Summarize Argument: Counter-Position
The author concludes that the 1/20,000 figure is less reliable than the 1 in 2 million figure concerning the chance a commercial flight will stray off course when landing. This is based on the fact that the 1/20,000 figure is based on a partial review of air traffic ccontrol tapes, while the 1 in 2 mill. figure is based on a study of flight reports of pilots for all commercial flights.
Identify and Describe Flaw
The author doesn’t provide any compelling reason to think a partial review of air traffic control tapes is any less reliable than a review of flight reports for all flights. The tapes might contain more accurate information than the flight reports, even if the tapes don’t involve a review of all flights.
A
The argument presumes, without providing justification, that building runways closer together will encourage pilots to be more cautious while landing.
The argument concerns which statistic is more reliable. The impact of building runways closer together on pilots’ level of caution doesn’t bear on which statistic is more reliable.
B
The argument overlooks the fact that those who make mistakes are often unreliable sources of information about those mistakes.
The flight reports are “required of pilots”; this indicates the pilots are the sources of the reports. (B) points out that this information can be unreliable, because pilots who stray off course — which is a mistake — might not report that mistake.
C
The argument questions the integrity of those who are opposed to allowing runways to be built closer together.
The argument doesn’t question the integrity of any individuals. It relies on premises concerning the basis of the two statistics. Neither of these statistics comes from those who are against closer runways.
D
The argument presumes, without providing justification, that the air traffic control tapes studied do not provide accurate information concerning specific flights.
The author doesn’t assert that the tapes cannot provide accurate information. The author’s complaint is that the review of those tapes is only “partial.” So the author is open to the possibility that information in the tapes is accurate; it may be accurate, but incomplete.
E
The argument infers from a lack of conclusive evidence supporting the higher number’s accuracy that it must be inaccurate.
The author doesn’t conclude that the 1/20,000 figure is inaccurate, only that it’s less reliable. Also, the basis of the conclusion is not a lack of conclusive evidence for the 1/20,000 figure. The basis is a comparison of the sources of the two figures.
Merriweather: It isn’t that the school paid more for each computer than it was worth, but that the computers that were purchased were much more elaborate than they needed to be.
Speaker 1 Summary
Sanchez says that the school did not spend too much money on some new computers. How do we know? Because the computers weren’t actually as expensive as many people believe. According to Sanchez, this makes their cost reasonable.
Speaker 2 Summary
Merriweather’s implied conclusion is that the school did spend too much on computers, even though they only paid what the computers were worth. How can this be? Because the school bought fancier computers than they needed, thus ultimately still overspending.
Objective
We want to find a point of disagreement. Sanchez and Merriweather disagree about whether the school spend too much on the new computers.
A
needed sixteen new computers
Like (B), neither speaker expresses an opinion about this. Whether or not the school needed new computers in the first place is not discusses by either Sanchez or Merriweather.
B
purchased more computers than it should have
Like (A), neither Sanchez nor Merriweather talks about this. The question of how many computers the school actually needed just doesn’t come up, so we can’t say either speaker states an opinion.
C
spent more in purchasing the sixteen computers than it should have
Sanchez disagrees and Merriweather agrees, so this is the point of disagreement. Sanchez explicitly states that the school did not overspend on the computers. Merriweather explains that the computers were fancier than necessary, thus implying that the school did spend too much.
D
paid more for each computer than it was worth
Both speakers disagree with this statement, meaning they are in agreement with one another. Sanchez takes the position that the school didn’t pay too much, and even Merriweather concedes that the school paid what each computer was worth.
E
has been harshly criticized for purchasing the sixteen computers
Neither Sanchez nor Merriweather discusses whether and how much people have criticized the school for this purchase, so we cannot say that either speaker has an opinion.
A
takes a sufficient condition for a state of affairs to be a necessary condition for it
The purpose of laws being happiness is sufficient to have a basis for criticizing laws. But the author thinks this purpose is necessary for having a basis to criticize.
B
infers a causal relationship from the mere presence of a correlation
The evidence doesn’t present a correlation.
C
trades on the use of a term in one sense in a premise and in a different sense in the conclusion
The author doesn’t use any term in two ways. “Legitimacy” means legitimacy throughout the argument. “Laws” mean laws throughout the argument.
D
draws a conclusion about how the world actually is on the basis of claims about how it should be
The evidence does not assert anything about how the world “should” be.
E
infers that because a set of things has a certain property, each member of that set has the property
The argument doesn’t commit a whole-to-part fallacy. There is no whole presented in the premises, and no individual parts of a whole presented in the conclusion.
"Surprising" Phenomenon
Why did the moose herd continue to grow while the wolves that were supposed to prey on them prospered?
Objective
The right answer will describe some aspect of the environment, the wolves’ behavior, or the moose’s behavior that caused the wolves’ introduction to have little or no negative impact on the moose population’s growth.
A
The presence of wolves in an area tends to discourage other predators from moving into the area.
This doesn’t help. Even if other predators did not move into the area after the wolves were introduced, the wolves themselves are predators, and we would expect the moose herd’s growth to have been impacted by their presence.
B
Attempts to control moose populations in other national parks by introducing predators have also been unsuccessful.
This doesn’t help. We’re looking for the reason why this particular attempt to control the moose population did not work, not other examples of failed attempts.
C
Wolves often kill moose weakened by diseases that probably would have spread to other moose.
This is what we need. If wolves often kill sick moose, they’re protecting the healthy moose from contracting illnesses which might have otherwise killed off more moose and slowed the population’s growth. Also, the diseased moose the wolves kill presumably would have died anyway.
D
Healthy moose generally consume more vegetation than do those that are diseased or injured.
This is irrelevant. We’re not looking for information about how much vegetation healthy vs. diseased or injured moose eat, and this answer choice tells us nothing about what happened when the wolves were introduced.
E
Moose that are too old to breed are just as likely to die of natural causes as of attack by wolves.
We’re not interested in moose that are too old to breed, because the factor we’re examining is population growth. Furthermore, even if older moose are just as likely to die of natural causes, wolf attacks would still presumably kill additional moose, both older and younger.