【文章內(nèi)容簡介】 1 2 170、 20 21 2 239 8 //Fifteen years ago, Omega University implemented a new procedure that encouraged students to evaluate the teaching effectiveness of all their professors. Since that time, Omega professors have begun to assign higher grades in their classes, and overall student grade averages at Omega have risen by thirty percent. Potential employers apparently believe the grades at Omega are inflated。 this would explain why Omega graduates have not been as successful at getting jobs as have graduates from nearby Alpha University. To enable its graduates to secure better jobs, Omega University should now terminate student evaluation of professors.// The argument also assumes unfairly that the gradeaverage increase is the result of the evaluation procedurerather than some other phenomenon. The only reason for this causal relation is that the evaluation procedure occurs before the gradeaverage increase. The dean ignores a host of other possible explanations for the increasesuch as a trend at Omega toward higher admission standards, or higher quality instruction or facilities. Without ruling out all other possible explanations for the gradeaverage increase, the dean cannot convince me that by terminating the evaluation procedure Omega would curb its perceived grade inflation let alone help its graduates get jobs. ●cum hoc, ergo propter hoc 7 8 1 15 20 225 //Ever since the 195039。s, when television sets began to appear in the average home, the rate of crimes mitted by teenagers in the country of Alta has steadily increased. This increase in teenage crime parallels the increase in violence shown on television. According to several national studies, even very young children who watch a great number of television shows featuring violent scenes display more violent behavior within their home environment than do children who do not watch violent shows. Furthermore, in a survey conducted by the Observer, over 90 percent of the respondents were parents who indicated that primetime televisionprograms that are shown between 7 . and 9 show less violence. Therefore, in order to lower the rate of teenage crime in Alta, television viewers should demand that television programmers reduce the amount of violence shown during prime time.// To begin with, the editorial observes a correlation between violence on television and violent teenage crime, then concludes that the former is the cause of the latter. However, the editorial fails to rule out other possible explanations for the rise in violent crime among teenagers. For example, since the 1950s it is entirely possible that Alta has seen a large growth in its population, or a deterioration of its juvenile justice system or economy. Any of these factors, or other social, political or economic factors, might lead to an increase in violent crime among teenagers. Without ruling out all other such factors it is unfair to conclude that television programs are responsible for this increase. 9 //During her three years in office, Governor Riedeburg has shown herself to be a worthy leader. Since she took office, crime has decreased, the number of jobs created per year has doubled, and the number of people choosing to live in our state has increased. These trends are likely to continue if she is reelected. In addition, Ms. Riedeburg has promised to take steps to keep big panies here, thereby providing jobs for any new residents. Anyone who looks at Ms. Riedeburg39。s record can tell that she is the bestqualified candidate for governor.// One problem with the argument is that the letter39。s author might be assigning a false cause to these statewide trends. The author provides no evidence that Riedeburg39。s policies and actions as governor were indeed the reason for these developments. Without such evidence, it is equally possible that other factors are instead responsible for the trends. For instance, perhaps the crime rate has declined due to legislative or judicial action over which Riedeburg had no control. Perhaps the rise in the state39。s population is the result of sociological trends that have nothing to do with Riedeburg39。s policies as governor. Or perhaps people are moving to the statefor other reasons, such as the state39。s climate. Moreover, the argument assumes that an increase in population is a positive development in the first place。 yet it is entirely possible that the state39。s residents properly view this trend as a negative one. If so, and if Riedeburg39。s policies have contributed to this trend, then the author cannot reasonably conclude based on this evidence that Riedeburg is the bestqualified candidate. ●Correlation to Causation 3 80、 90、 14 160 The article entitled 39。Eating Iron39。 in last month39。s issue of Eating for Health reported that a recent study found a correlation between high levels of iron in the diet and an increased risk of heart disease. Further, it is well established that there is a link between large amounts of red meat in the diet and heart disease, and red meat is high in iron. On the basis of the study and the wellestablished link between red meat and heart disease, we can conclude that the correlation between high iron levels and heart disease, then, is most probably a function of the correlation between red meat and heart disease. The following appeared as a letter to the editor of a national newspaper. Even assuming that the study is statistically reliable, a direct correlation between a highiron diet and heart disease does not necessarily prove that the former causes the latter. While a high correlation is strong evidence of a causal relationship, in itself it is not sufficient. The author must also account for all other possible factors leading to heart disease, such as geic propensity, amount of ex