Modest amounts of exercise can produce a dramatic improvement in cardiovascular health. One should exercise most days of the week, but one need only do the equivalent of half an hour of brisk walking on those days to obtain cardiovascular health benefits. More vigorous exercise is more effective, but a strenuous workout is not absolutely necessary.

Summary

Modest amounts of exercise can greatly improve heart health. You should exercise most days, but the equivalent of just 30 minutes of brisk walking on those days is enough to see benefits. More intense exercise works better, but a hard workout isn’t required.

Strongly Supported Conclusions

Because they’re more effective than modest exercise, strenuous workouts most days of the week can also dramatically improve heart health.

Improving heart health does not require strenuous exercise or time-consuming workouts.

A
Having a strenuous workout most days of the week can produce a dramatic improvement in cardiovascular health.

Strongly supported. Modest amounts of exercise most days of the week can dramatically improve heart health. Strenuous exercise is more effective than modest exercise. So, having a strenuous workout most days of the week can dramatically improve heart health.

B
Doing the equivalent of an hour of brisk walking two or three times a week generally produces dramatic improvements in cardiovascular health.

Unsupported. We’re told that doing the equivalent of 30 minutes of brisk walking most days of the week (at least 4 days) can improve heart health. We don’t know that doing the equivalent of an hour of brisk walking 2-3 times a week could produce the same improvements.

C
It is possible to obtain at least as great an improvement in cardiovascular health from doing the equivalent of half an hour of brisk walking most days of the week as from having a strenuous workout most days of the week.

Anti-supported. We’re told that strenuous exercise is more effective than modest exercise. So we cannot conclude that it’s possible to obtain at least as great an improvement in heart health from modest exercise as from strenuous exercise.

D
Aside from exercise, there is no way of improving one’s cardiovascular health.

Unsupported. We know that exercise can improve cardiovascular health, but we do not know that it’s the only way to improve cardiovascular health.

E
To obtain a dramatic improvement in one’s cardiovascular health, one must exercise strenuously at least occasionally.

Anti-supported. We’re told that modest amounts of exercise can produce a dramatic improvement in cardiovascular health and that although more vigorous exercise is more effective, “a strenuous workout is not absolutely necessary.”


32 comments

Anthropologist: In an experiment, two groups of undergraduates were taught how to create one of the types of stone tools that the Neanderthals made in prehistoric times. One group was taught using both demonstrations and elaborate verbal explanations, whereas the other group learned by silent example alone. The two groups showed a significant difference neither in the speed with which they acquired the toolmaking skills nor in the level of proficiency they reached. This shows that Neanderthals could just as well have created their sophisticated tools even if they had no language.

Summarize Argument
The anthropologist concludes that Neanderthals could’ve created tools without language. She bases this on a study showing that university students were as capable of making one type of prehistoric stone tool when they learned by silent example as when they learned by verbal instruction.

Notable Assumptions
The anthropologist assumes that the stone tools Neanderthals made were no more sophisticated than those that the undergraduates made. If the Neanderthals consistently made far more sophisticated tools, then no conclusion can be drawn from the study about whether or not language was necessary for Neanderthal tool-building.

A
Apart from the sophistication of their stone tools, there is a great deal of evidence suggesting that Neanderthals possessed some form of language.
We don’t care about evidence that tells us Neanderthals had language. We’re interested in whether their tools prove they must’ve had language.
B
The students who were taught with verbal explanations were allowed to discuss the toolmaking techniques among themselves, whereas the students who learned by silent example were not.
Both groups created the same tools. This doesn’t further differentiate them in any meaningful way.
C
The tools that the undergraduates were taught to make were much simpler and easier to make than most types of tools created by Neanderthals.
Sure, simple tools can be made without language. But Neanderthals also made many types of sophisticated tools. We don’t know if they needed language to make those.
D
The instructor who taught the group of students who learned by silent example alone was much less proficient at making the stone tools than was the instructor who taught the other group of students.
Like (B), both groups created the same tools. This doesn’t further differentiate them in any meaningful way.
E
The tools created by Neanderthals were much less sophisticated than the tools created by anatomically modern humans who almost certainly possessed language and lived at the same time as the Neanderthals.
We don’t care about other humanoids. We need to know whether we can draw conclusions about Neanderthals and language based on the tools they made.

6 comments

In a recent field study of prairie plants, the more plant species a prairie plot had, the more vigorously the plants grew and the better the soil retained nutrients. Thus, having more plant species improves a prairie’s ability to support plant life.

Summarize Argument: Phenomenon-Hypothesis
The author concludes that having more plant species causes a prairie to be better able to support plant life. This is based on a study of praire plants, which found a correlation between the number of plant species on a prairie plot and how well plants grew on the plot.

Identify and Describe Flaw
The author assumes the correlation between plant species and how well plants grew is explained by the number of species causing more vigorous growth. This overlooks alternate explanations. For example, maybe the relationship is reversed. Better soil and ability to support plant life might cause a greater number of species to flourish on the plot. Or maybe there’s a third factor that causes both better ability to support plant life and greater numbers of species.

A
infers of two correlated phenomena, X and Y, that X causes Y without considering whether Y causes X
The author infers that more plant species (X) causes greater ability to support plant life (Y) based on the correlation observed in the study between more plant species (X) and greater ability to support plant life (Y).
B
fails to describe the mechanism by which productivity is supposedly increased
The author doesn’t need to describe the causal mechanism. A causal claim can be supported by evidence, even if the author never describes the mechanism underlying the causal relationship.
C
takes for granted that the characteristics of one prairie plot could reveal something about the characteristics of other prairie plots
There’s nothing flawed about thinking that one prairie plot can reveal something about others; if that plot is similar to other plots, it can still reveal something about others. Also, the study evaluated multiple plots; it wasn’t based on just one plot.
D
bases a general conclusion on data that is likely to be unrepresentative
We have no reason to think that the plots involved in the study are likely to be unrepresentative of prairie plots.
E
takes an increase in number to indicate an increase in proportion
The study showed that the more plant species in a plot, the better the plants grew. This doesn’t tell us there was an “increase” in plant species in any plot. In addition, the argument never asserts anything about the proportion of plant species or plants.

5 comments

Editorialist: The city council is considering increasing the amount of air traffic allowed at the airport beyond its original design capacity. Several council members say that this increase would not decrease safety as it would be accompanied by the purchase of the latest safety technology. But in fact it would decrease safety. Numerous studies conducted 30 years ago show that safety was reduced at every airport where the permitted level of traffic was increased beyond the airport’s original design capacity, even when those airports made use of the latest safety technology.

Summarize Argument
The author concludes that increasing air traffic allowed at the airport beyond its original design capacity would decrease safety. This is based on studies done 30 years ago, which showed that safety was reduced at every airport where the permitted air traffic was increased beyond the airport’s original design capacity, even when those airports made use of the latest (as of 30 years ago) safety technology.

Identify and Describe Flaw
The author overlooks the possibility that the latest safety technology today is significantly more advanced than the latest safety technology as of 30 years ago. In other words, perhaps the results obtained in the studies from 30 years ago aren’t very relevant to what would happen as a result of increased air traffic today, due to better technology.

A
The argument draws a conclusion on the basis of a general statement that has in turn been inferred from a very limited number of particular instances.
The argument is based on numerous studies. We have no reason to think that these numerous studies are only a “very limited number of particular instances.”
B
The argument fails to consider the possibility that whether an airport can allow more air traffic than it was originally designed for without reducing safety depends largely on what the latest technology is.
(B) points out that the latest technology (as of today) might allow for more air traffic safely, even though older technology didn’t. What was the “latest” technology 30 years ago isn’t necessarily the latest technology today.
C
The argument fails to consider the possibility that the city council members who support the increase are aware of the studies that were conducted 30 years ago.
The argument’s reasoning has nothing to do with the city council members. The argument is based on the numerous studies conducted 30 years ago. Whether people who disagree with the author are aware of those studies doesn’t affect the reasoning.
D
The argument confuses an absence of evidence for the claim that the airport can safely permit air traffic in excess of its original design capacity with the existence of evidence against this claim.
The argument’s reasoning doesn’t point out that there’s a lack of evidence for the view that airports can safely increase air traffic. The reasoning is based on studies from 30 years ago.
E
The argument fails to consider that a slight increase in safety risks might be acceptable if it yields overriding benefits of another kind.
The author doesn’t conclude that we should increase air traffic. So whether risks are acceptable or not are irrelevant. The conclusion is simply that increasing air traffic beyond original capacity will decrease safety.

9 comments