Summarize Argument: Phenomenon-Hypothesis
The scientist hypothesizes that the ferrous material promoted a great increase in the population of Antarctic algae. She supports this by noting that algae absorb carbon dioxide from the atmosphere.
Notable Assumptions
The scientist assumes that more ferrous material leads to more algae, which in turn absorbs carbon dioxide. This means she assumes that the relationship isn’t the reverse (i.e. more algae leads to more ferrous material), and also that there isn’t some other, hidden cause that’s actually responsible for the amount of algae. The scientist also assumes that algae was actually present in Antarctica at this time, in quantities sufficient to draw her conclusion.
A
Diatoms are a microscopic form of algae that has remained largely unchanged since the last ice age.
Diatoms are just one example of algae, and this fact doesn’t change what we think about algae in general. We need to weaken the connection between ferrous material and algae.
B
Computer models suggest that a large increase in ferrous material today could greatly promote the growth of oceanic algae.
If anything, this supports the scientist’s argument. We want to weaken this same connection.
C
The dust found in the air bubbles trapped in Antarctic ice contained other minerals in addition to the ferrous material.
Were these other minerals the cause of the algae? As it is, we don’t know enough about them to say they weaken the argument.
D
Sediment from the ocean floor near Antarctica reflects no increase, during the last ice age, in the rate at which the shells that diatoms leave when they die accumulated.
At least one type of algae didn’t actually increase at all in Antarctica during the period in question. This suggests the ferrous material wasn’t causing algae growth.
E
Algae that currently grow in the oceans near Antarctica do not appear to be harmed by even a large increase in exposure to ferrous material.
The scientist claims that ferrous material causes algae growth. This doesn’t weaken that claim, and in fact defends against a possible weakener—that too much ferrous material is harmful to algae.
Summary
The argument concludes that modifying all cars to prevent them from exceeding the speed limit would prevent most car accidents. This is supported by the claim that exceeding the speed limit is a significant factor in most accidents.
Notable Assumptions
The argument’s conclusion aims at preventing most accidents by preventing speeding, which is a “significant factor” in most accidents. This requires the assumption that speeding actually determines whether most accidents will happen—in other words, that there aren’t other significant factors that would still lead most accidents to happen.
It also requires assuming that preventing speeding would not cause so many additional accidents that the total number of accidents would stay high.
It also requires assuming that preventing speeding would not cause so many additional accidents that the total number of accidents would stay high.
A
A person need not be a trained mechanic to install the device properly.
The argument merely claims that installing these devices in all cars would prevent most accidents. How easy it is to install the devices, or who is able to do it, is irrelevant.
B
Most accidents are caused by inexperienced drivers.
The argument’s claim that preventing speeding would prevent most arguments doesn’t depend on who is causing accidents, so this isn’t necessary to assume.
C
A driver seldom needs to exceed the speed limit to avoid an accident when none of the other drivers involved are violating the speed limit.
If we negate this, meaning that drivers would frequently need to speed in order to avoid otherwise non-speeding accidents, that would be one way that installing the device would cause more accidents. And the argument relies on that not being the case!
D
Most drivers who exceed the speed limit do so unintentionally.
The argument that preventing speeding would prevent most accidents doesn’t rely on the intention behind speeding. That makes this irrelevant.
E
Even if the fines for speed-limit violations were increased, the number of such violations would still not be reduced.
The argument never claims that installing this device is the only way to reduce or prevent speeding, so this is irrelevant.
Summarize Argument
The director of concludes that a consultant’s recommendations for improving productivity by giving employees work that they enjoy and are good at would violate company policy. This is because the consultant says her recommendations will “fully exploit” the company’s workforce resources, and the company’s policy is not to exploit its workers.
Identify and Describe Flaw
This is a cookie-cutter equivocation flaw: the director wrongly takes the term “exploit” to be the same between two different uses. When the consultant talks about “exploiting” the resources of the company, she’s just talking about making the best use of employees’ abilities. The company policy not to “exploit” workers refers to treating employees unfairly, which wouldn’t result from the consultant’s recommendations.
A
failing to distinguish two distinct senses of a key term
The director doesn’t distinguish between two uses of “exploit” that have different meanings in their respective contexts. The director wrongly takes the consultant’s use of “exploit” (optimize resources) to be the same as the company policy’s use of “exploit” (treat unfairly).
B
attempting to defend an action on the ground that it is frequently carried out
The director doesn’t try to defend any action in this argument. There also isn’t any example discussed of an action that is frequently carried out.
C
defining a term by pointing to an atypical example of something to which the term applies
The director doesn’t define any terms here. In fact, the flaw in the director’s argument is a failure to recognize two distinct definitions of the same term, “exploit”.
D
drawing a conclusion that simply restates one of the premises of the argument
The director concludes that the consultant’s recommendation would violate company policy, which is not a premise used earlier in the argument.
E
calling something by a less offensive term than the term that is usually used to name that thing
This argument doesn’t deal with offensive terminology, and the director doesn’t replace any usual terms with different ones.
Summary
The author concludes that we can’t be sure the recent decline in certain amphibian populations is due to industrial pollution.
Why?
Because most amphibian species populations vary greatly from year to year due to natural weather variations.
Why?
Because most amphibian species populations vary greatly from year to year due to natural weather variations.
Notable Assumptions
The author assumes that the decline in certain amphibian populations is within the range that could be explained by natural weather variations.
The author also assumes that the certain amphibian populations we’re talking about are among the “most” species whose populations are known to vary greatly due to weather variation.
The author also assumes that the certain amphibian populations we’re talking about are among the “most” species whose populations are known to vary greatly due to weather variation.
A
The amphibian species whose population declines have been attributed by many scientists to industrial pollution are not known to be among those species whose populations do not vary greatly as a result of natural variations in the weather.
Necessary, because if this were not true — if the amphibian species we’re talking about ARE known to be among the species whose populations don’t vary due to weather — then the author’s premise does not support the conclusion. If (A) were negated, natural weather variations wouldn’t be relevant to the amphibian species’ decline anymore.
B
The variations in amphibian species’ populations that result from natural variations in the weather are not always as large as the amphibian population declines that scientists have attributed to industrial pollution.
Not necessary, because the negation of (B) helps the author’s argument. If the variations in populations that result from weather variation ARE always as large as the population declines that others attribute to pollution, then that’s even more reason to think natural weather variations could be the explanation for the population decline.
C
Either industrial pollution or natural variations in the weather, but not both, caused the amphibian population declines that scientists have attributed to industrial pollution.
Not necessary, because the author never actually takes a position on what caused or didn’t cause the decline in the population. The author’s just saying that we can’t be sure it’s industrial pollution. But it might be industrial pollution, weather, or something else entirely that is the true cause.
D
If industrial pollution were reduced, the decline in certain amphibian populations would be reversed, and if industrial pollution increases, the decline in certain amphibian populations will be exacerbated.
Not necessary, because the author’s not committed to industrial pollution as the cause of the species’ population decline. The author doesn’t have to think industrial pollution has anything to do with the decline.
E
If industrial pollution is severe, it can create more variations in the weather than would occur naturally.
Not necessary, because the author never suggests any causal connection between pollution and weather variation.
Columnist: On average, about 70 percent of the profit from tourism in developing countries goes to foreign owners of tourist businesses. In general, as a country becomes a more established tourist destination, the proportion of revenues exported in this way increases. However, tourists can counteract this effect by obtaining accommodations and other services directly from local people.
Summary
Columnist: On average, 70% of tourism profits in developing countries go to foreign business owners. As a country becomes a more popular tourist spot, this percentage tends to rise. However, tourists can counteract this effect by getting accommodations and other services directly from locals.
Strongly Supported Conclusions
In at least some situations, tourists are able to influence local economies.
In some developing countries that are established tourist destinations, most tourism profits go to foreign owners of tourist businesses.
A
Tourists in a developing nation should obtain accommodations and other services directly from local people if most of the profits from tourism in that nation go to foreign owners of tourist businesses.
Unsupported. The stimulus tells us that tourists can counteract the profits of foreign business owners by obtaining services from local people, but it does not provide a value judgement as to what tourists should or should not do.
B
In at least some of the developing countries that are most established as tourist destinations, most of the profits from tourism go to foreign owners of tourist businesses.
Strongly supported. An average of 70% of tourism profits go to foreign business owners. This increases when a country is a more established tourism spot. So, in some of the developing countries that are most established as tourist spots, most tourism profits go to those owners.
C
In at least some developing countries, tourists obtain most of their accommodations and other services directly from local people.
Unsupported. The stimulus tells us that tourists can obtain accommodations directly from local people, but we do not know whether tourists actually obtain these things from local people in any developing countries.
D
In general, as a developing country becomes a more established tourist destination, local people become progressively poorer.
Unsupported. The stimulus tells us that a large percentage of tourism profits are exported, but there is also a percentage that remains in the country. We do not know that local people become progressively poorer as tourism becomes more established.
E
Tourists who obtain accommodations and other services directly from local people do not contribute in any way to the profits of foreign owners of tourist businesses.
Unsupported. Tourists who obtain accommodations and other services directly from local people may help to counteract the rising profits of foreign business owners, but we do not have enough information to conclude that they do not contribute in any way to those profits.