Sufficient vs Necessary
A development company has proposed building an airport near the city of Dalton. If the majority of Dalton’s residents favor the proposal, the airport will be built. However, it is unlikely that a majority of Dalton’s residents would favor the proposal, for most of them believe that the airport would create noise problems. Thus, it is unlikely that the airport will be built.
The reasoning in the argument is flawed in that the argument
A. treats a sufficient condition for the airport’s being built as a necessary condition
B. concludes that something must be true, because most people believe it to be true
C. concludes, on the basis that a certain event is unlikely to occur, that the event will not occur
D. fails to consider whether people living near Dalton would favor building the airport
E. overlooks the possibility that a new airport could benefit the local economy
A. treats a sufficient condition for the airport’s being built as a necessary condition
Several years ago, most of one country's large banks failed and were taken over by a government agency. The agency is now selling these banks, aiming to strengthen the banking system in the process. But the banking system will not be strengthened if the former owners of these banks buy them back. So the agency is unlikely to achieve its goal, since _______.
The conclusion of the argument is properly drawn if which one of the following completes the passage?
the agency may be unable to sell some of the banks
a single company could buy more than one of the banks
the country's overall economy is not much stronger than it was when the large banks failed
the banks sold by the agency will be financially weaker than the country's other banks for some time
all of the bidders for the banks are their former owners
all of the bidders for the banks are their former owners
The railway authority inspector who recently thoroughly checked the tracks testified that they were in good condition. Thus, since the inspector has no bias in the matter, we should be suspicious of the newspaper reporter's claim that the tracks are in poor condition.
The reasoning in the argument above is most similar to the reasoning in which one of the following arguments?
My pottery instructor says that making pottery will not cause repetitive-motion injuries if it is done properly. So I will probably not get such injuries, for whenever I do pottery I use the proper techniques that my instructor taught me.
Gardner, a noted paleontologist who has no vested interest in the case, assures us that the alleged dinosaur bones are not old enough to be from dinosaurs. So we should be skeptical of Penwick's claim to have found dinosaur bones, for Gardner inspected the bones carefully.
The engineer hired by the company that maintains the bridge has examined the bridge and declared it safe. This engineer is the only one who has given the bridge a close examination recently. Thus, we should consider the bridge safe.
The reporter who recently interviewed the prime minister said the prime minister appeared to be in poor health. But despite the fact that the reporter works for a paper with opposition leanings, we should accept that the prime minister is in poor health. After all, reporters won't let their bias affect them when the truth of their claims will eventually be discovered.
The snowblower salesperson claims that there will be above-average snowfall this winter, but because the salesperson is biased, we can discount that claim.
Gardner, a noted paleontologist who has no vested interest in the case, assures us that the alleged dinosaur bones are not old enough to be from dinosaurs. So we should be skeptical of Penwick's claim to have found dinosaur bones, for Gardner inspected the bones carefully.
Newspaper article: Recently discovered clay tablets from southern Egypt date to between 3300 and 3200 B.C. Though most of the tablets translated thus far are tax records, one of them appears to contain literary writing. Hence, these tablets challenge the widely held belief among historians that the Sumerian civilization in Mesopotamia was the first to create literature.
7. The argument in the newspaper article requires the assumption that
most of the recently discovered tablets that have not yet been translated contain literary writing
every civilization that has kept tax records has also kept other written records
historians generally believe that the Sumerians did not create literature earlier than 3300 B.C.
some historians are skeptical about the authenticity of the recently discovered tablets
the Sumerian civilization arose sometime between 3300 and 3200 B.C.
historians generally believe that the Sumerians did not create literature earlier than 3300 B.C.
The government's tax collection agency has not followed through on its plan, announced a year ago, to crack down on violations of corporate income tax law. Audits are the primary tool for detecting such violations, and over the past year, not a single audit of corporate income tax returns has been completed.
Which one of the following, if true, most weakens the argument?
The plan to crack down on violations of corporate income tax law is part of a broad campaign against corporate misconduct.
The number of personal income tax returns audited over the past year is greater than in previous years.
Most audits of corporate income tax returns do not reveal any significant violations.
It generally takes longer than one year to complete an audit of a corporate income tax return.
Over the last five years, fewer audits of corporate income tax returns have been completed than in the preceding five years.
It generally takes longer than one year to complete an audit of a corporate income tax return.
Fish with teeth specialized for scraping algae occur in both Flower Lake and Blue Lake. Some biologists argue that because such specialized characteristics are rare, fish species that have them should be expected to be closely related. If they are closely related, then the algae-scraping specialization evolved only once. But genetic tests show that the two algae-scraping species, although possibly related, are not closely related. Thus, the algae-scraping specialization evolved more than once.
The reasoning in the argument is flawed in that it
A. infers a cause merely from a correlation
B. infers that just because the evidence for a particular claim has not yet been confirmed, that claim is false
C. takes a sufficient condition as a necessary one
D. infers merely because something was likely to occur that it did occur
E. appeals to the authority of biologists who may not be representative of all biologists with expertise in the relevant area
C. takes a sufficient condition as a necessary one
Secondary school students achieve broad mastery of the curriculum if they are taught with methods appropriate to their learning styles and they devote significant effort to their studies. Thus, if such broad mastery is not achieved by the students in a particular secondary school, those students are not being taught with methods appropriate to their learning styles.
The conclusion can be properly drawn if which one of the following is assumed?
As long as secondary school students are taught with methods appropriate to their learning styles, they will devote significant effort to their studies.
Even if secondary school students are taught with methods appropriate to their learning styles, they will not achieve broad mastery of the curriculum if they do not devote significant effort to their studies.
Secondary school students do not achieve broad mastery of the curriculum if they are not taught with methods appropriate to their learning styles.
Teaching secondary school students with methods appropriate to their learning styles does not always result in broad mastery of the curriculum by those students.
Secondary school students who devote significant effort to their studies do not always achieve broad mastery of the curriculum.
As long as secondary school students are taught with methods appropriate to their learning styles, they will devote significant effort to their studies.
Party X has recently been accused by its opposition, Party Y, of accepting international campaign contributions, which is illegal. Such accusations are, however, ill founded. Three years ago, Party Y itself was involved in a scandal in which it was discovered that its national committee seriously violated campaign laws.
Which one of the following contains flawed reasoning most similar to the flawed reasoning in the argument above?
The plaintiff accuses the defendant of violating campaign laws, but the accusations are ill founded. While the defendant's actions may violate certain laws, they are not immoral, because the laws in question are unjust.
The plaintiff accuses the defendant of violating campaign laws, but these accusations show the plaintiff to be hypocritical, because the plaintiff has engaged in similar conduct.
The plaintiff accuses the defendant of violating campaign laws, and, in the past, courts have declared such violations illegal. Nevertheless, because the plaintiff recently engaged in actions that were similar to those of the defendant, the plaintiff's accusations are ill founded.
The plaintiff accuses the defendant of violating campaign laws, but these accusations are ill founded. They are clearly an attempt to stir up controversy, because they were made just two weeks before the election.
The plaintiff accuses the defendant of voting only for campaign laws that would favor the defendant's party. This accusation is ill founded, however, because it attacks the defendant's motivations instead of addressing the arguments the defendant has put forth justifying these votes.
The plaintiff accuses the defendant of violating campaign laws, and, in the past, courts have declared such violations illegal. Nevertheless, because the plaintiff recently engaged in actions that were similar to those of the defendant, the plaintiff's accusations are ill founded.
Detective: People who repeatedly commit crimes like embezzlement or bribery without being caught tend to become more confident. With each success, they believe that getting caught is less likely. However, the more crimes a person commits, the greater the chance that one of those crimes will be solved. It is therefore likely that most people who commit embezzlement or bribery will eventually be caught.
Which one of the following is an assumption required by the detective's argument?
The majority of people who commit embezzlement or bribery do so repeatedly.
People who commit embezzlement or bribery tend to be people who feel confident.
Embezzlement and bribery are more likely to be solved than are many other types of crimes.
People who repeatedly commit embezzlement or bribery become more and more careless the longer they avoid detection.
No one who commits embezzlement or bribery is ever caught the first time.
The majority of people who commit embezzlement or bribery do so repeatedly.
Animal feed should not include genetically modified plants. A study found that laboratory rats fed genetically modified potatoes for 30 days tended to develop intestinal deformities and a weakened immune system, whereas rats fed a normal diet of foods that were not genetically modified did not develop these problems.
Which one of the following, if true, most weakens the argument?
Potatoes are not normally a part of the diet of laboratory rats.
The rats tended to eat more of the genetically modified potatoes at the beginning of the 30 days than they did toward the end of the 30 days.
Intestinal deformities at birth are not uncommon among rats bred in laboratory conditions.
Genetically modified potatoes have the same nutritional value to rats as do potatoes that are not genetically modified.
The researchers conducting the study were unable to explain how the genetic modifications of the potatoes would have caused the intestinal deformities or a weakened immune system in the rats.
Potatoes are not normally a part of the diet of laboratory rats.
It is a principle of economics that a nation can experience economic growth only when consumer confidence is balanced with a small amount of consumer skepticism.
Which one of the following is an application of the economic principle above?
A. Any nation in which consumer confidence is balanced with a small amount of consumer skepticism will experience economic growth.
B. Any nation in which the prevailing attitude of consumers is not skepticism will experience economic growth.
C. Any nation in which the prevailing attitude of consumers is either exclusively confidence or exclusively skepticism will experience economic growth.
D. Any nation in which the prevailing attitude of consumers is exclusively confidence will not experience economic growth.
E. Any nation in which consumer skepticism is balanced with a small amount of consumer confidence will experience economic growth.
D. Any nation in which the prevailing attitude of consumers is exclusively confidence will not experience economic growth.
Some theorists argue that literary critics should strive to be value-neutral in their literary criticism. These theorists maintain that by exposing the meaning of literary works without evaluating them, critics will enable readers to make their own judgments about the works' merits. But literary criticism cannot be completely value-neutral. Thus, some theorists are mistaken about what is an appropriate goal for literary criticism.
The argument's conclusion follows logically if which one of the following is assumed?
Any critic who is able to help readers make their own judgments about literary works' merits should strive to produce value-neutral criticism.
If it is impossible to produce completely value-neutral literary criticism, then critics should not even try to be value-neutral.
Critics are more likely to provide criticisms of the works they like than to provide criticisms of the works they dislike.
The less readers understand the meaning of a literary work, the less capable they will be of evaluating that work's merits.
Critics who try to avoid rendering value judgments about the works they consider tend to influence readers' judgments less than other critics do.
If it is impossible to produce completely value-neutral literary criticism, then critics should not even try to be value-neutral.
Amoebas, like human beings, generally withdraw from stimuli that cause them physical damage. Humans do this because such stimuli cause them pain. Thus all microscopic organisms must also be capable of feeling pain.
Which one of the following exhibits flawed reasoning most similar to that exhibited by the argument above?
Poets, like people under hypnosis, frequently use language in odd, incomprehensible ways. People under hypnosis do this because their inhibitions are lower than those of most people. Thus all artists must have lower inhibitions than most people have.
Like nonprofit organizations, corporations usually provide some free public services. Nonprofit organizations do this solely because of their members' desire to make the world a better place. Thus this is probably also the main motive of most corporations.
Most professional athletes practice regularly for the same reason. Professional boxers spend several hours a day practicing in order to excel in competition. Thus professional skaters probably also practice in order to excel in competition.
Predatory birds, like many predatory animals, are generally solitary hunters. Some predatory mammals hunt alone because there is not enough food to support a pack of them in one area. Thus hawks, which are predatory birds, probably hunt alone.
Hiking trails in British Columbia, like those in New Mexico, are concentrated in mountainous regions. In New Mexico this is partly because low-lying areas are too hot and arid for comfortable hiking. Thus hikers must also feel less comfortable hiking in low-lying areas of British Columbia.
Poets, like people under hypnosis, frequently use language in odd, incomprehensible ways. People under hypnosis do this because their inhibitions are lower than those of most people. Thus all artists must have lower inhibitions than most people have.
In early 2003, scientists detected methane in the atmosphere of Mars. Methane is a fragile compound that falls apart when hit by the ultraviolet radiation in sunlight. So any methane in the Martian atmosphere must have been released into the atmosphere relatively recently.
The argument relies on the assumption thatMars had no methane in its atmosphere prior to 2003
all methane in the Martian atmosphere is eventually exposed to sunlight
methane cannot be detected until it has started to fall apart
the methane that the scientists detected had been exposed to ultraviolet radiation
methane in Earth's atmosphere does not fall apart as a result of exposure to ultraviolet radiation
all methane in the Martian atmosphere is eventually exposed to sunlight
A positive correlation has been found between the amount of soot in the atmosphere of cities and the frequency of a certain ailment among those cities' populations. However, the soot itself probably does not cause this ailment, since in cities where there are large amounts of soot in the air, there are usually also high concentrations of many other air pollutants.
Which one of the following statements, if true, most weakens the argument?
In cities where there are high concentrations of many air pollutants but little if any soot in the air, the frequency of the ailment is just as high, on average, as it is in cities where there are large amounts of soot in the air.
If the ailment rarely occurs except in cities in which there are large amounts of soot in the air, then the soot is probably the cause of the ailment.
In each of the cities where there are large amounts of soot in the air but little other air pollution, the frequency of the ailment is at least as high as it is anywhere else.
If high concentrations of many different pollutants in a city's air are correlated with a high frequency of the ailment among that city's population, then it is possible that two or more of those pollutants each causally contributes to the ailment.
In cities in which there are high concentrations of many air pollutants, there are generally also high concentrations of other forms of pollution that are very likely to contribute causally to the ailment.
In each of the cities where there are large amounts of soot in the air but little other air pollution, the frequency of the ailment is at least as high as it is anywhere else.
Counselor: Constantly comparing oneself to those one sees as more able or more successful almost invariably leads to self-disparagement. Conversely, constantly comparing oneself to those one sees as less able or less successful almost invariably leads to being dismissive of others. So, those who for the most part refrain from comparing themselves to others will most likely be, on the whole, self-accepting and accepting of others.
The counselor’s reasoning is most vulnerable to criticism because it
A. overlooks the possibility that one can compare oneself both to those one perceives to be more able and more successful than oneself and to those one perceives to be less able and less successful than oneself
B. overlooks the possibility that constantly comparing oneself to others may have beneficial effects that those who refrain from making such comparisons are deprived of
C. takes for granted that if one is both dismissive of others and self-disparaging, one will not be self-accepting and accepting of others
D. overlooks the possibility that self-disparagement and being dismissive of others can result from something other than comparing oneself to others
E. takes for granted that whenever one compares oneself to others one sees them as more successful and more able than oneself or less successful and less able than oneself
D. overlooks the possibility that self-disparagement and being dismissive of others can result from something other than comparing oneself to others
Clearly, a democracy cannot thrive without effective news media. After all, a democracy cannot thrive without an electorate that is knowledgeable about important political issues, and an electorate can be knowledgeable in this way only if it has access to unbiased information about the government.
24. The argument's conclusion is properly inferred if which one of the following is assumed?
A All societies that have effective news media are thriving democracies.
B If an electorate has access to unbiased information about the government, then that electorate will be knowledgeable about important political issues.
C A democracy will thrive if its electorate is knowledgeable about important political issues.
D A democracy cannot thrive if the electorate is exposed to biased information about the government.
E Without effective news media, an electorate will not have access to unbiased information about the government.
If the prosecutor wanted to charge Frank with embezzlement, then Frank would already have been indicted. But Frank has not been indicted. So clearly Frank is not an embezzler.
The flawed pattern of reasoning exhibited by which one of the following is most similar to that exhibited by the argument above?
If Rosita knew that her 9:00 appointment would cancel, she would not come in to work until 10:00. She did not come in until 10:00. So she must have known her 9:00 appointment would cancel.
If Barry had won the lottery, he would stay home to celebrate. But Barry did not win the lottery, so he will be in to work today.
If Makoto believed that he left the oven on, he would rush home. But Makoto is still at work. So obviously he did not leave the oven on.
If Tamara believed she was getting a promotion, she would come in to work early. She did come in early. So apparently she is getting a promotion.
If Lucy believed she was going to be fired, she would not come in to work today. She is going to be fired, so clearly she will not be coming in today.
If Makoto believed that he left the oven on, he would rush home. But Makoto is still at work. So obviously he did not leave the oven on.
From time to time there is a public outcry against predatory pricing—where a company deliberately sells its products at prices low enough to drive its competitors out of business. But this practice clearly should be acceptable, because even after its competitors go out of business, the mere threat of renewed competition will prevent the company from raising its prices to unreasonable levels.
Which one of the following is an assumption on which the argument depends?
Any company that is successful will inevitably induce competitors to enter the market.
It is unlikely that several competing companies will engage in predatory pricing simultaneously.
Only the largest and wealthiest companies can engage in predatory pricing for a sustained period of time.
It is only competition or the threat of competition that keeps companies from raising prices.
Any pricing practice that does not result in unreasonable prices should be acceptable.
Any pricing practice that does not result in unreasonable prices should be acceptable.
Though Earth's human population is increasing, it currently uses only a relatively small fraction of the supply of fresh water. Thus, claims that water shortages will plague humankind in the near future unless population growth trends change are simply mistaken.
Which one of the following, if true, most seriously weakens the argument above?
Population growth trends are notoriously hard to predict with reasonable accuracy.
The amount of fresh water available to meet the needs of Earth's population varies significantly from region to region.
Not all of Earth's population will adopt water conservation methods in the near future.
If Earth's population continues to increase, it will eventually outstrip all available resources.
The percentage of fresh water used for agriculture is likely to grow more quickly than is the percentage used for industry.
The amount of fresh water available to meet the needs of Earth's population varies significantly from region to region.
Only computer scientists understand the architecture of personal computers, and only those who understand the architecture of personal computers appreciate the advances in technology made in the last decade. It follows that only those who appreciate these advances are computer scientists.
Which one of the following most accurately describes a flaw in the reasoning in the argument?
A. The argument contains no stated or implied relationship between computer scientists and those who appreciate the advances in technology in the last decade.
B. The argument ignores the fact that some computer scientists may not appreciate the advances in technology made in the last decade.
C. The argument ignores the fact that computer scientists may appreciate other things besides the advances in technology made in the last decade.
D. The premises of the argument are stated in such a way that they exclude the possibility of drawing any logical conclusion.
E. The premises of the argument presuppose that everyone understands the architecture of personal computers.
B. The argument ignores the fact that some computer scientists may not appreciate the advances in technology made in the last decade.
If the budget does not allow for more dairy inspectors to be hired, most of the large dairies in the central valley will not meet federal standards governing the disposal of natural wastes, which can seep into streams and groundwater. The new district budget, however, does not allow for the hiring of more dairy inspectors. Consequently, most of the district's drinking water is likely to become polluted.
The conclusion above follows logically if which one of the following is assumed?
If most of the dairies in the central valley meet federal standards for the disposal of natural wastes, it is unlikely that most of the district's drinking water will become polluted.
To keep all the drinking water in the district clean requires more dairy inspectors to monitor the dairies' disposal of natural wastes.
All of the district's drinking water is likely to become polluted only if all of the large dairies in the central valley do not meet federal standards for the disposal of natural wastes.
Most of the district's drinking water is likely to become polluted if most of the large dairies in the central valley do not meet federal standards for the disposal of natural wastes.
If none of the large dairies in the central valley meets federal standards for the disposal of natural wastes, most of the district's drinking water is likely to become polluted.
Most of the district's drinking water is likely to become polluted if most of the large dairies in the central valley do not meet federal standards for the disposal of natural wastes.
If the concrete is poured while the ground is wet, it will not form a solid foundation. If the concrete does not form a solid foundation, it will either settle unevenly or crack. So if the concrete settles evenly, either it was poured while the ground was dry or it will crack.
Which one of the following arguments is most closely parallel in its reasoning to the reasoning in the argument above?
The film will not be properly exposed if the camera is not working properly. If the film is not properly exposed, then the photograph will be either blurred or dark. So if the photograph is not blurred, either the camera is working properly or the photograph will be dark.
If the camera is working properly, the photograph will not be blurred. The photograph will be blurred if the film is either not properly exposed or not properly developed. So if the camera is working properly, the film will be both properly exposed and properly developed.
The photograph will either be blurred or dark if the camera is not working properly. This photograph is not blurred, so if the photograph is not dark, the camera is working properly.
If the camera is working properly, the film will be properly exposed. If either the film is properly exposed or corrections are made during the developing process, the photograph will not be dark. So if the camera is working properly, the photograph will not be dark.
The camera will work properly only if the film is properly exposed. But the film cannot be properly exposed if there is either not enough or too much light. So the camera will not work properly if there is either too much or not enough light.
The film will not be properly exposed if the camera is not working properly. If the film is not properly exposed, then the photograph will be either blurred or dark. So if the photograph is not blurred, either the camera is working properly or the photograph will be dark.
Auditor: XYZ, a construction company, purchased 20 new trucks 3 years ago, and there is no record of any of those trucks being sold last year. Records indicate, however, that XYZ sold off all of its diesel-powered trucks last year. We can thus conclude that none of the 20 trucks purchased 3 years ago were diesel powered.
Which one of the following is an assumption required by the auditor's reasoning?
All of the trucks that XYZ sold last year were diesel powered.
XYZ did not purchase any used trucks 3 years ago.
XYZ did not purchase any new trucks since it purchased the 20 trucks 3 years ago.
None of the 20 trucks was sold before last year.
XYZ no longer owns any trucks that it purchased more than 3 years ago.
None of the 20 trucks was sold before last year.
Prolonged exposure to sulfur fumes permanently damages one's sense of smell. In one important study, 100 workers from sulfur-emitting factories and a control group of 100 workers from other occupations were asked to identify a variety of chemically reproduced scents, including those of foods, spices, and flowers. On average, the factory workers successfully identified 10 percent of the scents compared to 50 percent for the control group.
Each of the following, if true, weakens the argument except:
The chemicals used in the study closely but not perfectly reproduced the corresponding natural scents.
The subjects in the study were tested in the environments where they usually work.
Most members of the control group had participated in several earlier studies that involved the identification of scents.
Every sulfur-emitting factory with workers participating in the study also emits other noxious fumes.
Because of the factories' locations, the factory workers were less likely than those in the control group to have been exposed to many of the scents used in the study.
The chemicals used in the study closely but not perfectly reproduced the corresponding natural scents.