为什么认知有困难
为什么认知是困难的一个原因是，很多长期没有答案的问题持续得不到解决，比如这些问题：什么导致了癌症？什么教育方法对孩子最好？在不侵害个人权利的前提下如何能防止犯罪？

另外一个原因是，每天都有新的情况发生，没有先例可以参考。当前额脑白质切除的脑部手术能够让暴力的人们冷静下来，这引发了一个治疗的道德问题，它剥夺了病人作为人的感受。当心脏移植和人工心脏成为现实，哪个病人应该优先的问题又出来了，如何获得捐献者也是同样的问题。当明确认为抽烟是许多致死疾病的原因因素时，我们被迫审视允许香烟广告误导电视观众并诱使他们伤害自己的智慧。最近，当证据表明吸烟会对非烟民造成和烟民一样的伤害时，关于烟民和非烟民在公共场所权利的争论出现了。

认知困难还有另外一个原因， 在世代传承时，知识经常被忘记或者不明智的被拒绝。比如，古希腊人知道鲸鱼有肺而不是鱼鳃，因此是哺乳动物。但是后来罗马人认为鲸鱼是鱼类，这个错误的概念一直占据着西方人的脑袋，直到十七世纪。在那时，有人提出，鲸鱼的确是哺乳动物，后来另一个人认定这是事实，西方重新发现了一项知识。

在我们的时代，“罪恶”和“自责”的观念已经被认为是没有用的，甚至是从维多利亚时代以来应该抛弃的有害理念。“新的道德规范”促使人们将这些旧的观念当作追寻幸福和满足的障碍而放在一边。后来一位杰出的美国精神病专家卡尔门宁格（ Karl Menninger），写了一本书《究竟什么导致了罪恶》（Whatever Became of Sin）。在书里他争论到，“罪恶”和“自责”的观念在文明社会中是有益的，必须的。他说，这意味着，我们的时代太快，太不明智的拒绝了这些概念。

知识通常被认为是堆放在阴暗图书馆堆满了灰尘书架上的死物。不幸的是，图书馆异常安静的气氛会让人想起殡仪馆或者公墓。这个表面现象欺骗了我们。这些书架上的观念非常活跃——并且常常互相之间激烈的互相斗争。考虑下面的案例。

哥伦布是从欧洲、非洲或亚洲来到北美洲或南美洲海岸的第一人这一观念一直未改变。却受到相反观念一次又一次地挑战。（反对哥伦布登陆理论的证据不断增多：在厄瓜多尔发现了日本古代陶器，公元前541年西顿的海员探访的痕迹。以及公元200年的希腊人和希伯来人，以及公元874年的维京人的痕迹。最近的证据表明，中国人可能在公元前2500年发现了美洲）。

奴隶制和贫困的历史导致非裔美国人的自尊心不如白人的观点众所周知。然而，康涅狄格大学的两位社会学家杰罗德·海斯和苏珊·欧文斯对它提出了质疑。他们的研究表明，中产阶级非洲裔美国人的自尊几乎与中产阶级白人的自尊相同，而下层非洲裔美国人的自尊高于下层白人。

当最小的孩子离开家庭的时候，中年父母，尤其是母亲，会变得非常沮丧，并感到他们的生活已经结束，这一观点有许多信徒。然而，至少有一项研究反对这一观点。它表明许多父母，也许是大多数人，一点也不沮丧；相反，他们希望过一种更简单、要求更低的生活。

同样地，直到最近，大多数科学家都承认衰老是大脑生理退化的结果，是渐进的和不可逆转的。然后，阿拉巴马州一家退伍军人医院的实验人员发现，在许多情况下，老年人的困惑、迷失方向和脱离现实的症状可以通过“一个让老年人不断与周围环境保持联系的简单计划”来停止甚至逆转。

关于运动员“喘气后恢复正常”的书籍和文章非常多。然而，犹他大学的尼尔斯·汉弗莱和罗伯特·鲁林提出了证据，说明实际上没有这么回事，许多运动员的感受仅仅因为心理上的因素。

原文：
Why Knowing Is Difficult
One reason why knowing is difficult is that some long unanswered questions continue to resist solution, questions like What causes cancer? What approach to education is best for children? and How can we prevent crime without compromising individual rights?

Another reason is that everyday situations arise for which there are no precedents. When the brain procedure known as frontal lobotomy was developed to calm raging violence in people, it raised the question of the morality of a cure that robbed the patient of human sensibilities. When the heart transplant and the artificial heart became realities, the issue of which patients should be given priority was created, as well as the question of how donors were to be obtained. When smoking was definitely determined to be a causative factor in numerous fatal diseases, we were forced to examine the wisdom of allowing cigarette commercials to mislead TV viewers and entice them into harming themselves. More recently, when smoking was shown to harm the nonsmoker as well as the smoker, a debate arose concerning the rights of smokers and nonsmokers in public places.

Still another reason why knowing is difficult is that, as one generation succeeds another, knowledge is often forgotten or unwisely rejected. For example, the ancient Greeks knew that whales have lungs instead of gills and therefore are mammals. Later, however, the Romans regarded whales as fish, a false notion that persisted in Western minds until the seventeenth century. In that century one man suggested that whales are really mammals, another later established it as fact, and the West rediscovered an item of knowledge.11

In our time the ideas of “sin” and “guilt” have come to be regarded as useless and even harmful holdovers from Victorian times. The “new morality” urged people to put aside such old-fashioned notions as obstacles to happiness and fulfillment. Then Karl Menninger, one of America’s leading psychiatrists, wrote a book called Whatever Became of Sin? in which he argues that the notions of “sin” and “guilt” are good and necessary in civilized society.12 He says, in other words, that our age rejected those concepts too quickly and quite unwisely.

Knowledge is often thought of as dead matter stored on dusty shelves in dull libraries. Unfortunately, the hushed atmosphere of a library can suggest a funeral chapel or a cemetery. But the appearance is deceiving.

The ideas on those shelves are very much alive—and often fighting furiously with one another. Consider the following cases. The idea that Columbus was the first person from Europe, Africa, or Asia to land on the shores of North or South America hangs on tenaciously. The opposing idea challenges this again and again. (The evidence against the Columbus theory continues to mount: the discovery of ancient Japanese pottery in Ecuador, traces of visits by seafarers from Sidon in 541 B.C. as well as by the Greeks and Hebrews in A.D. 200 and by the Vikings in A.D. 874.13 The most recent evidence suggests that the Chinese may have discovered America by 2500 B.C.)14

The idea that a history of slavery and deprivation has caused African Americans to have less self-esteem than whites was well established. Then it was challenged by two University of Connecticut sociologists, Jerold Heiss and Susan Owens. Their studies indicate that the self-esteem of middle-class African Americans is almost identical to that of middleclass whites and that the self-esteem of lower-class African Americans is higher than that of lower-class whites.15

The notion that when the youngest child leaves home, middle-aged parents, especially mothers, become deeply depressed and feel that life is over for them has many believers. Yet at least one study attacks that notion. It shows that many, perhaps most, parents are not depressed at all; rather, they look forward to a simpler, less demanding, life.16

Similarly, until recently, most scientists accepted that senility is a result of the physical deterioration of the brain and is both progressive and irreversible. Then experimenters in an Alabama veterans’ hospital found that in many cases the symptoms of senility—confusion, disorientation, and withdrawal from reality—can be halted and even reversed by “a simple program of keeping the aged constantly in touch with the surrounding environment.”17
Books and articles referring to athletes’ “second wind” abound. Yet Nyles Humphrey and Robert Ruhling of the University of Utah have presented evidence that there really is no second wind and that the sensation experienced by many athletes is merely psychological.18