The question stem reads: The biologist’s argument is most vulnerable to criticism on which one of the following grounds? This is a Flaw question.

The biologist begins by describing how many paleontologists suggest that the difficulties of the ice age were a cause of the evolution of the human brain. The biologist concludes those palentologists are wrong. In other words, the ice age was not responsible for the evolution of the human brain. As evidence, the biologist cites that many animal species survived the ice age with no evolutionary changes to their brain.

The biologist has hypothesized that the ice age was not repsonsbile for the evolution of the human brain. If we were to construct an ideal experiment to test this hypothesis, what kind of subjects would you want to use? You would want to use human brains! However, the biologist instead uses animals brains as evidence. The question is, “Are humans and animals” the same? Maybe. Maybe not. The biologist’s argument relies on the assumption that humans and animals would respond to the evolutionary pressures of the ice age in the same way. So let’s look for an answer choice that distinguishes how animal brains and human brains would respond to the ice age.

Answer Choice (A) is incorrect. The biologist does not suggest that the ice age was sufficient or necessary to produce brain evolution in humans or animals.

Correct Answer Choice (B) draws the distinction between humans and animals that we are looking for. The biologist fails to consider the possibility that the ice age could have produced the evolution of the brain in humans without producing the evolution of the brain in other species.

Answer Choice (C) is incorrect. The argument is not about whether the ice age was necessary for producing changes in the brains of humans or animals. The argument is about whether the ice age was sufficient to bring about changes in the brains of humans and animals.

Answer Choice (D) is incorrect. The biologist never presumes that humans had a more difficult time during the ice age than animals.

Answer Choice (E) is incorrect. The biologist does not presume that the ice age was causally responsible for the evolution of human brains. He concludes that the ice age was not casusualy responsible for the evolution of human brains.


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The total number of book titles published annually in North America has approximately quadrupled since television first became available. Retail sales of new titles, as measured in copies, increased rapidly in the early days of television, though the rate of increase has slowed in recent years. Library circulation has been flat or declining in recent years.

Summary
The stimulus says that four times as many new books are published in North America each year, compared to when television first became available. Also, shortly after television’s debut, new books sold at much faster rates than before. Now, more books are still selling each year, but the rate of increase is slowing down. However, recently, library use has been flat or falling.

Strongly Supported Conclusions
The stimulus lets us infer these conclusions:
The arrival of television in North America did not lead to a decline in new book publications or in book sales.
An increase in new books sold each year does not always coincide with an increase in library circulation.

A
Television has, over the years, brought about a reduction in the amount of per capita reading in North America.
This is not supported. The facts do not directly address per capita reading, and we also don’t have enough information to make an inference. How much has the population grown compared to book sales? Do book sales reflect reading rates? We don’t know.
B
The introduction of television usually brings about a decrease in library use.
This is not supported. We only have information about one situation with television and books in North America, so we can’t conclude that anything “usually” happens. Also, we don’t know of any causal link between television and library use.
C
Book publishers in North America now sell fewer copies per title than they sold in the early days of television.
This is not supported. The facts don’t include any information about the proportion between new book titles and total books sold, so we can’t say if those numbers balance differently than they used to.
D
The availability of television does not always cause a decline in the annual number of book titles published or in the number of books sold.
This is strongly supported. Based on the stimulus, since television was introduced in North America, there have been increases in book titles published and total books sold. Thus, television can’t have caused a decline, meaning it must not always cause a decline.
E
The introduction of television expanded the market for books in North America.
This is not supported. We know that books started selling faster after television was introduced, but we have no idea if there’s a causal link between those events. All we have is a correlation!

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Botanist: It has long been believed that people with children or pets should keep poinsettia plants out of their homes. Although this belief has been encouraged by child-rearing books, which commonly list poinsettias as poisonous and therefore dangerous, it is mistaken. Our research has shown, conclusively, that poinsettias pose no risk to children or pets.

Summarize Argument: Counter-Position
The botanist refutes a belief with research: The belief that people with children or pets should not have poinsettia plants in their homes is mistaken. The botanist’s research shows, definitively, that the plants are not dangerous for those groups.

Identify Conclusion
The conclusion is the botanists refutation of the belief that poinsettia plants are dangerous: “it is mistaken.”

A
Child-rearing books should encourage people with children to put poinsettias in their homes.
This answer choice goes too far. The author says that the belief that the plants are dangerous is mistaken. She does not say that child-rearing books “should” do anything.
B
Poinsettias are not dangerously poisonous.
This answer choice is not contained in the stimulus. The botanist’s research shows that there is no risk to children or pets, but she is not making a claim about how poisonous the plants are. Perhaps they are dangerously poisonous to groups that are not children/pets.
C
According to many child-rearing books, poinsettias are dangerous.
This is part of the context that sets up the botanist’s argument.
D
The belief that households with children or pets should not have poinsettias is mistaken.
This accurately paraphrases the conclusion. “It” - the belief that poinsettias should not be in homes with pets or children, is mistaken.
E
Poinsettias pose no risk to children or pets.
This is the result of the research that the botanist uses in the premise. It supports her conclusion that the belief about poinsettias is mistaken.

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When a threat to life is common, as are automobile and industrial accidents, only unusual instances tend to be prominently reported by the news media. Instances of rare threats, such as product tampering, however, are seen as news by reporters and are universally reported in featured stories. People in general tend to estimate the risk of various threats by how frequently those threats come to their attention.

Summary
In situations that commonly threaten people’s lives (like car crashes and industrial accidents), the news only really reports unusual incidents. However, rare threats like product tampering are prominently reported. Also, people generally estimate the risk of different threats based on how much they hear about those threats.

Strongly Supported Conclusions
The stimulus supports these conclusions:
News media are more likely to report on rare or unusual threats to life than on common threats.
People who estimate risk based on news reports likely underestimate the risk of common threats and overestimate the risk of rare or unusual threats.

A
Whether governmental action will be taken to lessen a common risk depends primarily on the prominence given to the risk by the news media.
This is not supported. The stimulus doesn’t mention or allude to government action at all, so we have no basis to conclude when the government will or won’t act to lessen a risk.
B
People tend to magnify the risk of a threat if the threat seems particularly dreadful or if those who would be affected have no control over it.
This is not supported. The facts given don’t suggest anything about threats seeming dreadful or how much control the people affected have. So, the facts don’t support any conclusion on those points.
C
Those who get their information primarily from the news media tend to overestimate the risk of uncommon threats relative to the risk of common threats.
This is strongly supported. People estimate risk based on how often they hear about threats. The news rarely reports on common threats but often reports on rare threats, so someone who gets information from the news would hear more about rare threats, and thus overestimate them.
D
Reporters tend not to seek out information about long-range future threats but to concentrate their attention on the immediate past and future.
This is not supported. We never learn about what information people tend to seek out, or any other distinction about long-range versus immediate threats. So, we can’t draw any conclusion about this.
E
The resources that are spent on avoiding product tampering are greater than the resources that are spent on avoiding threats that stem from the weather.
This is not supported. All we know is that the news media will report rare threats like product tampering. We don’t know anything about how that might translate to resources being spent on protection.

4 comments

The question stem reads: The argument is most vulnerable to criticism on which one of the following grounds? This is a Flaw question.

The author begins by stating how many parents organize their child's playtime in order to enhance their child's cognitive development. The author concludes that the parents' belief is incorrect: Organizing a child's playtime will not enhance cognitive development. To prove their claim, the author says, "To thoroughly structure a child's playtime and expect this to produce a creative and resourceful child would be like expecting a good novel to be produced by someone who was told exactly what the plot and characters must be."

What a minute. Is producing "a creative and resourceful child" the reason parents organize playtime? All we know is that the parents organized play time to enhance cognitive development. Creativity and resourcefulness are a subset of cognitive functions. So there could be cognitive functions the parents want to enhance besides creativity and resourcefulness. Perhaps the parents organize playtime to improve a child's ability to organize. Shocking! So the author has failed to consider that organized playtime might enhance cognitive development in areas besides creativity and resourcefulness.

Answer Choice (A) is incorrect. The author wants to say organized playtime is not conducive to enhancing cognitive development. (A) would look better if it said, "Takes for granted that if something (organized playtime is not conducive to a certain goal (developing creativity and resourcefulness), it also cannot be conducive to some other goal (enhancing cognitive development).

Answer Choice (B) is overlooked by the argument but is also irrelevant. Whether or not children enjoy organized playtime is arbitrary.

Answer Choice (C) is also incorrect. The author never considers organized playtime to be necessary for enhancing a child's creativity and resourcefulness.

Answer Choice (D) has nothing to do with the argument. The author never actually says writing a good novel requires creativity and resourcefulness. The author claims you can't expect a good book to be written by someone who is told what characters and plot to use.

Correct Answer Choice (E) is what we discussed. The author does fail to consider that organized playtime could enhance other aspects of cognitive development (which would improve overall cognitive development) without enhancing creativity and resourcefulness.


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Scientists studying a common type of bacteria have discovered that most bacteria of that type are in hibernation at any given time. Some microbiologists have concluded from this that bacteria in general are usually in hibernation. This conclusion would be reasonable if all types of bacteria were rather similar. But, in fact, since bacteria are extremely diverse, it is unlikely that most types of bacteria hibernate regularly.

Summarize Argument: Counter-Position
It is unlikely that most types of bacteria hibernate regularly. Some microbiologists claim that most bacteria hibernate regularly, but they base that off of a study of one type of bacteria - which is a problem because types of bacteria are different, not similar.

Identify Conclusion
The conclusion is the author’s claim about bacterial hibernation: “it is unlikely that most types of bacteria hibernate regularly.”

A
Bacteria of most types are usually in hibernation.
This is the claim of some microbiologists that the author refutes.
B
It is probably not true that most types of bacteria hibernate regularly.
This accurately rephrases the conclusion that it is unlikely (probably not true) that most types of bacteria hibernate regularly.
C
If bacteria are extremely diverse, it is unlikely that most types of bacteria hibernate regularly.
The “if” statement makes this answer choice incorrect. The author establishes that bacteria are extremely diverse in a premise. The conclusion of the argument is not conditional.
D
The conclusion that bacteria in general are usually in hibernation would be reasonable if all types of bacteria were rather similar.
This is a premise that sets up why that conclusion is not reasonable. The author combines this with the fact that bacteria are diverse to refute that conclusion.
E
It is likely that only one type of bacteria hibernates regularly.
This answer choice goes too far. The author concludes that it is unlikely that most types hibernate regularly, but that does not mean that only type does.

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