wear the same special shoes as those worn by flat-footed children.
This does not undermine the effectiveness of the traditional treatment. Whether or not children with normal feet also wear these special shoes doesn’t tell us anything about the effects of those shoes on arch development. This is just irrelevant.
B
Studies of flat-footed adults show that flat feet are subject to fewer stress fractures than are feet with unusually high arches.
This does not undermine the effectiveness of the traditional treatment. We’re not interested in the pros and cons of flat feet versus high arches, we’re interested in whether the treatment for flat-footedness actually works. This doesn’t help with that at all.
C
Although most children’s flat-footedness is corrected by the time the children reach puberty, some people remain flat-footed for life.
This does not undermine the effectiveness of the traditional treatment. This doesn’t tell us whether or not there’s any relationship between wearing special shoes and the improvement of flat-footedness, it’s just irrelevant.
D
Flat-footed children who do not wear the special shoes are as likely to develop natural arches as are flat-footed children who wear the special shoes.
This undermines the effectiveness of the traditional treatment by rebutting the assumption that wearing special shoes actually improves arch development. If there’s no correlation between treatment and arch development, we can’t call the treatment effective.
E
Some children who are not flat-footed have hip and lower leg bones that are rotated excessively either inward or outward.
This does not undermine the effectiveness of the traditional treatment. We’re only interested in the correction of flat-footedness, so a fact about non-flat-footed children is totally outside the domain of this question.
Environmentalist: To claim that we should let species disappear because all species eventually die out makes about as much sense as arguing that we should not spend money to find a cure for cancer because all humans are inevitably mortal.
Summarize Argument: Counter-Position
In response to the land developer’s claim that it is a waste of money attempting to preserve species that will disappear regardless of efforts, the environmentalist points out that this claim is similar to concluding we should not spend money to cure cancer because humans are mortal.
Describe Method of Reasoning
The environmentalist counters the position held by the land developer. He does this by presenting an analogous argument with an obviously indefensible conclusion.
A
clarify a dilemma that is embedded in the land developer’s argument
There is no dilemma in the land developer’s argument. The land developer does not present a situation where a difficult choice needs to be made between two or more solutions.
B
attack the character of the land developer rather than the position the land developer is taking
The environmentalist does not attack the land developer’s character. He addresses the land developer’s argument directly.
C
show that more evidence is needed to substantiate the land developer’s conclusion
The environmentalist does not state that the land developer’s argument requires more evidence. His position is that the land developer’s argument is ridiculous.
D
show that the land developer’s line of reasoning would lead to an unacceptable conclusion if applied to a different situation
The analogous situation is spending money in order to find a cure for cancer.
E
argue that there are problems that money, however judiciously spent, cannot solve
The environmentalist does not state that money cannot solve some problems.