The symptoms of hepatitis A appear no earlier than 60 days after a person has been infected. In a test of a hepatitis A vaccine, 50 people received the vaccine and 50 people received a harmless placebo. Although some people from each group eventually exhibited symptoms of hepatitis A, the vaccine as used in the test is completely effective in preventing infection with the hepatitis A virus.

"Surprising" Phenomenon
Why did people who received the hepatitis A vaccine exhibit symptoms of hepatitis A?

Objective
A hypothesis resolving this discrepancy must reveal new information about the group who received the vaccine. It should either indicate their infection with hepatitis A prior to inoculation or distinguish between the hepatitis A virus and the symptoms it causes.

A
The placebo did not produce any side effects that resembled any of the symptoms of hepatitis A.
This does not imply that the vaccine did produce such side effects. It refers to placebo recipients only, and does not address the discrepancy, which involves only vaccine recipients.
B
More members of the group that had received the placebo recognized their symptoms as symptoms of hepatitis A than did members of the group that had received the vaccine.
This is irrelevant information. There is no indication that participants self-reported their symptoms, so this difference in attribution between the groups would not have affected the study.
C
The people who received the placebo were in better overall physical condition than were the people who received the vaccine.
This does not explain why people who received the vaccine developed hepatitis A symptoms. The discrepancy is not between the two groups, but between the vaccine's complete effectiveness and the hepatitis A symptoms among the people who received it.
D
The vaccinated people who exhibited symptoms of hepatitis A were infected with the hepatitis A virus before being vaccinated.
This resolves the apparent paradox by explaining that vaccine recipients were infected prior to inoculation. It is consistent because the author gives no information about the vaccine's effect on patients already infected with hepatitis A.
E
Of the people who developed symptoms of hepatitis A, those who received the vaccine recovered more quickly, on average, than those who did not.
This does not explain how vaccine recipients developed symptoms in the first place. If the vaccine is completely effective, patients who received it should not have contracted hepatitis A.

17 comments

The Board of Trustees of the Federici Art Museum has decided to sell some works from its collection in order to raise the funds necessary to refurbish its galleries. Although this may seem like a drastic remedy, the curator has long maintained that among the paintings that the late Ms. Federici collected for the museum were several unsuccessful immature works by Renoir and Cézanne that should be sold because they are of inferior quality and so add nothing to the overall quality of the museum’s collection. Hence, the board’s action will not detract from the quality of the museum’s collection.

Summarize Argument
The author concludes that the board’s decision to sell some works will not detract from the quality of the museum’s collection.

Notable Assumptions
The author assumes that the curator is correct about the quality of the works and how they contribute to the museum’s overall quality. This means that the author is taking the curator as an authority on the issues, and thus appealing to authority in order to draw his conclusion. The author, following the curator, assumes that works of inferior quality can’t contribute to the overall quality of a museum.

A
The directors of an art museum can generally raise funds for refurbishing the building in which the museum’s collection is housed by means other than selling part of its collection.
Whether or not the art museum could’ve raised funds some other way is irrelevant. We need to weaken the argument—that these paintings are of inferior quality and can therefore be sold.
B
The quality of an art collection is determined not just by the quality of its paintings, but by what its collection demonstrates about the development of the artistic talent and ideas of the artists represented.
While these immature works are not high-quality, they represent integral stages in Renoir and Cézanne’s artistic development. The quality of the paintings might be mitigated by their importance to the collection as a whole, meaning the gallery has a reason not to sell them.
C
The immature works by Renoir and Cézanne that were purchased by Ms. Federici were at that time thought by some critics to be unimportant juvenile works.
It doesn’t matter what critics thought at the time these paintings were purchased. We need to know whether or not their quality means the gallery should sell them today.
D
Those people who speculate in art by purchasing artworks merely to sell them at much higher prices welcome inflation in the art market, but curators of art museums regret the inflation in the art market.
This is irrelevant. We don’t care what curators think about inflation.
E
The best work of a great artist demands much higher prices in the art market than the worst work of that same artist.
We don’t care how much money the gallery will get for these works. We need to know if their quality means the gallery should sell them.

31 comments

The only motives that influence all human actions arise from self-interest. It is clear, therefore, that self-interest is the chief influence on human action.

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.

33 comments