Summary
Ten years ago, stricter regulations on power plant emissions were imposed.
If those regulations had been followed, the level of sulfur dioxide in the atmosphere would have decreased.
The level of sulfur dioxide in the atmosphere has increased over the last ten years.
If those regulations had been followed, the level of sulfur dioxide in the atmosphere would have decreased.
The level of sulfur dioxide in the atmosphere has increased over the last ten years.
Very Strongly Supported Conclusions
The emissions regulations have not been followed.
A
If current regulations on emissions from coal-burning power plants are not followed from now on, then the level of sulfur dioxide in the atmosphere will continue to increase.
Unsupported. The level of sulfur dioxide increased because the regulations were not followed, but we don’t know what might happen if the regulations are not followed from now. Sulfur dioxide might continue to increase, or it might level out, or something else might reduce it.
B
There have been violations of the regulations on emissions from coal-burning power plants that were imposed ten years ago.
Very strongly supported. If the regulations had been followed, the level of sulfur dioxide in the atmosphere would have decreased. But the level of sulfur dioxide has increased, so the regulations must not have been fully followed.
C
If the regulations on emissions from coal-burning power plants are made even stronger, the level of sulfur dioxide in the atmosphere still will not decrease.
Unsupported. The stimulus doesn’t tell us anything about what might happen if regulations are made stronger. We only know that if the original regulations had been followed, then sulfur dioxide levels would have decreased.
D
Emissions from coal-burning power plants are one of the main sources of air pollution.
Unsupported. Power point emissions caused an increase in the level of sulfur dioxide in the atmosphere, but we don’t know that they’re one of the main sources of air pollution.
E
Government regulations will never reduce the level of sulfur dioxide in the atmosphere.
Unsupported. The regulations imposed ten years ago didn’t successfully reduce the level of sulfur dioxide in the atmosphere, but that doesn’t mean that government regulations will never reduce it.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that the book Horatio wants must have been either misplaced or stolen. He supports this by saying that the book is missing from its place on the shelf and no one in the library is using it. It also isn’t checked out to a borrower, awaiting shelving, or part of a special display.
Describe Method of Reasoning
The author supports his hypothesis that the book in question was either misplaced or stolen by eliminating alternative explanations for its absence from the shelf.
A
An observation about one object is used as a basis for a general conclusion regarding the status of similar objects.
The author does use an observation about the book Horatio wants, but he uses it to draw a specific conclusion about that same book, not a general conclusion about similar books.
B
A deficiency in a system is isolated by arguing that the system failed to control one of the objects that it was intended to control.
The author doesn't claim that the library system is deficient or that it failed to control the book. He simply argues that, since the book is missing and other explanations for its absence have been ruled out, it must have been misplaced or stolen.
C
A conclusion about a particular object is rebutted by observing that a generalization that applies to most such objects does not apply to the object in question.
The author never rebuts any conclusion about the book; he draws a conclusion by eliminating alternative explanations. He also doesn’t apply any generalizations about most books to the particular book that Horatio wants.
D
A generalization is rejected by showing that it fails to hold in one particular instance.
The author never rejects a generalization, nor does he show that a generalization fails to hold in the particular instance of the missing book. Instead, he supports a particular conclusion about the book.
E
The conclusion is supported by ruling out other possible explanations of an observed fact.
The author supports his conclusion by ruling out other possible explanations of the book's absence. Since no one is using it, it isn't checked out, waiting to be shelved, or part of a display, he concludes that it must have been misplaced or stolen.
Summarize Argument: Phenomenon-Hypothesis
Jim concludes that a substance contains iron because it’s attracted to a magnet, and iron is a material that’s attracted to magnets.
Identify and Describe Flaw
This is a cookie-cutter example of an argument mistaking a sufficient condition for a necessary condition. Jim treats “containing iron” as though it were a necessary condition for being magnetic, even though it’s only sufficient. In other words, he ignores the possibility that the substance contains a magnetic material other than iron.
A
iron sometimes fails to be attracted to magnets
This possibility is irrelevant because the iron was attracted to the magnet in this case.
B
iron is attracted to other objects besides magnets
The argument is only concerned with whether being attracted to a magnet is enough to prove that a substance contains iron. Whether iron is also attracted to other objects has no bearing on that issue.
C
the magnet needed to be oriented in a certain way
Even if this were a requirement, the magnet would have to have been oriented correctly since it attracted the substance in this case.
D
magnets attract substances other than iron
This possibility undermines the conclusion because it means that the substance could be attracted to the magnet because it contains some magnetic material other than iron.
E
some magnets attract iron more strongly than others
The argument is only concerned with whether the magnet attracts the substance or not; the degree to which it attracts it is irrelevant.