Critical Reasoning

The country of Virodia has, until now, been barely self-sufficient in both meat and grain. Greater prosperity there has gone hand in hand with steadily increasing per capita consumption of meat, and it takes several pounds of grain used as feed to produce one pound of meat. Per capita income is almost certain to rise further, yet increases in domestic grain production are unlikely. Which of the following is most strongly supported by the information given?

Newspaper editors should not allow reporters to write the headlines for their own stories. The reason for this is that, while the headlines that reporters themselves write are often clever, what typically makes them clever is that they allude to little-known information that is familiar to the reporter but that never appears explicitly in the story itself. Which of the following, if true, most strengthens the argument?

Advertisement: Our competitors’ computer salespeople are paid according to the value of the products they sell, so they have a financial incentive to convince you to buy the most expensive units—whether you need them or not. But here at Comput-o-Mart, our salespeople are paid a salary that is not dependent on the value of their sales, so they won’t try to tell you what to buy. That means when you buy a computer at Comput-o-Mart, you can be sure you’re not paying for computing capabilities you don’t need. Which of the following would, if true, most weaken the advertisement’s reasoning?

Proponents of the recently introduced tax on sales of new luxury boats had argued that a tax of this sort would be an equitable way to increase government revenue because the admittedly heavy tax burden would fall only on wealthy people, and neither they nor anyone else would suffer any economic hardship. In fact, however, 20 percent of the workers employed by manufacturers of luxury boats have lost their jobs as a direct result of this tax. The information given, if true, most strongly supports which of the following?

In Wareland last year, 16 percent of licensed drivers under 21 and 11 percent of drivers ages 21–24 were in serious accidents. By contrast, only 3 percent of licensed drivers 65 and older were involved in serious accidents. These figures clearly show that the greater experience and developed habits of caution possessed by drivers in the 65-and-older group make them far safer behind the wheel than the younger drivers are. Which of the following is an assumption on which the argument depends?

In the past, the country of Malvernia has relied heavily on imported oil. Malvernia recently implemented a program to convert heating systems from oil to natural gas. Malvernia currently produces more natural gas each year than it uses, and oil production in Malvernian oil fields is increasing at a steady pace. If these trends in fuel production and usage continue, therefore, Malvernian reliance on foreign sources for fuel is likely to decline soon. Which of the following would it be most useful to establish in evaluating the argument?

Exposure to certain chemicals commonly used in elementary schools as cleaners or pesticides causes allergic reactions in some children. Elementary school nurses in Renston report that the proportion of schoolchildren sent to them for treatment of allergic reactions to those chemicals has increased significantly over the past ten years. Therefore, either Renston’s schoolchildren have been exposed to greater quantities of the chemicals or they are more sensitive to them than schoolchildren were ten years ago. Which of the following is an assumption on which the argument depends?

Lockeport’s commercial fishing boats use gill nets, which kill many of the netted fish, including some fish of endangered species. The fishing commission has proposed requiring the use of tent nets, which do not kill fish; boat crews would then throw back fish of endangered species. Profitable commercial fishing boats in similar areas have already switched over to tent nets. The proposal can therefore be implemented without economic harm to Lockeport’s commercial fishing boat operators. Which of the following, if true, casts the most serious doubt on the argument made for the proposal?

Normally, the pineal gland governs a person’s sleep-wake cycle by secreting melatonin in response to the daily cycle of light and darkness as detected by the eye. Nonetheless, many people who are totally blind due to lesions in the visual cortex of the brain easily maintain a 24-hour sleep-wake cycle. So the neural pathway by which the pineal gland receives information from the eye probably does not pass through the visual cortex. For purposes of evaluating the argument, it would be most useful to establish which of the following?

**In countries where automobile insurance includes compensation for whiplash injuries sustained in automobile accidents, reports of having suffered such injuries are twice as frequent as they are in countries where whiplash is not covered.** Presently, no objective test for whiplash exists, so it is true that spurious reports of whiplash injuries cannot be readily identified. Nevertheless, these facts do not warrant the conclusion drawn by some commentators that in the countries with the higher rates of reported whiplash injuries, half of the reported cases are spurious. Clearly, **in countries where automobile insurance does not include compensation for whiplash, people often have little incentive to report whiplash injuries that they actually have suffered.** In the argument given, the two boldfaced portions play which of the following roles?

Last year Comfort Airlines had twice as many delayed flights as the year before, but the number of complaints from passengers about delayed flights went up three times. It is unlikely that this disproportionate increase in complaints was rooted in an increase in overall dissatisfaction with the service Comfort Airlines provides, since the airline made a special effort to improve other aspects of its service last year. Which of the following, if true, most helps to explain the disproportionate increase in customer complaints?

Last year a global disturbance of weather patterns disrupted harvests in many of the world’s important agricultural areas. Worldwide production of soybeans, an important source of protein for people and livestock alike, was not adversely affected, however. Indeed, last year’s soybean crop was actually slightly larger than average. Nevertheless, the weather phenomenon is probably responsible for a recent increase in the world price of soybeans. Which of the following, if true, provides the strongest justification for the attribution of the increase in soybean prices to the weather phenomenon?

Most of the year, the hermit thrush, a North American songbird, eats a diet consisting mainly of insects, but in autumn, as the thrushes migrate to their Central and South American wintering grounds, they feed almost exclusively on wild berries. Wild berries, however, are not as rich in calories as insects, yet thrushes need to consume plenty of calories in order to complete their migration. One possible explanation is that berries contain other nutrients that thrushes need for migration and that insects lack. Which of the following, if true, most seriously calls into question the explanation given for the thrush’s diet during migration?

The kinds of hand and wrist injuries that result from extended use of a computer while maintaining an incorrect posture are common among schoolchildren in Harnville. Computers are important to the school curriculum there, so instead of reducing the amount their students use computers, teachers plan to bring about a sharp reduction in the number of these injuries by carefully monitoring their students’ posture when using computers in the classroom. Which of the following would it be most useful to know in order to assess the likelihood that the teachers’ plan will be successful?

A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants. Agronomists studying the growth of this herb have discovered that it produces large amounts of histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert. Hence, the herb’s high histidine production must be the key feature that allows it to grow in metal-rich soils. In evaluating the argument, it would be most important to determine which of the following?

Many people suffer an allergic reaction to certain sulfites, including those that are commonly added to wine as preservatives. However, since there are several winemakers who add sulfites to none of the wines they produce, people who would like to drink wine but are allergic to sulfites can drink wines produced by these winemakers without risking an allergic reaction to sulfites. Which of the following is an assumption on which the argument depends?

A new law gives ownership of patents—documents providing exclusive right to make and sell an invention—to universities, not the government, when those patents result from government-sponsored university research. Administrators at Logos University plan to sell any patents they acquire to corporations in order to fund programs to improve undergraduate teaching. Which of the following, if true, would cast the most doubt on the viability of the college administrators’ plan described above?

Since it has become known that **several of a bank’s top executives have been buying shares in their own bank**, the bank’s depositors, who had been worried by rumors that the bank faced impending financial collapse, have been greatly relieved. They reason that, since top executives evidently have faith in the bank’s financial soundness, those worrisome rumors must be false. Such reasoning might well be overoptimistic, however, since **corporate executives have been known to buy shares in their own company in a calculated attempt to dispel negative rumors about the company’s health.** In the argument given, the two boldfaced portions play which of the following roles?

Between 1980 and 2000, the sea otter population of the Aleutian Islands declined precipitously. There were no signs of disease or malnutrition, so there was probably an increase in the number of otters being eaten by predators. Orcas will eat otters when seals, their normal prey, are unavailable, and the Aleutian Islands seal population declined dramatically in the 1980s. Therefore, orcas were most likely the immediate cause of the otter population decline. Which of the following, if true, most strengthens the argument?

Political strategist: The domestic policies of our opponents in Party X are contrary to the priorities of many middle-class voters. Yet some of these same voters are supporters of Party X and its candidates due to the party’s appeals about foreign policy. In order to win these voters back, we in Party Y must prove to middle-class voters that Party X does not represent their priorities with respect to domestic policy. Which of the following would, if true, most strongly suggest that the political strategist’s plan is unlikely to succeed?