约翰·梅纳德·凯恩斯John Maynard Keynes

约翰·梅纳德·凯恩斯（发音为Canes）出生于一个学术家庭。他的父亲弗瑞兹·约翰 Nevile 凯恩斯是剑桥大学的讲师，教授逻辑学和政治经济学。约翰 Nevile在约翰 凯恩斯出生四个月后发表了Formal Logic。约翰 凯恩斯的母亲Florence Ada Brown是一位非凡的女性，她是一位非常成功的作家，也是社会改革的伟大先驱。在此阶段值得指出的是，尽管凯恩斯活到63岁，他的父母都比他长寿。

七岁时，凯恩斯进入珀斯学校幼儿园，但他从家中授课学到的更多。两年后，他进入St Faith's预备学校，但在这个阶段几乎没有迹象表明他是一个出类拔萃的学生。然而，随着时间的推移，他确实开始展现出更多的潜力，并在1894年首次名列班级第一，获得了数学奖。到1896年，校长这样描述他（例如见[6]）：-

……在学校的其他所有男孩中遥遥领先。

第二年，凯恩斯参加了伊顿公学的入学考试，在当年被该校录取的二十名男孩中排名第十。然而，他在数学方面并列第一。

凯恩斯在伊顿公学的学校生活过得很愉快。Harrod在[6]中写道：-

……伊顿公学极大地促进了他的发展。他在那里找到了与他意气相投的伙伴，那些才智出众的青年，他能够基于共同的兴趣迅速与他们建立起亲密的关系。

凯恩斯在伊顿公学表现出色，于1899年赢得高级数学奖，1900年再次获奖。但他在数学之外的领域同样出色；例如1901年，他在数学、历史和英语论文三项中均名列第一。1902年，他获得剑桥大学国王学院数学与古典学的奖学金。在结束对凯恩斯在伊顿公学时光的描述之前，我们应当注意到，正是在这里，他延续了自己的一个爱好（始于十二岁），即收集旧书。在1902年10月进入剑桥大学之前，他已购买了329本旧书。

凯恩斯的数学由欧内斯特·威廉·霍布森辅导，他称其为“霍贝玛”。尽管他学习数学，却并非数学天才。他的[6]：

……逻辑能力、准确性和闪电般的思维速度使他成为一名完全称职的数学家。他并无特定的数学天赋；他必须刻苦用功；……他并不去探寻那些令职业数学家心驰神往的深奥领域。

在剑桥，除了学业之外，他还有许多兴趣，大量时间与文学界朋友相处、阅读，并投身于政治活动[3]：

他曾任剑桥联盟主席，[并]以一篇关于伯克政治观点的论文赢得会员英语论文奖……

随着考试临近，他付出了一些努力以取得合理学位，并在1905年数学荣誉学位考试中位列第十二数学荣誉学位考试一等及格者（Wrangler），即在获得一等学位者的排名名单中位列第十二。

参加荣誉学位考试后，凯恩斯 立即开始认真研究经济学，阅读该学科的主要著作。他确实短暂考虑过参加第二次经济学荣誉学位考试，但决定不这样做。在瑞士度假后，他于1905年10月返回剑桥，并参加了阿尔弗雷德·马歇尔在那里讲授的经济学讲座。1906年8月，他参加了公务员考试，在当年录取的十人中排名第二。排名第一的人有权优先选择进入哪个部门，并选择进入财政部（如果 凯恩斯 排名第一，他也会这样做）。凯恩斯 作为下一个选择者，进入了印度事务部。

当 凯恩斯 收到考试的详细结果时，他非常不高兴。他在逻辑学、心理学和论文方面名列前茅，而最差的科目是数学和经济学。他对数学和经济学的结果都表示难以置信，并评论说——可能准确地——他对经济学的了解比他的考官更多。

印度事务部没有提供 凯恩斯 喜欢的职业。他主要做自己的工作，将所有业余时间用于研究 theory of probability。随后，他提交了一篇关于概率的学位论文，以申请国王学院的 fellowship。Johnson 和 阿尔弗雷德·诺思·怀特海 被任命为学位论文的评审人，但在1908年3月的一场激烈竞争后，凯恩斯 未能当选。1908年6月5日，他辞去印度事务部的职务，并在父亲的一些经济援助下，前往国王学院，希望能在次年的 fellowship 竞争中成功。

利用Johnson和阿尔弗雷德·诺思·怀特海对其概率论学位论文的详细评语，凯恩斯努力加以改进。他还与伯特兰·罗素讨论了自己的工作。在提交了概率论学位论文的新版本后，凯恩斯于1909年3月当选为会士。评语令人印象深刻；阿尔弗雷德·诺思·怀特海写道：-

……他的公理很好；它们简单且数量少，借助符号系统，他通过严密的推理从中推导出整个主题。他能够解决难题并发现前人工作中的歧义和错误的那种确定性和轻松，既例证了同时又几乎掩盖了他所取得的进展。

伯特兰·罗素在评论凯恩斯最终出版的关于概率论的著作时，高度赞扬了这部作品：-

考虑到构成其基础的极为有限的前提，数学微积分的力量令人惊讶……整本书是一部怎么赞扬都不为过的作品，希望它能激发对哲学和逻辑学家们过分忽视的一个最重要主题的进一步研究。

凯恩斯现在在剑桥教授经济学。他发表了统计学论文，特别是他在1910年和1911年发表于Journal of the Royal Statistical Society的信件中强烈抨击了卡尔·皮尔逊的工作。卡尔·皮尔逊还是凯恩斯在科学上更有理，尚有疑问，但毫无疑问凯恩斯在写信风格上要高明得多，使卡尔·皮尔逊（可能不公平地）显得相当愚蠢。凯恩斯还撰写了与印度相关的经济学著作，并于1913年出版了一部重要著作Indian Currency and Finance。这本书被认为是经典之作，其中描述了“金汇兑本位制”。

凯恩斯于1913年被任命为一个考察印度财政与货币的委员会秘书，并开始为其基于会士学位论文的概率论重要论著寻找出版商。然而，随着1914年8月第一次世界大战的开始，他的生活发生了显著变化。起初他基本一如既往，在Economic Journal上发表了War and the Financial System, August 1914。在1914-15学年的第一学期，他照常在剑桥履行职责，但剑桥已经是一个不同的地方了。1914年11月，他发表了一篇关于The City of London and the Bank of England的论文，但他此时写的一封信显示了战争正在产生的影响（例如见[6]）：-

对我自己来说，我绝对且彻底地感到孤寂。日复一日地看着年轻人离去，先是走向无聊与不适，然后走向屠杀，这实在令人无法忍受。

到1915年，凯恩斯在财政部工作，[2]：-

……他每天都忙于战争的经济管理。他的特别职责涵盖与盟国的关系以及节约英格兰稀缺的外汇储备。

他在财政部的职位意味着他不能再发表作品。特别是他关于概率的论著不得不搁置一旁，直到战争结束。在许多方面，这些战争岁月见证了凯恩斯处于其能力的巅峰和最具影响力之时。当然，他有信心相信自己的观点是正确的，而其他处于最高权力位置的人可能严重错误。他开始在财政部工作后不久，当时任财政大臣的Lloyd George就法国局势发表了一份声明，他在场。随后他要求发表评论，凯恩斯回答说：-

怀着最大的敬意，如果征求我的意见，我必须告诉您，我认为您的叙述是垃圾。

战争结束后，凯恩斯代表财政部参加了凡尔赛和平会议，但在1919年6月，他辞职了，理由是正在提出的德国赔款方案既不公正也不切实际。随后他又能够发表作品了，并在1919年12月以The Economic Consequences of the Peace抨击了凡尔赛和平会议的结论。在这部作品中，他毫不含糊地抨击了主要政治人物，因此他再也没有得到政府的完全信任。

1920年，凯恩斯开始准备出版他的Treatise on Probability。他发现这有点困难，因为他已经六年没有看过这部作品了。就这个数学档案而言，1921年的出版是他最重要的作品。在这部作品中，他论证概率是一种逻辑关系，因此是客观的。涉及概率关系的陈述具有独立于人们意见的真值。1926年，弗兰克·普伦普顿·拉姆齐发表了一篇论文Truth and probability，反对凯恩斯的这些论点。论文[17]考察了凯恩斯和弗兰克·普伦普顿·拉姆齐关于概率的两种观点。

凯恩斯在Treatise on Probability中讨论的其他重要思想是，概率关系仅形成一个偏序集，即两个概率不一定总是可以比较。凯恩斯还论证概率是一个基本概念，不能还原为其他概念。

凯恩斯职业生涯中另一个重要时期是20世纪30年代。这是一个失业和大萧条的时期。传统经济学无法应对所发生的非常事件，使传统经济理论束手无策。凯恩斯第一部表明他的思想正偏离传统方法的重要著作是1930年出版的A Treatise on Money。他最重要的、集其思想之大成的著作是1935-36年出版的The General Theory of Employment, Interest and Money。这部著作的两个主要观点是[2]：-

……现有的失业理论是无稽之谈。在大萧条中……工资再低也无法消除失业。因此，将失业者的困境归咎于他们是不道德的。第二个命题对失业和大萧条的起源提出了另一种解释。这集中于总需求——即消费者、企业投资者和公共机构的总支出。当总需求低时，销售和就业就会受损。当总需求高时，一切都会好起来。

到1937年，凯恩斯的健康状况开始恶化。他再也无法完全恢复健康。然而，他的专业知识如此出众，以至于在第二次世界大战期间，他被授予了财政部的一个荣誉职位。在他最后几年参与的最重要项目之一，是国际货币基金组织的建立。

关于凯恩斯的兴趣，还有几个其他方面我们应该评论。我们已经提到他对旧书的兴趣，这是他从小就有。他对现代绘画也有类似的兴趣。他的主要兴趣之一是十七和十八世纪的作品，特别是他对艾萨克·牛顿的手稿着迷。1936年，艾萨克·牛顿的论文在苏富比拍卖，通过这次拍卖它们被分散了。凯恩斯在拍卖后做出了艰苦的努力来获取这些手稿，这些努力在[18]中描述。

1942年距艾萨克·牛顿诞生已三百年[艾萨克·牛顿生于1642年圣诞节，尽管在新历中这一天成为1643年1月4日]。凯恩斯为庆祝活动写了一篇文章Newton, the Man。与大多数关于艾萨克·牛顿生平与工作的记述不同——那些记述集中于艾萨克·牛顿在数学和物理学上的成就——凯恩斯对艾萨克·牛顿关于炼金术和宗教的著作给予了同等重视。其原因在于，他的记述依据的是他所拥有的艾萨克·牛顿手稿，而这些手稿清楚向他表明，对艾萨克·牛顿来说，他在这些其他主题上的工作与他在数学物理上的工作同样重要。

1942年，凯恩斯被晋升为贵族，并在上议院获得席位，他在那里坐在自由党席位上。大约在同一时间，他成为新成立的音乐与艺术促进委员会的主席，该委员会在战争结束前更名为英国艺术委员会。凯恩斯在一次广播中描述了艺术委员会的宗旨：-

大不列颠艺术委员会的宗旨是创造一种环境，培育一种精神，培养一种舆论，提供一种激励，使艺术家和公众能够相互支持、相互依存，在这种联合中，过去在公共文明生活的伟大时代曾偶尔存在过。

在[3]中，凯恩斯被描述如下：-

凯恩斯的天才表现在他对经济科学基本原理的重要贡献上；表现在他能在关键时刻赢得公众对经济学实际应用的兴趣上；表现在他的英语散文风格上……表现在他私人谈话中闪耀的机智、智慧和广博，这使他在任何崇尚优雅讨论的时代都会成为知识界沙龙或小圈子中备受珍视的成员。

John Maynard Keynes (pronounces Canes) was born into an academic family. His father, John Nevile Keynes, was a lecturer at the University of Cambridge where he taught logic and political economy. John Nevile published Formal Logic four months after John Maynard was born. John Maynard's mother, Florence Ada Brown, was a remarkable woman who was a highly successful author, and also a great pioneer in social reform. It is worth commenting at this stage that, although John Maynard Keynes lived to the age of 63, his parents both outlived him.

At the age of seven, Keynes entered Perse School Kindergarten but he learnt more from lessons given at home. Two years later he entered St Faith's preparatory school but there was little sign at this stage that he was an exceptional pupil. As time went by he did begin to show more promise, however, and in 1894 he topped the class for the first time and received a prize for mathematics. By 1896 he was described by the headmaster as (see for example [6]):-

... head and shoulders above all the other boys in the school.

The following year Keynes sat the entrance examination for Eton and came tenth out of the twenty boys who were accepted into the school in that year. He did, however, come first equal in mathematics.

Keynes enjoyed his school days in Eton. Harrod writes in [6]:-

... Eton greatly helped his development. He found there associates who were congenial to him, youths of intellectual distinction with whom he could quickly get on to terms of intimacy on the basis of common interests.

Keynes did well at Eton winning the Senior Mathematics Prize in 1899, and again in 1900. But it was not only in mathematics that he did well; for example in 1901 he was first in mathematics, first in history, and first in the English essay. In 1902 he won a scholarship to King's College, Cambridge, in mathematics and classics. Before we leave our description of Keynes' time at Eton, we should note that it was here that he continued with one of his passions (begun at the age of twelve), namely collecting old books. He had purchased 329 old books before he entered the University of Cambridge in October 1902.

At Cambridge Keynes was tutored mathematics by E W Hobson whom he called "Hobbema". Although he studied mathematics he was no mathematical genius. His [6]:-

... logical faculty, his accuracy and his lightning speed of thought made him a thoroughly competent mathematician. He had no specific genius for mathematics; he had to take pains with his work; ... he did not seek out those abstruse regions which are a joy to the heart of the professional mathematician.

He had many interests at Cambridge beyond his academic work, spending much time with literary friends, reading, and involving himself in political activity [3]:-

He was President of the Cambridge Union [and] won the Members' English essay Prize for an essay on the political opinions of Burke ...

He put in some effort as the examinations approached to achieve a reasonable degree and he was placed twelfth Wrangler in the Mathematical Tripos of 1905, that is twelfth in the ranked list of those receiving a First Class degree.

Immediately following taking the Tripos examinations, Keynes began a serious study of economics, reading major texts on the subject. He did briefly consider taking a second Tripos examination in Economics but decided against it. After a holiday in Switzerland, he returned to Cambridge in October 1905 and attended lectures there by Alfred Marshall on economics. In August 1906 he took the Civil Service examinations and was placed second of the ten who were accepted that year. The top person had first choice of which department to enter, and chose to enter the treasury (which Keynes would have done had he come top). Keynes, with the next choice, entered the India Office.

Keynes was very unhappy when he received detailed results of the examination. He came top in logic, psychology, and the essay, while his worst subjects were mathematics and economics. He expressed disbelief at both the mathematics and economics results, and commented, probably accurately, that he knew more about economics than his examiners.

The India Office did not provide a career to Keynes' liking. He worked mostly on his own work, devoting all his spare time to the study of the theory of probability. He then submitted a dissertation on probability for a Fellowship at King's College. Johnson and Whitehead were appointed as assessors of the dissertation but, after a close contest in March 1908, Keynes was not elected. On 5 June 1908 he resigned from the India Office and, with some financial assistance from his father, went to King's with the hope that he would be successful in the Fellowship competition the following year.

Using the detailed comments on his probability dissertation by both Johnson and Whitehead, Keynes worked hard to improve it. He also discussed his work with Russell. After submitting a new version of his dissertation on probability, Keynes was elected to a Fellowship in March 1909. The reports were impressive; Whitehead wrote:-

... his axioms are good; they are simple and few and by the aid of the symbolism he deduces the whole subject from them by rigid reasoning. The very certainty and ease by which he is enabled to solve difficult questions and to detect ambiguities and errors in the work of his predecessors exemplifies and at the same time almost conceals the advance which he has made.

Russell, writing about the book which Keynes eventually published on probability, praised the work highly:-

The mathematical calculus is astonishingly powerful, considering the very restricted premises which form its foundation... The book as a whole is one which it is impossible to praise too highly and it is hoped that it will stimulate further work on a most important subject which philosophers and logicians have unduly neglected.

Keynes now taught economics at Cambridge. He published papers in statistics, in particular he attacked strongly work by Karl Pearson in letters published in 1910 and 1911 in the Journal of the Royal Statistical Society. Whether Pearson or Keynes had the better scientific case is open to question, but there is no doubt that Keynes was by far the more skilful in his style of letter writing, making Pearson (probably unfairly) look rather silly. Keynes also wrote on economics related to India and he published a major book Indian Currency and Finance in 1913. The book is considered a classic and contains a description of the "gold exchange standard".

Keynes was appointed secretary of a Commission to examine Indian Finance and Currency in 1913 and he began to seek a publisher for his major treatise on probability based on his fellowship dissertation. His life, however, changed markedly with the beginning of World War I in August 1914. At first he continued much as before, publishing War and the Financial System, August 1914 in the Economic Journal. During the first term of the academic year 1914-15 he carried out his duties as normal at Cambridge but already Cambridge was a different place. In November 1914 he published a paper on The City of London and the Bank of England but a letter he wrote at this time shows the effect that the war was having (see for example [6]):-

For myself I am absolutely and completely desolated. It is utterly unbearable to see day by day the youths going away, first to boredom and discomfort, and then to slaughter.

By 1915 Keynes was working at the Treasury where [2]:-

...he was daily concerned with the economic management of the war. His special responsibility covered relations with allies and the conservation of England's scant supply of foreign currencies.

His position at the Treasury meant that he could no longer publish. In particular his treatise on probability had to be put to one side until the war was over. In many ways these war years saw Keynes at the height of his powers and at his most influential. Certainly he had the confidence to believe his opinions were right while others in the highest positions of power could be seriously wrong. Not long after he began to work at the Treasury he was present when Lloyd George, then Chancellor of the Exchequer, made a statement regarding the position in France. He then asked for comments to which Keynes replied:-

With the utmost respect, I must, if asked for my opinion, tell you that I regard your account as rubbish.

After the war ended, Keynes represented the Treasury at the Versailles Peace Conference, but, in June 1919, he resigned on the grounds that the proposals being put forward for German reparations were both unfair and impractical. He was then in a position to publish again and he attacked the conclusions of the Versailles Peace Conference in December 1919 with The Economic Consequences of the Peace. In this work he attacked the leading political figures in no uncertain terms and as a consequence he was never fully trusted by the government again.

In 1920 Keynes began to prepare his Treatise on Probability for publication. This he found a little difficult, for he had not looked at the work for six years. Its publication in 1921 is the most important of his works as far as this mathematical archive is concerned. In this work he argues that probability is a logical relation and so it is objective. A statement involving probability relations has a truth-value independent of people's opinions. In 1926 Ramsey published a paper Truth and probability arguing against these arguments of Keynes. The paper [17] examines the two points of view of Keynes and Ramsey on probability.

Other important ideas discussed by Keynes in Treatise on Probability is that probability relations forms only a partially ordered set in the sense that two probabilities cannot necessarily always be compared. Keynes also argues that probability is a basic concept which cannot be reduced to other concepts.

Another important period of Keynes' career was during the 1930s. This was a period of unemployment and the depression. Conventional economics could not cope with the extraordinary events which took place leaving traditional economic theory with no answer. Keynes first major work which indicates the direction his ideas were taking away from the conventional approach was A Treatise on Money published in 1930. His most important work giving the culmination of his ideas was The General Theory of Employment, Interest and Money published in 1935-36. The two main messages of this work are [2]:-

... the existing theory of unemployment nonsense. In a depression ... there was no wage so low that it could eliminate unemployment. Accordingly, it was wicked to blame the unemployed for their plight. The second proposition proposed an alternative explanation about the origins of unemployment and depression. This centred upon aggregate demand - i.e. the total spending of consumers, business investors, and public agencies. When aggregate demand was low, sales and jobs suffered. When it was high, all was well.

By 1937 Keynes' health began to deteriorate. He would never be fully fit again. However, his expertise was such that he was given an honorary role in the Treasury during World War II. One of the most important projects he was involved in during his last years was the setting up of the International Monetary Fund.

There are a couple of other aspects of Keynes' interests which we should comment on. We have already mentioned his interest in old books, which he had from a very young age. He had a similar interest in modern paintings. One of his main interests was in works of the seventeenth and eighteenth centuries and in particular he was fascinated by Newton's manuscripts. In 1936 Newton's papers were sold at Sotheby's and they were dispersed by this sale. Keynes made strenuous attempts to acquire the manuscripts after the sale and these attempts are described in [18].

The year 1942 marked three hundred years from Newton's birth [Newton was born on Christmas day 1642 although this became 4 January 1643 in the new calendar]. Keynes wrote an article Newton, the Man for the celebrations. Unlike most accounts of Newton's life and work which concentrate on Newton's achievements in mathematics and physics, Keynes gave equal weight to Newton's writings on alchemy and religion. The reason for this was that he based his account on the manuscripts of Newton's which he owned and these clearly showed him that, to Newton, his work on these other topics was as important as his work on mathematical physics.

In 1942 Keynes was elevated to the peerage and took his seat in the House of Lords, where he sat on the Liberal benches. Around the same time he became chairman of the newly formed Committee for the Encouragement of Music and the Arts which, before the end of the war, was renamed the British Arts Council. Keynes described the purpose of the Arts Council in a radio broadcast:-

The purpose of the Arts Council of Great Britain is to create an environment, to breed a spirit, to cultivate an opinion, to offer a stimulus to such purpose that the artist and the public can each sustain and live on the other in that union which has occasionally existed in the past at the great ages of a communal civilised life.

In [3] Keynes is described as follows:-

Lord Keynes's genius was expressed in his important contributions to the fundamentals of economic science; in his power of winning public interest in the practical application of economics on critical occasions; in his English prose style ... in the brilliant wit, the wisdom, and the range of his private conversation, which would have him a valued member of any intellectual salon or coterie in the ages of polished discussion.