Mayor: To keep our neighborhoods clean, every street in town will be swept at least once a month. If a neighborhood needs more frequent sweepings, due to excessive dirt from major construction for example, that neighborhood will be qualified for interim sweepings. All requests for interim sweepings from qualified neighborhoods will be satisfied immediately.
Summary
Every street in town will be swept at least once a month.
If a neighborhood needs to be swept more frequently than once a month, that neighborhood will be qualified for interim sweepings.
All requests for interim sweepings from qualified neighborhoods will immediately be satisfied.
Notable Valid Inferences
If a qualified neighborhood requests interim sweepings, that neighborhood’s streets will be swept more than once a month.
If a neighborhood is excessively dirty from major construction, that neighborhood will be qualified to receive sweepings more frequently than once a month.
If a neighborhood with excessive dirt from major construction requests interim sweepings, that neighborhood’s streets will be swept more than once a month.
A
All neighborhoods in which construction is under way are qualified neighborhoods.
Could be false. The stimulus states that a neighborhood is qualified if there is excessive dirt from major construction, not merely if there is any type of construction at all. Maybe minor construction does not lead to excessive dirt!
B
All qualified neighborhoods will get their streets swept more than once a month.
Could be false. The stimulus does not say that qualified neighborhoods that do not request interim sweepings will receive such sweepings (but it also doesn’t say that they won’t). Maybe some qualified neighborhoods will not submit a request and thus will only be swept monthly!
C
No street will be swept more than once a month unless it is located in a qualified neighborhood.
Could be false. The stimulus doesn’t state that being a qualified neighborhood is the only way to receive more frequent sweepings. As far as we know, “qualified neighborhood that requests interim sweepings” is a sufficient, not necessary, condition of receiving interim sweepings.
D
A qualified neighborhood that requests an interim sweeping will have its streets swept more than once a month.
Must be true. If a neighborhood is qualified for interim sweepings and it requests such sweepings, that request will be satisfied. In other words, that neighborhood will have its streets swept more than once a month!
E
No street in an unqualified neighborhood will be swept more than once a month even if the neighborhood requests it.
Could be false. The stimulus doesn’t state that being a qualified neighborhood is the only way to receive more frequent sweepings. As far as we know, “qualified neighborhood that requests interim sweepings” is a sufficient, not necessary, condition of receiving interim sweepings.
Journalist: It is unethical for journalists to lie—to say something untrue with the purpose of deceiving the listener—to get a story. However, journalists commonly withhold relevant information in interviews in order to elicit new information. Some argue that this, like lying, is intentional deception and therefore unethical. However, this argument fails to recognize the distinction between failing to prevent a false belief and actively encouraging one. Lying is unethical because it actively encourages a false belief.
Summarize Argument: Counter-Position
The journalist implicitly concludes that some people’s argument— that journalists are acting unethically when they withhold information to elicit new information because this practice is like lying— should be rejected. She supports this by saying that this argument overlooks the distinction between not preventing a false belief and actively encouraging a false belief, and that lying is unethical for the latter reason.
Describe Method of Reasoning
The journalist counters others’ argument by highlighting a key difference between lying and withholding information. She argues that this distinction invalidates their comparison and thus also invalidates their conclusion.
A
pointing out a difference between the two cases being compared in order to show that a conclusion based on their similarities should not be drawn
The journalist points out a difference between the two cases being compared: lying actively encourages a false belief, while withholding information simply doesn’t prevent a false belief. She uses this to show that a conclusion based on the cases’ similarities shouldn't be drawn.
B
defending what the journalist considers a controversial distinction by offering an example of a clear instance of it
The journalist’s conclusion isn’t about defending the distinction between lying and withholding information. Instead, she uses this distinction to counter others’ argument. Also, she never claims that the distinction is controversial, nor does she offer an example of it.
C
defining a concept and then showing that under this definition the concept applies to all of the cases under discussion
The journalist defines lying, but she claims that lying does not apply to all the cases under discussion. Specifically, it doesn’t apply to journalists who withhold information in interviews in order to elicit new information.
D
appealing to a counterexample to undermine an ethical principle that supports an argument the journalist is trying to refute
The journalist does refute an argument, but she doesn’t do so by appealing to a counterexample to undermine the ethical principle of lying. She accepts that it’s unethical for journalists to lie to get a story; she just disagrees that withholding information is like lying.
E
clarifying and defending a moral principle by comparing a case in which it applies to one in which it does not apply
The journalist compares a case in which the moral principle of lying applies (journalists lying to get a story) to one in which it doesn’t apply (journalists withholding information). However, she doesn’t do so to defend the moral principle, but to undermine others’ argument.
Given the shape of the hip and foot bones of the Kodiak bear, it has been determined that standing and walking upright is completely natural behavior for these bears. Thus, walking on hind legs is instinctive and not a learned behavior of the Kodiak.
Summarize Argument
The author concludes that walking on hind legs is instinctive for Kodiak bears and not a learned behavior. He supports this by saying that their bone structure makes walking upright completely natural for them.
Identify and Describe Flaw
The author assumes that because it’s instinctive for Kodiak bears, walking on hind legs is not a learned behavior. He ignores the possibility that walking on hind legs might be both an instinctive and a learned behavior.
A
The argument incorrectly generalizes from the behavior of a few bears in support of its conclusion.
This is the cookie-cutter flaw of hasty generalization, where the argument draws a broad conclusion based on too little evidence. The author doesn’t make this mistake; he draws a conclusion about the behavior of all Kodiaks based on a premise about the bones of all Kodiaks.
B
The argument fails to consider the possibility that walking on hind legs is the result of both learning and an innate capacity.
The author assumes that, because walking on hind legs is completely natural for Kodiak bears, it must not be a learned behavior. He fails to consider that it could be both an innate behavior due to the bears’ bone structure and also a learned behavior.
C
The word “behavior” illicitly changes meaning during the course of the argument.
This is the cookie-cutter flaw of equivocation, where the same term is used in different ways throughout the argument. The author doesn’t make this mistake; he uses the word “behavior” consistently and he clearly distinguished between “natural behavior” and “learned behavior.”
D
The argument presumes, without giving justification, that all behavior can be explained in one or both of only two ways.
The author isn’t addressing all behavior, only the bears’ behavior of walking on hind legs. Also, his mistake is that he assumes that walking on hind legs cannot be explained by both innate and learned behaviors.
E
The argument incorrectly appeals to the authority of science in order to support its conclusion.
The author relies on a scientific claim to support his conclusion, so his argument doesn’t incorrectly appeal to the authority of science.
A
Statistical information tends to obscure the characteristics of individuals.
B
Most people recognize that anecdotes tend to be about unrepresentative cases.
C
The more emotionally compelling an anecdote is, the more likely it is to change a person’s beliefs.
D
Statistical information is made more comprehensible when illustrated by anecdotes.
E
People tend to base their beliefs about other people on their emotional response to those people.
In 2005, paleontologist Mary Schweitzer made headlines when she reported finding preserved soft tissue in the bones of a Tyrannosaurus rex dinosaur. Analysis of the collagen proteins from the T. rex showed them to be similar to the collagen proteins in modern-day chickens. Schweitzer’s discovery therefore adds to the mountain of evidence that dinosaurs are closely related to birds.
Summarize Argument
The author concludes that dinosaurs are closely related to birds. This is due to, among other evidence, a paleontologist’s discovery: that T. rex had collagen proteins similar to those found in modern chickens.
Notable Assumptions
The author assumes that dinosaurs and chickens having similar collagen proteins adds to the evidence that dinosaurs and birds are similar. This means the author believes such collagen proteins aren’t common to a whole host of totally unrelated animals. This also means he believes two dissimilar animals won’t share collagen proteins.
A
How rare is it to find preserved soft tissue in the bones of a dinosaur?
Irrelevant. Whether it’s very rare or very common to find soft tissue in dinosaur bones tells us nothing about the author’s argument: that collagen proteins in dinosaurs tells us dinosaurs are closely related to birds.
B
Is there any evidence at all against the claim that dinosaurs are closely related to birds?
The author never claims that all evidence points to dinosaurs and birds being closely related. He simply claims that shared collagens adds to the “mountain of evidence” that dinosaurs and birds are related.
C
How likely is it for animals that are not closely related to each other to have similar collagen proteins?
If it’s highly likely for animals that aren’t closely related to share collagens, then shared collagens between dinosaurs and chickens wouldn’t signify a close relation—a weakener. If it’s highly unlikely, then collagens likely do signify a close relation—a strengthener.
D
Is it possible that T. rex is more closely related to modern-day chickens than to certain other types of dinosaurs?
Irrelevant. Even if it were “possible,” that wouldn’t tell us that dinosaurs and birds are in fact closely related.
E
Before Schweitzer’s discovery, did researchers suppose that the collagen proteins in T. rex and chickens might be similar?
We don’t care what researchers had hypothesized before this discovery. We’re interested in if the study constitutes evidence that dinosaurs and birds are closely related.