经济学人:六大经济思想之五:纳什均衡(上)

 　　Economics brief: six big ideas.

　　经济概要：六大经济思想。

　　Game theory: Prison breakthrough

　　博弈论：越狱

　　The fifth of our series on seminal¹ economic ideas looks at the Nash equilibrium².

　　六大经济思想之五——纳什均衡。

　　JOHN NASH arrived at Princeton University in 1948 to start his PhD with a one-sentence recommendation: “He is a mathematical genius”.

　　1948年，约翰·纳什带着一句话的推荐信——他是一个数学天才——来到普林斯顿大学开始读博。

　　He did not disappoint.

　　他没有令人失望。

　　Aged³ 19 and with just one undergraduate economics course to his name, in his first 14 months as a graduate he produced the work that would end up, in 1994, winning him a Nobel prize in economics for his contribution to game theory.

　　年仅19岁且名下只有一个经济学课程的他，在读博的头14月中就交出了最终会在1994年因为对博弈论的贡献而为他赢得了诺贝尔经济学奖的研究。

　　On November 16th 1949, Nash sent a note barely longer than a page to the Proceedings⁴ of the National Academy of Sciences, in which he laid out the concept that has since become known as the “Nash equilibrium”.

　　1949年11月16日，纳什给《美国国家科学院院刊》寄去了一份刚够一页纸长的笔记，在这份笔记中，他提出了自此闻名遐迩的“纳什均衡”概念。

　　This concept describes a stable outcome that results from people or institutions making rational choices based on what they think others will do.

　　这个概念描述了一种源自个人或机构基于自身之于别人将做什么的认识而做出理性选择的稳定结果。

　　In a Nash equilibrium, no one is able to improve their own situation by changing strategy: each person is doing as well as they possibly can, even if that does not mean the optimal⁵ outcome for society.

　　在纳什均衡中，无人能够通过改变策略而改善自身境况：每一个人都在尽其所能地做事，虽然这不意味着社会的最佳结果。

　　With a flourish of elegant mathematics, Nash showed that every “game” with a finite number of players, each with a finite number of options to choose from, would have at least one such equilibrium.

　　借助于优雅数学的表述，纳什告诉人们：每一场参与者数量有限每一位参与者可供选择的选项数量也是有限的“博弈”都至少会有一个这样的均衡。

　　His insights expanded the scope of economics.

　　他的高见扩展了经济学的范围。

　　In perfectly⁶ competitive markets, where there are no barriers to entry and everyone's products are identical, no individual buyer or seller can influence the market: none need pay close attention to what the others are up to.

　　在完全竞争市场中，没有进入门槛且所有人的产品都完全相同，没有单独的买方或卖方能够影响市场：谁也不需要密切关注别人正在忙什么。

　　But most markets are not like this: the decisions of rivals and customers matter.

　　但是，大多数市场不是如此：对手和客户的决定至关重要。

　　From auctions⁷ to labour markets, the Nash equilibrium gave the dismal⁸ science a way to make real-world predictions based on information about each person's incentives⁹.

　　从拍卖到劳动力市场，纳什均衡给这门沉闷科学提供了一种基于每一个人的动机信息做出现实生活预测的方法。

　　One example in particular has come to symbolise the equilibrium: the prisoner's dilemma¹¹.

　　一个例子尤其代表了这种均衡：囚徒困境。

　　Nash used algebra¹² and numbers to set out this situation in an expanded paper published in 1951, but the version familiar to economics students is altogether more gripping.

　　纳什曾在1951年发表的一篇延伸论文中运用代数和数字论述了这种情景。但是，经济学学生熟悉的版本更为吸引人。

　　(Nash's thesis adviser¹³, Albert Tucker, came up with it for a talk he gave to a group of psychologists. )

　　(纳什的论文导师阿尔伯特·塔克尔曾在对一群心理学家的谈话中提到过它。)

　　It involves two mobsters sweating in separate prison cells, each contemplating¹⁴ the same deal offered by the district attorney.

　　它说的是两名正在单独牢房中如坐针毡的犯罪分子，每个人都在考虑由地区检察官提出的同样交易。

　　If they both confess to a bloody¹⁵ murder, they each face ten years in jail.

　　如果他们双双承认身犯命案，每人都面临十年牢狱。

　　If one stays quiet while the other snitches, then the snitch will get a reward, while the other will face a lifetime in jail.

　　如果一个人坚持不说，另一个人告密揭发，告密之人将得到奖赏，而另外那个人将面临终身监禁；

　　And if both hold their tongue, then they each face a minor¹⁶ charge, and only a year in the clink.

　　如果两人都闭口不言，那么，每个人都面临较小的指控，而且只有一年刑期。

　　There is only one Nash-equilibrium solution to the prisoner's dilemma: both confess.

　　对这种囚徒困境，只存在一种纳什均衡的解决方案：两人双双坦白。

　　Each is a best response to the other's strategy; since the other might have spilled the beans, snitching avoids a lifetime in jail.

　　每一方的坦白都是对对方策略的最佳应对；因为另一个人可能说漏嘴，告密揭发避免了终身监禁。

　　The tragedy is that if only they could work out some way of co-ordinating, they could both make themselves better off.

　　悲剧就在于，如果他们能够找到合作之法，两人都可能让自己的处境好起来。

　　The example illustrates¹⁷ that crowds can be foolish as well as wise; what is best for the individual can be disastrous¹⁸ for the group.

　　这个例子表明，除了明智之外，众人也可能是愚蠢的；个体的最佳可能是集体的灾难。

　　This tragic¹⁹ outcome is all too common in the real world.

　　在现实世界中，这种悲剧性结果太常见了。

　　Left freely to plunder²⁰ the sea, individuals will fish more than is best for the group, depleting²¹ fish stocks.

　　耗尽渔业资源的涸泽而渔，利在个人，弊在集体；

　　Employees competing to impress their boss by staying longest in the office will encourage workforce²² exhaustion²³.

　　通过最长时间地待在办公室中的办法而博得老板印象的雇员将鼓励员工耗尽精力；

　　Banks have an incentive¹⁰ to lend more rather than sit things out when house prices shoot up.

　　房价大涨的时候，银行有动力放出更多贷款，而不是袖手旁观。

　　The Nash equilibrium helped economists²⁵ to understand how self-improving individuals could lead to self-harming crowds.

　　纳什均衡曾给经济学家理解自我完善的个人如何能够成为自暴伤害的大众提供了帮助。

　　Better still, it helped them to tackle the problem: they just had to make sure that every individual faced the best incentives possible.

　　更重要的是，它还曾帮助他们去解决这个问题：他们只需确认，每一个单独的个人都面对最佳激励可能。

　　If things still went wrong—parents failing to vaccinate²⁶ their children against measles²⁷, say—then it must be because people were not acting²⁸ in their own self-interest.

　　如果仍然出现问题——例如父母没能让孩子接种麻疹疫苗——那么，这必然是因为当时人们没有以符合自身利益的方式行事。

　　In such cases, the public-policy challenge would be one of information.

　　在这种情况下，公共政策的挑战会是信息的挑战。

　　Nash's idea had antecedents.

　　纳什的思想有先例。

　　In 1838 August Cournot, a French economist²⁴, theorised that in a market with only two competing companies, each would see the disadvantages of pursuing market share by boosting output, in the form of lower prices and thinner profit margins²⁹.

　　1838年，法国经济学家奥古斯丁·古诺提出了下面这种理论：在只有两家竞争公司的市场中，每一家公司都会看到通过提高产出，以更低的价格和更微薄的利润形式，来追求市场份额的弊端。

　　Unwittingly, Cournot had stumbled across an example of a Nash equilibrium.

　　有意无意之间，古诺发现了一个纳什均衡的例子。

　　It made sense for each firm to set production levels based on the strategy of its competitor; consumers, however, would end up with less stuff and higher prices than if full-blooded competition had prevailed.

　　对于每一家来说，根据竞争对手的策略决定生产水平是有意义的；然而，在激烈竞争占上风的前提下，消费者最终面对越来越少的商品和越来越高的价格。

　　Another pioneer was John von Neumann, a Hungarian mathematician³⁰.

　　另一位先驱是匈牙利数学家约翰·冯·诺依曼。

　　In 1928, the year Nash was born, von Neumann outlined a first formal theory of games, showing that in two-person, zero-sum games, there would always be an equilibrium.

　　1928年，即纳什出生的那一年，冯·诺依曼概述了最早的正式博弈论，表明，在两人的零和博弈中，向来存在一种均衡。

　　When Nash shared his finding with von Neumann, by then an intellectual demigod, the latter dismissed the result as “trivial”, seeing it as little more than an extension of his own, earlier proof.

　　当纳什把自己的发现与当时已是知识分子偶像的冯·诺依曼分享时，后者斥之为 “无关紧要” 的结果，认为它不过是他自己早期证明的一种延伸而已。

　　In fact, von Neumann's focus on two-person, zero-sum games left only a very narrow set of applications for his theory.

　　实际上，冯·诺依曼之于两人零和博弈的强调只给他的理论留下了非常狭窄的应用。

　　Most of these settings were military in nature.

　　这些前提大都是军事性的。

　　One such was the idea of mutually assured destruction, in which equilibrium is reached by arming adversaries³¹ with nuclear weapons (some have suggested that the film character of Dr Strangelove was based on von Neumann) .

　　其中之一就是其中的均衡是由于装备了核武器的的对手才达到的相互确保毁灭的思想。(有人认为，奇爱博士这位电影人物就是以冯·诺依曼为原型的) .

　　None of this was particularly useful for thinking about situations—including most types of market—in which one party's victory does not automatically imply the other's defeat.

　　在这些前提中，没有一种对考虑一方的胜利并非自动地意味着另一方的失败的情形——包括大多数类型的市场——特别有用。

　　Even so, the economics profession initially³² shared von Neumann's assessment³³, and largely overlooked Nash's discovery.

　　即便如此，经济学界一开始还是认可了冯·诺依曼的评估，并在很大程度上忽视了纳什的发现。

　　He threw himself into other mathematical pursuits, but his huge promise was undermined when in 1959 he started suffering from delusions³⁴ and paranoia³⁵.

　　纳什一头扎进了自己在数学方面的其他追求，但是，当他在1959年开始遭受幻觉和强迫症折磨时他的远大前程遭遇了灭顶之灾。

　　His wife had him hospitalised; upon his release, he became a familiar figure around the Princeton campus, talking to himself and scribbling³⁶ on blackboards.

　　他的妻子把他送进了医院；出院后，他成了普林斯顿校园中的一个熟悉的身影，不是自言自语，就是在黑板上涂涂写写。

　　1.end up 结束

　　例句:The result was that the engine ended up at the bottom of the canal.

　　结果引擎最终沉到了运河底。

　　2.nuclear weapons 核武器

　　例句:The declaration deals with disarmament and the non-proliferation of nuclear weapons.

　　该声明涉及裁军和防止核武器扩散问题。

　　3.self-interest 利己主义

　　例句:Their current protests are motivated purely³⁷ by self-interest.

　　他们当前的抗议完全是受一己之利驱使的。

　　4.focus on 专注于

　　例句:The talks will focus on economic development of the region.

　　会谈将着重讨论该地区的经济发展。

1 seminal   

adj.影响深远的；种子的

参考例句：

• The reforms have been a seminal event in the history of the NHS.这些改革已成为英国国民保健制度史上影响深远的一件大事。
• The emperor's importance as a seminal figure of history won't be diminished.做为一个开创性历史人物的重要性是不会减弱的。

2 equilibrium   

n.平衡，均衡，相称，均势，平静

参考例句：

• Change in the world around us disturbs our inner equilibrium.我们周围世界的变化扰乱了我们内心的平静。
• This is best expressed in the form of an equilibrium constant.这最好用平衡常数的形式来表示。

3 aged   

adj.年老的，陈年的

参考例句：

• He had put on weight and aged a little.他胖了，也老点了。
• He is aged,but his memory is still good.他已年老，然而记忆力还好。

4 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼

5 optimal   

adj.最适宜的；最理想的；最令人满意的

参考例句：

• What is the optimal mix of private and public property rights in natural resources?私人和国家的自然资源产权的最适宜的组合是什么？
• Optimal path planning is a key link for the sailing contest.帆船最优行驶路径规划是帆船比赛取胜的关键环节。

6 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。

7 auctions   

n.拍卖，拍卖方式( auction的名词复数 )

参考例句：

• They picked up most of the furniture at auctions in country towns. 他们大部分的家具都是在乡村镇上的拍卖处买的。 来自辞典例句
• Our dealers didn't want these cars, so we had to dump them at auctions. 我们的承销商都不要这些车子，因此我们只好贱价拍卖。 来自辞典例句

8 dismal   

adj.阴沉的，凄凉的，令人忧郁的，差劲的

参考例句：

• That is a rather dismal melody.那是一支相当忧郁的歌曲。
• My prospects of returning to a suitable job are dismal.我重新找到一个合适的工作岗位的希望很渺茫。

9 incentives   

激励某人做某事的事物( incentive的名词复数 )； 刺激； 诱因； 动机

参考例句：

• tax incentives to encourage savings 鼓励储蓄的税收措施
• Furthermore, subsidies provide incentives only for investments in equipment. 更有甚者，提供津贴仅是为鼓励增添设备的投资。 来自英汉非文学 - 环境法 - 环境法

10 incentive   

n.刺激；动力；鼓励；诱因；动机

参考例句：

• Money is still a major incentive in most occupations.在许多职业中，钱仍是主要的鼓励因素。
• He hasn't much incentive to work hard.他没有努力工作的动机。

11 dilemma   

n.困境，进退两难的局面

参考例句：

• I am on the horns of a dilemma about the matter.这件事使我进退两难。
• He was thrown into a dilemma.他陷入困境。

12 algebra   

n.代数学

参考例句：

• He was not good at algebra in middle school.他中学时不擅长代数。
• The boy can't figure out the algebra problems.这个男孩做不出这道代数题。

13 adviser   

n.劝告者，顾问

参考例句：

• They employed me as an adviser.他们聘请我当顾问。
• Our department has engaged a foreign teacher as phonetic adviser.我们系已经聘请了一位外籍老师作为语音顾问。

14 contemplating   

深思，细想，仔细考虑( contemplate的现在分词 )； 注视，凝视； 考虑接受（发生某事的可能性）； 深思熟虑，沉思，苦思冥想

参考例句：

• You're too young to be contemplating retirement. 你考虑退休还太年轻。
• She stood contemplating the painting. 她站在那儿凝视那幅图画。

15 bloody   

adj.非常的的；流血的；残忍的；adv.很；vt.血染

参考例句：

• He got a bloody nose in the fight.他在打斗中被打得鼻子流血。
• He is a bloody fool.他是一个十足的笨蛋。

16 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

17 illustrates   

给…加插图( illustrate的第三人称单数 )； 说明； 表明； （用示例、图画等）说明

参考例句：

• This historical novel illustrates the breaking up of feudal society in microcosm. 这部历史小说是走向崩溃的封建社会的缩影。
• Alfred Adler, a famous doctor, had an experience which illustrates this. 阿尔弗莱德 - 阿德勒是一位著名的医生，他有过可以说明这点的经历。 来自中级百科部分

18 disastrous   

adj.灾难性的，造成灾害的；极坏的，很糟的

参考例句：

• The heavy rainstorm caused a disastrous flood.暴雨成灾。
• Her investment had disastrous consequences.She lost everything she owned.她的投资结果很惨，血本无归。

19 tragic   

adj.悲剧的，悲剧性的，悲惨的

参考例句：

• The effect of the pollution on the beaches is absolutely tragic.污染海滩后果可悲。
• Charles was a man doomed to tragic issues.查理是个注定不得善终的人。

20 plunder   

vt.劫掠财物，掠夺；n.劫掠物，赃物；劫掠

参考例句：

• The thieves hid their plunder in the cave.贼把赃物藏在山洞里。
• Trade should not serve as a means of economic plunder.贸易不应当成为经济掠夺的手段。

21 depleting   

使大大的减少，使空虚( deplete的现在分词 )； 耗尽，使枯竭

参考例句：

• Regulations are outlawing certain refrigerants, such as chlorofluorocarbons, which contain ozone-depleting chemicals. 随后出台的政策禁用了部分制冷剂，如破坏臭氧层的氟氯碳化合物。
• Aging, being a series of continual losses, can be keenly depleting. 老龄化，作为一个系列的连续亏损，可以清楚地消耗。

22 workforce   

n.劳动大军，劳动力

参考例句：

• A large part of the workforce is employed in agriculture.劳动人口中一大部分受雇于农业。
• A quarter of the local workforce is unemployed.本地劳动力中有四分之一失业。

23 exhaustion   

n.耗尽枯竭，疲惫，筋疲力尽，竭尽，详尽无遗的论述

参考例句：

• She slept the sleep of exhaustion.她因疲劳而酣睡。
• His exhaustion was obvious when he fell asleep standing.他站着睡着了，显然是太累了。

24 economist   

n.经济学家，经济专家，节俭的人

参考例句：

• He cast a professional economist's eyes on the problem.他以经济学行家的眼光审视这个问题。
• He's an economist who thinks he knows all the answers.他是个经济学家，自以为什么都懂。

25 economists   

n.经济学家，经济专家( economist的名词复数 )

参考例句：

• The sudden rise in share prices has confounded economists. 股价的突然上涨使经济学家大惑不解。
• Foreign bankers and economists cautiously welcomed the minister's initiative. 外国银行家和经济学家对部长的倡议反应谨慎。 来自《简明英汉词典》

26 vaccinate   

vt.给…接种疫苗；种牛痘

参考例句：

• Local health officials then can plan the best times to vaccinate people.这样，当地的卫生官员就可以安排最佳时间给人们接种疫苗。
• Doctors vaccinate us so that we do not catch smallpox.医生给我们打预防针使我们不会得天花。

27 measles   

n.麻疹，风疹，包虫病，痧子

参考例句：

• The doctor is quite definite about Tom having measles.医生十分肯定汤姆得了麻疹。
• The doctor told her to watch out for symptoms of measles.医生叫她注意麻疹出现的症状。

28 acting   

n.演戏，行为，假装；adj.代理的，临时的，演出用的

参考例句：

• Ignore her,she's just acting.别理她，她只是假装的。
• During the seventies,her acting career was in eclipse.在七十年代，她的表演生涯黯然失色。

29 margins   

边( margin的名词复数 )； 利润； 页边空白； 差数

参考例句：

• They have always had to make do with relatively small profit margins. 他们不得不经常设法应付较少的利润额。
• To create more space between the navigation items, add left and right margins to the links. 在每个项目间留更多的空隙，加左或者右的margins来定义链接。

30 mathematician   

n.数学家

参考例句：

• The man with his back to the camera is a mathematician.背对着照相机的人是位数学家。
• The mathematician analyzed his figures again.这位数学家再次分析研究了他的这些数字。

31 adversaries   

n.对手，敌手( adversary的名词复数 )

参考例句：

• That would cause potential adversaries to recoil from a challenge. 这会迫使潜在的敌人在挑战面前退缩。 来自辞典例句
• Every adversaries are more comfortable with a predictable, coherent America. 就连敌人也会因有可以预料的，始终一致的美国而感到舒服得多。 来自辞典例句

32 initially   

adv.最初，开始

参考例句：

• The ban was initially opposed by the US.这一禁令首先遭到美国的反对。
• Feathers initially developed from insect scales.羽毛最初由昆虫的翅瓣演化而来。

33 assessment   

n.评价；评估；对财产的估价，被估定的金额

参考例句：

• This is a very perceptive assessment of the situation.这是一个对该情况的极富洞察力的评价。
• What is your assessment of the situation?你对时局的看法如何？

34 delusions   

n.欺骗( delusion的名词复数 )；谬见；错觉；妄想

参考例句：

• the delusions of the mentally ill 精神病患者的妄想
• She wants to travel first-class: she must have delusions of grandeur. 她想坐头等舱旅行，她一定自以为很了不起。 来自辞典例句

35 paranoia   

n.妄想狂，偏执狂；多疑症

参考例句：

• Her passion for cleanliness borders on paranoia.她的洁癖近乎偏执。
• The push for reform is also motivated by political paranoia.竞选的改革运动也受到政治偏执狂症的推动。

36 scribbling   

n.乱涂[写]胡[乱]写的文章[作品]v.潦草的书写( scribble的现在分词 )；乱画；草草地写；匆匆记下

参考例句：

• Once the money got into the book, all that remained were some scribbling. 折子上的钱只是几个字！ 来自汉英文学 - 骆驼祥子
• McMug loves scribbling. Mama then sent him to the Kindergarten. 麦唛很喜欢写字，妈妈看在眼里，就替他报读了幼稚园。 来自互联网

37 purely   

adv.纯粹地，完全地

参考例句：

• I helped him purely and simply out of friendship.我帮他纯粹是出于友情。
• This disproves the theory that children are purely imitative.这证明认为儿童只会单纯地模仿的理论是站不住脚的。