曼昆经济学原理阅读笔记

曼昆经济学原理阅读笔记（一）

曼昆的经济学定义：Economics is the study of how society manages its scarce resources。

曼昆的经济学十原理中第一条：PEOPLE FACE TRADEOFFS。这一原理的的两段经典举例：

When people are grouped into societies, they face different kinds of trade offs. The classic tradeoff is between “guns and butter.” The more we spend on national defense to protect our shores from foreign aggressors (guns), the less we can spend on consumer goods to raise our standard of living at home (butter). Also important in modern society is the tradeoff between a clean environment and a high level of income. Laws that require firms to reduce pollution raise the cost of producing goods and services. Because of the higher costs, these firms end up earning smaller profits, paying lower wages, charging higher prices, or some combination of these three. Thus, while pollution regulations give us the benefit of a cleaner environment and the improved health that comes with it, they have the cost of reducing the incomes of the firms’ owners, workers, and customers.

Another tradeoff society faces is between efficiency and equity. Efficiency means that society is getting the most it can from its scarce resources. Equity means that the benefits of those resources are distributed fairly among society’s members. In other words, efficiency refers to the size of the economic pie, and equity refers to how the pie is divided. Often, when government policies are being designed, these two goals conflict.

Efficiency 的定义：the property of society getting the most it can from its scarce resources。

Equity 的定义：the property of distributing economic prosperity fairly among the members of society。

对于社会决策者的ZF 来说，效率和平等是一对很难平衡的矛盾，容易顾此失彼。显而易见，如果一个ZF 的经济政策造成的局面是既缺少效率，又增大了不平等，那对该ZF 的评价只能是失败。ZF 是代表社会行使管理稀缺资源的主体，要提高资源利用的效率，就要牺牲平等，要兼顾平等，就会打击勤奋群体的工作效率。但至少，无论经济政策往哪一方倾斜，对于社会整体来说，是在进步。如果这些资源被有特权的特定群体所占据，则不可能出现效率，同时又不能产生平等。既无效率又无平等的社会，其崩溃是必然的。眼前正是这样一个病态的社会，决策者再不悬崖勒马，可以想见其结局。

在资源由构成社会的所有家庭和公司的联合作用或集体行为分配的社会中，出现上述矛盾的时候，是相对容易解决的，因为决策总是根据人们的利益倾向于去纠正过当的行为；而在由一个中央决策者来实施分配的时候，比如中国，就是个大大的困难了。

第二条：THE COST OF SOMETHING IS WHAT YOU GIVE UP TO GET IT

第三条：RATIONAL PEOPLE THINK AT THE MARGIN

第四条：PEOPLE RESPOND TO INCENTIVES

第五条：TRADE CAN MAKE EVERYONE BETTER OFF

第六条：MARKETS ARE USUALL Y A GOOD W AY TO ORGANIZE ECONOMIC ACTIVITY

第七条：GOVERNMENTS CAN SOMETIMES IMPROVE MARKET OUTCOMES

第八条：A COUNTRY’S STANDARD OF LIVING DEPENDS ON ITS ABILITY TO PRODUCE GOODS AND SERVICES

第九条：PRICES RISE WHEN THE GOVERNMENT PRINTS TOO MUCH MONEY

第十条：SOCIETY FACES A SHORT-RUN TRADEOFF BETWEEN INFLATION AND UNEMPLOYMENT

曼昆经济学原理阅读笔记（二）

市场经济的定义：

market economy - an economy that allocates resources through the decentralized decisions of many firms and households as they interact in markets for goods and services.

相对于计划经济体制来说，大陆的经济体制是一个处于向市场经济过渡期的怪胎。其最大的奇怪之处在于ZF 不是计划经济时期的单纯的指挥者，也不是像现代西方国家的各种经济实体联合的代言人，而是既要做指挥者，又要以普通经济实体的身份参与市场。而我们根据曼昆经济学的定义，经济学是研究社会如何管理其稀缺资源的学科，从而知道，在中国，ZF 是社会稀缺资源的管理者。那么很显然了，用一个网友的生动例子：ZF 既是球员，又是裁判，那么别人怎么玩？房地产市场的景象正是一个生动的写照。ZF 手里有土地，银行是ZF 的，而ZF 又要直接或间接的参与房地产，而众多与政府有正当或不正当关系的KFS 也依靠此势力进入市场，这样的市场不受市场的那只“看不见的手”控制，成本可以被压到远低于正常市场价格水平，利润则被通过操作成倍提升。所以ZF 发财了，ZF 是少数人之ZF，所以少数人发财了；所以KFS 暴利了，KFS 是这少数人中一分子；所以炒房者利用了这一点，也跟着赚了一把。同理可以推论石油行业，为什么国际油价上涨，我们也跟着涨，国际油价下跌，我们却不跟着跌。还可以推论交通，电信，以及一切为ZF 所控制的稀缺资源所衍生的行业。只不过房地产业现在是矛盾的集中点而已。

中国并不是市场经济，而政府此前的一系列控制房地产行业的措施全使用经济手段，比如升息，比如加税，这些政策失败了，而且甚至还加速了房价上涨，因为增加的这些成本最终要落实在价格里。就是说这种市场调节的手段，只对真正受市场规律制约的广大老百姓有效，他们为升息加税而受害，作为铁三角中的一角的KFS 并不受此手段的制约，不但不受制约还能把这一部分压力转嫁给受制约的老百姓。这也可以解释为什么人民币对美元在升值，而国内购买力在下降。解决问题的办法自然还得依靠行政手段，这只有在影响到ZF 存在的情况下才会发生。那时ZF 要做的事只有一件，丢卒保帅，即砍掉KFS 这条膀子。今天早晨看到搜狐新闻说，北京市政府已经明令禁止未封顶楼房的个人贷款，这就是行政手段，但是该文章又特别提到银行的观望，尤其国有四大银行似乎可以打打擦边球，这就是上述的球员裁判的又一个表现。不管怎么说，ZF 目前还没走到断臂的那一步。所以我遗憾他们动手控制的太早了，现在的局面还在他们的控制之内。

事情看起来很糟糕，可是每个人都的确能感受到这个国家经济仍在上升，仍然是繁荣的局面，老百姓的收入状况从总体上来看在稳步提升。这为什么？我想起亚当·斯密在《国民财富的性质和原因的研究》中提到当时英国面临的同样的局面时说过（大意），这个国家之所以在不断前进，人民生活状况不断在改善，不是因为国家政策的英明，而完全是因为该国家人民的勤劳，不仅抵消了那些失误政策的负面效应，而且能有少量盈余。而在目前的中国，老百姓的负担恐怕比十七十八世纪的英国老百姓的负担要沉重得多。

曼昆经济学原理阅读笔记（三）

第八条原理：A COUNTRY'S STANDARD OF LIVING DEPENDS ON ITS ABILITY TO PRODUCE GOODS AND SERVICES

“The relationship between productivity and living standards also has profound implications for public policy.

Productivity 定义：the amount of goods and services produced from each hour of a worke's time。

Because lower investment today means lower productivity in the future, government budget deficits are generally thought to depress growth in living standards.”

在亚洲，生产率最高的几个国家当数新加坡，韩国，日本。而韩国人跟日本人又被公认为世界上工作最为勤奋的国家。高生产率加高的工作小时数，这样的国家，如何能落后？相比之下，中国大城市的年轻人，工作也相当勤奋，就业压力和生活压力迫使他们拼命工作，北京上海深圳这些城市的发展速度也不可能不快。政策的倾斜使社会中的稀缺资源（人力是其中最为稀缺的）集中供应了这些城市，其发展速度焉能不快？使资源得到合理的分配，使

收入得到合理的分配，这是政府现在迫切要做的事。

政府增加财政预算的赤字，就是政府要从市场中多拿走一部分钱，意味着市场失去了原本可用于生产的一部分钱，这就要威胁社会生活水准的提高。如果政府拿这些钱集中做了经济上的投资，比如在北京扶持了某些高新企业，投资了固定资产，那么北京的人均生活水平将被大大提高，而外地则相反。如果政府拿这些钱砸在了水里，比如修了国家大剧院，修了世纪坛，或者拿这些钱去填补亏空或支持腐败成本，那么整个社会的生活水平都要受到影响。这可以解释为什么看起来大家都在拼命工作，GDP 也在噌噌往上涨，而我们的生活水平却没有以与之相应的节奏上涨。

第九条原理：PRICES RISE WHEN THE GOVERNMENT PRINTS TOO MUCH MONEY （政府印制了过多的钞票时会造成价格上涨）

“inflation（通货膨胀）的定义：an increase in the overall level of prices in the economy

What causes inflation? In almost all cases of large or persistent inflation, the culprit turns out to be the same—growth in the quantity of money.”

通货膨胀是抵消人们努力工作的成果的罪魁祸首，而造成通货膨胀的原因则是政府印制了过多的钞票。我们可以比较容易解释的目前通货膨胀状况的一个原因是：政府在固定资产尤其房地产也投入过分，造成了银行资金的短缺，而解决的办法则是加大钞票的印刷量。可以理解最近的关于ZF 加紧收紧银根的消息，正是要设法回收资金，减少钞票的过度印刷，从而控制通胀。这个过程不可能很快，至少要一年后，才能初步看到成效，而这还要取决于ZF 的决心和力度。

第十条原理：SOCIETY FACES A SHORT-RUN TRADEOFF BETWEEN INFLATION AND UNEMPLOYMENT

“Because prices are sticky, various types of gove rnment policy have short-run effects that differ from their long-run effects. When the government reduces the quantity of money, for instance, it reduces the amount that people spend. Lower spending, together with prices that are stuck too high, reduces the quantity of goods and services that firms sell. Lower sales, in turn, cause firms to lay off workers. Thus, the reduction in the quantity of money raises unemployment temporarily until prices have fully adjusted to the change.

The tradeoff between inflation and unemployment is only temporary, but it can last for several years. The Phillips curve is, therefore, crucial for understanding many developments in the economy. In particular, policymakers can exploit this tradeoff using various policy instruments. By changing the amount that the government spends, the amount it taxes, and the amount of money it prints, policymakers can, in the short run, influence the combination of inflation and unemployment that the economy experiences.”

在ZF 抑制通货膨胀的短期内会造成失业率的增加。当然，如果ZF 声明说他们成功实现了所谓的软着陆，那意味着通货膨胀得到抑制的同时没有造成失业率大幅增加和其他负面影响。这谈何容易。以上第二段关于ZF 抑制通胀的一些常见手段很值得玩味。

曼昆经济学原理阅读笔记（四）

第一个经济学模型：循环流成图（Circular-flow Diagram）

定义：circular-flow diagram - a visual model of the economy that shows how dollars flow through

markets among households and firms.

是资源和货币在市场中循环流动的简单图表。

第二个经济学模型：生产可能性曲线（production possibilities frontier）

定义：a graph that shows the combinations of output that the economy can possibly produce given the available factors of production and the available production technology.

微观经济学（microeconomics）：the study of how households and firms make decisions and how they interact in markets.

宏观经济学（macroeconomics）：the study of economy-wide phenomena, including inflation, unemployment, and economic growth.

曼昆关于人与人之间的相互依赖（Interdependence）关系的精妙描述：

Every day you rely on many people from around the world, most of whom you do not know, to provide you with the goods and services that you enjoy. Such interdependence is possible because people trade with one another. Those people who provide you with goods and services are not acting out of generosity or concern for your welfare. Nor is some government agency directing them to make what you want and to give it to you. Instead, people provide you and other consumers with the goods and services they produce because they get something in return.

可以以这段话为例应用到不同场合来解释我们原本以为需要在形而上层面才能解释的问题。

曼昆经济学原理阅读笔记（五）

比较优势原理

概念：

Absolute Advantage(绝对优势): the comparison among producers of a good according to their productivity.

opportunity cost(机会成本): whatever must be given up to obtain some item.

comparative advantage(比较优势): the comparison among producers of a good according to their opportunity cost.

机会成本和比较优势之间的差异造就了贸易上的收益。曼昆的例子：

SHOULD TIGER WOODS MOW HIS OWN LAWN?

Tiger Woods spends a lot of time walking around on grass. One of the most talentedgolfers of all time, he can hit a drive and sink a putt in a way that most casualgolfers only dream of doing. Most likely, he is talented at other activities too. For example, let’s imagine that Woods can mow his lawn faster than anyone else. But just because he can mow his lawn fast, does this mean he should?

To answer this question, we can use the concepts of opportunity cost and comparativeadvantage. Let’s say that Woods can mow his lawn in 2 hours. In that same2 hours, he could film a television commercial for Nike and earn $10,000. By contrast,Forrest Gump, the boy next door, can mow Woods’s lawn in 4 hours. In thatsame 4 hours, he could work at McDonald’s and earn $20.

In this example, Woods’s opportunity cost of mowing the lawn is $10,000 andForrest’s opportunity cost is $20. Woods has an absolute advantage in mowinglawns because he can do the work in less time. Yet Forrest has a comparative advantagein mowing lawns because he has the lower opportunity cost.

这算是比较优势原理在微观经济学领域应用的例子。比较优势一定是存在的，所以人们只要从事相互间的交易，就一定能从中相互得利。在自由贸易的条件下，人们的商业贸易往来，只有一方得利的情形是罕见的。这就是为什么经济学家们要一致主张自由贸易的原因，这也是为什么我们的国家要积极的参与世贸组织的谈判，争取加入WTO 的原因。加入WTO，意味着与他国贸易往来时，双方都会降低或免去进出口关税，消除贸易壁垒，从而

使商品的价格降低，最终使两国的消费者得利。而使消费者能够买到尽可能价格低的商品，则是商业的根本目的。

斯密在其《国民经济的性质和原因的研究》中以英国为例在这方面的分析很经典。比如政府的某些看似聪明的为保护本国某项商品而设置高关税，借以阻止外国廉价质优的同类商品进来，以为是保护了本国人民的利益。但实际上呢，一来这种关税抬高了商品的价格，而使消费者不得不多掏腰包，二来这种保护实际上是仅使国内生产该商品的商人得利，并且在这种情况下他们会设法持续提高高价质劣的此种商品给消费者，从而长期损害消费者的利益。

富国与穷国的贸易，在自由公平的贸易条件下，不见得是穷国受损害，相反，因为比较优势原理，是双方互惠的。伍兹和其邻居小孩的例子很好的说明了这一点。无论如何，有需求才会有贸易。如果我们国内的消费者有需要购买美国商品的需求，那么就有使这一交易自由进行的必要。可以假设，如果一个国内消费者希望购买一部手机，而在他面前只有两种选择，一种是性能差的国货，一种是性能好的外国货，那么出于保护该国货的目的而提高对外国手机的关税的做法以阻止消费者购买外国手机的行为就是对消费者的利益的侵犯。这样的行为除了使消费者多掏了腰包外，并没有给国家和社会带来什么特别的好处。因为外国手机如果和中国手机一样在中国卖，交同样的税给中国政府，那么保护国产手机企业的意义在何处？仅仅是让生产手机的商人得利！另外一种情况，国家为扶持某些被认为有前途的行业而向该行业注入资金或奖励金的做法，也与此类似，是养肥了少数人而损害了多数人利益的愚蠢行为。在市场中，资源自然会流向那些有利可图的行业，没有利益的行业资本自然不会进入，何须外力介入。政府的扶持和奖励的做法，除了使该行业的少数人获利并损害了纳税人的利益之外，没有更积极的意义。

正如现在美国政府经常祭出的对华纺织品反倾销政策，就是一个对美国消费者来说有损害的政策。因此最多也只是嚷嚷一下而已，不能长期有效地实行下去。该政策在其他政治领域的作用，才是其目标所在。但是这等于要美国民众来负担这份额外的政治成本。

曼昆的结论：

The principle of comparative advantage shows that trade can make everyone betteroff. You should now understand more fully the benefits of living in an interdependenteconomy. But having seen why interdependence is desirable, you mightnaturally ask how it is possible. How do free societies coordinate the diverse activitiesof all the people involved in their economies? What ensures that goods andservices will get from those who should be producing them to those who shouldbe consuming them?

In a world with only two people, such as the rancher and the farmer, the answeris simple: These two people can directly bargain and allocate resources betweenthemselves. In the real world with billions of people, the answer is lessobvious. We take up this issue in the next chapter, where we see that free societiesallocate resources through the market forces of supply and demand.

曼昆经济学原理阅读笔记（六）

供给和需求是市场经济运转的动力

概念：

market（市场）：a group of buyers and sellers of a particular good or service.

competitive market（竞争市场）：a market in which there are many buyers and many sellers so that each has a negligible impact on the market price.

理想的竞争市场所需的两个基本特征：

1. the goods being offered for sale are all the same, and

2. the buyers and sellers are so numerous that no single buyer or seller can influence the

market price.

市场中的买家和卖家足够多时，才能形成竞争性的市场。反之，市场中卖家只有一两个而买家甚众则必然形成垄断（monopoly），少数卖家可以有足够的力量来左右商品价格，这是最不利于买家的局面。比如中国的电信，铁路，石油行业。为什么国际市场的石油价格上涨时，国内市场会跟着上涨，而在国际市场油价下跌时，我们不会跟着下跌，原因就在这里。

law of demand（需求法则）：Other things equal, when the price of a good rises, the quantity demanded of the good falls. （其他条件相同的情况下，商品价格上涨，则对该商品的需求数量下降。）

案例分析：如何减少香烟的需求量

第一种方法：健康宣传，强制措施和禁止电视烟草广告等手段。

第二种方法：提高烟草价格（如对烟草公司增加税收）。青少年对烟草价格的变动最为敏感。

quantity supplied（供给法则）：the claim that, other things equal, the quantity supplied of a good rises when the price of the good rises.（其他条件相同的情况下，商品价格上涨时，该商品的供给数量上升。）

law of supply and demand（供需法则）：the claim that the price of any good adjusts to bring the supply and demand for that good into balance.

在理想的竞争市场（Free Market）中，众多买家和卖家的活动会自动将市场价格推向均衡价格（equilibrium price）。

曼昆经济学原理阅读笔记（七）

elasticity and its application（弹性及其应用）

考量影响需求的决定因素时，当提到买家在商品的价格降低，收入提高，替代品（substitute）的价格提高或者互补品（complement）的价格降低的情况下会有更多的对该商品的需求时，此需求分析是定性的而非定量的。要定量的分析需求量相对于其决定因素的改变所作的反应，经济学家引入了“弹性”（elasticity）概念。

elasticity：a measure of the responsiveness of quantity demanded or quantity supplied to one of its determinants.

price elasticity of demand（需求的价格弹性）：a measure of how much the quantity demanded of a good responds to a change in the price of that good, computed as the percentage change in quantity demanded divided by the percentage change in price.

影响需求的价格弹性的一些通用规则：

Necessities versus Luxuries（必需品和奢侈品）：必需品的需求弹性相对于奢侈品要低。即医疗费用增加时人们依然不得不去看病而当游艇价格上涨时会有更多的人决定不买。虽然一样东西属于必需品还是奢侈品取决于购买者的倾向，但衣食住行所需的物品通常可以认为是必需品。

Availability of Close Substitutes（最接近的替代品的可用性）：如果有充分的替代商品，那么人们很容易在一商品价格上涨时转向其替代品，此时其需求弹性较大。

Definition of the Market（市场的定义）：越宽泛定义的市场，其需求弹性越小。因为很难为一个很宽泛定义的物品比如食物找到替代品。

Time Horizon（时间范围）：在较长的时间范围内，商品有更大的需求弹性。

需求的价格弹性公式：Price elasticity of demand =(Q2 - Q1)/[(Q2 + Q1)/2]/(P2 - P1)/[(P2 + P1)/2]

曼昆希望：Throughout this book, however, we only rarely need to perform such calculations. For our purposes, what elasticity represents—the responsiveness of quantity demanded to price—is more important than how it is calculated.

当弹性值大于1 时，则需求是弹性的，此时需求数量变动的比例要大于价格；反之亦然。如果弹性值恰好等于1，则需求数量的变化比例与价格的变化比例相同，此时需求称为具有单位弹性。

弹性值为0 时，需求曲线为垂直线，此时无论价格如何变化，需求量保持不变。这是不是很像中国的房地产市场？房屋的需求量变化不是很大，但价格在飞涨。

总收入与需求的价格弹性之间的关系

total revenue（总收入）：the amount paid by buyers and received by sellers of a good, computed as the price of the good times the quantity sold.

如果需求是非弹性的，则意味着价格上涨或下降不会影响到需求量，那么涨价会增加总收入；如果需求是弹性的，则意味着价格的上涨可能大大降低需求量，那么涨价会减少总收入。评估需求是否有价格弹性的办法是根据历史数据来计算。

income elasticity of demand（需求的收入弹性）：a measure of how much the quantity demanded of a good responds to a change in consumers’ income, computed as the percentage change in quantity demanded divided by the percentage change in income.

cross-price elasticity of demand（需求的相对价格弹性）：a measure of how much the quantity demanded of one good responds to a change in the price of another good, computed as the percentage change in quantity demanded of the first good divided by the percentage change in the price of the second good.

Cross-price elasticity of demand = Percentage change in quantity demanded of good 1/Percentage change in the price of good 2

这个公式的值的正负取决于两种货物之间是互补的关系还是替代品的关系。

price elasticity of supply（供给的价格弹性）：a measure of how much the quantity supplied of a good responds to a change in the price of that good, computed as the percentage change in quantity supplied divided by the percentage change in price.

这是一个与需求的价格弹性类似的概念。

看曼昆的例子：

如果有一天农科院宣布说他们培育出了一个小麦新品种，该品种可以使小麦增产20%。那么农民们是否会欢欣鼓舞而踊跃种植此种小麦呢？

农民是否愿意种植的动力来源于该小麦是否能增加他们的收入。而对于小麦这种产品来说，市场对于其需求量的弹性很小。也就是说，在需求量固定的情况下，增加了小麦的市场供应量，必然导致小麦价格的下跌，从而农民的收入降低。当然前提是，在未采用新品种之前，农民们就已经能够生产出足够的小麦供应市场。

农业技术不断提高，则从事农业劳动的人口会越来越少，农村人口越来越少，城市人口越来越多。这是国家发展的必然过程。

曼昆经济学原理阅读笔记（八）

Supply, Demand, and Government Policies（供给、需求以及国家政策）

控制经济的两种法则：供需法则和政府制定的法则。

政府控制经济运行的两种最常见的手段，一是价格控制（Price Control），一是税收（Taxes）。

概念：

价格上限如何影响市场结果：

Price ceiling：a legal maximum on the price at which a good can be sold.

如果旨在保护消费者利益而以行政手段强行规定一价格上限的话，市场会出现两种情形：1. 该价格上限高于市场供需的平衡点，则该价格上限不起作用。2. 该价格低于市场供需的平衡点，愿意在此价格继续生产和销售的商人们不会持续增加，则供应量相对于需求量会出现短缺。消费者要么需要排队，要么需要托关系走后门，要么就干脆无法买到。这最终的结局却是对消费者的损害：When the government imposes a binding price ceiling on a competitive market, a shortage of the good arises, and sellers must ration the scarce goods among the large number of potential buyers. 供需的价格弹性曲线很直观地表明了这个现象。

价格下限如何影响市场结果：

Price floor：a legal minimum on the price at which a good can be sold.

同样的，如果政府倾向于保护商人的利益而强行制定一价格下限，那么会出现相反的两种情形：1. 该价格下限低于市场供需的平衡点，则该价格下限不起作用。2. 该价格高于市场供需的平衡点，则会吸引商人加大商品的供应量，而需求变化相对稳定的话，就会造成供应过剩（surplus）的结果。高的价格损害了购买者，而为追逐利益造成供应的过剩又损害了供应者。

加在购买者身上的税收如何影响市场结果：

tax incidence（税收负担）：the study of who bears the burden of taxation.

To sum up, the analysis yields two general lessons:

#1 Taxes discourage market activity. When a good is taxed, the quantity of the good sold is smaller in the new equilibrium.

#2 Buyers and sellers share the burden of taxes. In the new equilibrium, buyers pay more for the good, and sellers receive less.

加在出售者身上的税收如何影线市场结果：

Taxes on buyers and taxes on sellers are equivalent. In both cases, the tax places a wedge between the price that buyers pay and the price that sellers receive.

结论：A tax burden falls more heavily on the side of the market that is less elastic.

在自由的，竞争的（注意这两个限定词）市场中，价格是供需机制的动力，买家和卖家以价格为风向决定他们的行为，双方的力量最终会达致均衡的价格。那么疑问来了，政府是干什么？如果政府是市场中各种实体的联合的代言人，那么政府的职责应当是：设法维护市场的自由，公平，竞争。不自由的市场会导致商品流通的障碍，不公平的市场导致不正当的竞争，使资源不能合理分配，使一些人在正常情况下得到的利益多于另一些人。制定平等自由的市场规则，打击不正当的行为，维护市场的正常运转，是政府的职责。干预或者参与市场，都不是政府应该做的事情。

如果政府干预或者参与市场活动，那只能意味着，政府以裁判身份去当球员。作为裁判的政府，是不偏不倚的仲裁者，而作为球员的政府，就必然是作为其中的一方，他的利益与另一方是敌对的。那么既做裁判又做球员的政府就不可能再保持不偏不倚，而必然倾向于一方。这必然会破坏市场的正常运行。而受害者会是市场中正常的购买者和供给者双方。

按照通常的说法，房地产，期货，股票依次是市场中风险最大的行业。经营房地产的风

险可以从香港和日本的房地产业最近十余年的状况清楚看到。高风险意味着高利润，但无论如何它得受市场规律约束，所有有涨就必然有跌，而价格长期来看是出于与社会需求相适应的水平。但是情况在中国则完全不同，政府是最大的参与者（不知道还有多少人反对这一说法），这就使这个行业短期内的风险几乎等于零，而利润则会高到离奇。之所以风险为零，是因为政府手里掌握着相对足够的资源（资本）来玩这个游戏。我们知道，对于垄断者来说，市场是不存在风险的。但是反过来也可以说，这个行业的风险已经被无限扩大了，等于是全社会在负担这一巨大的风险，一旦爆发，就无法收拾。

最近经常能在新闻上看到的一个论调是，在政府不断加强的对房地产市场的宏观调控措施下，房地产市场会从新整合。实力较弱的小开发商要么倒下，要么被实力大的开发商并掉。这在目前情况下意味着某些非政府的小玩家在供过于求的局面下渐渐玩不起这个游戏了，而政府这个大玩家则依然有实力继续玩。加息，增税，提高存款准备金，是抑制市场热度的常规手段，但只对受市场规律制约的玩家有效。而限价，限量，限户型这些手段，是破坏市场的非常规手段，受害者依然是受市场规律制约的玩家。因为：A tax burden falls more heavily on the side of the market that is less elastic。在房地产市场中，相对于对住房有刚性需求的民众，以及资金较弱，对风险控制能力较差的小开发商来说，他们应对市场的弹性是很小的。政府在税收，在银行上的控制，倒霉的正是这些人。而这些政策加在大玩家的身上的部分，最终还是由社会全体来负担了。如果真要控制，只需政府势力退出房地产市场，让市场回归正常即可。可是这谈何容易，不仅到嘴的肉吐出来难，退出的损失还要有人来承担。

经济适用房是政府帮助穷人解决住房问题的一个手段。这个手段成功了吗？在商品房市场价格非常的情况下，经济适用房不可避免地进入市场流通，这是利益角逐的必然结果。那么政府回购后，怎么能保证再分配时，恰好把这些房子低价卖给真正的穷人呢？这是不可能的事。不使市场回归自由公平竞争的状态，回购政策只能是新一轮罪恶的温床。

曼昆经济学原理阅读笔记（九）

接上一章供给、需求与国家经济政策的案例研究：谁负担了奢侈品税？

如果我没记错，前阵子在搜狐看到新闻说，中国也要（或者已经开征？）对汽车，别墅等奢侈品征消费税。对奢侈品征税，目标看起来是指向了富人的口袋，是个劫富济贫的手段。真如此吗？看曼昆的案例：

In 1990, Congress adopted a new luxury tax on items such as yachts, private airplanes, furs, jewelry, and expensive cars. The goal of the tax was to raise revenue from those who could most easily afford to pay. Because only the rich could afford to buy such extravagances, taxing luxuries seemed a logical way of taxing the rich.

Yet, when the forces of supply and demand took over, the outcome was quite different from what Congress intended. Consider, for example, the market for yachts. The demand for yachts is quite elastic. A millionaire can easily not buy a yacht; she can use the money to buy a bigger house, take a European vacation, or leave a larger bequest to her heirs. By contrast, the supply of yachts is relatively inelastic, at least in the short run. Yacht factories are not easily converted to alternative uses, and workers who build yachts are not eager to change careers in response to changing market conditions.

Our analysis makes a clear prediction in this case. With elastic demand and inelastic supply, the burden of a tax falls largely on the suppliers. That is, a tax on yachts places a burden largely on the firms and workers who build yachts because they end up getting a lower price for their product. The workers, however, are not wealthy. Thus, the burden of a luxury tax falls more on the middle class than on the rich.

我们看到，富人是存在的，且越来越多越来越富，富人对奢侈品的需求必然形成市场。有购买者就必须有生产者销售者。那么对奢侈品征税，如果向消费者征税，那么必然造成需

求的下降。需求下降，则供过于求，从而价格下降，市场总收入下降，这样，对奢侈品所征的税有一部分就落在了生产者和销售者一方。奢侈品的生产者在市场萎缩时很难转向其他生产，在此情况下他只能降低工资或者解雇员工，来继续保持他的利益。对富人来说，他可以选择不买，他具有更大的弹性。那么受害者是谁呢？是中产阶级和低收入的工人。

由此我们可以思考另一个问题：如果国家以减轻民众负担为目标，而减少或取消对生活必需品的征税，增加非必需品的征税，是否合理？我记得斯密在他的《国民财富的性质及原因的研究》里就讨论过这个问题。

Consumers, Producers, and The Efficiency of Markets（消费者，生产者与市场效率）

这一章讨论福利经济学（Welfare Economics），即研究资源的分配如何影响经济的健康运行。步骤：

首先研究购买者和销售者从参与市场的活动中获得的利益；

然后研究社会如何使这些利益最大化。

整个的分析基于此前已经得到的结论：市场中供给和需求的平衡将使购买者和销售者的总利益最大化。

Welfare Economics: the study of how the allocation of resources affects economic well-being.

willingness to pay: the maximum amount that a buyer will pay for a good.

consumer surplus（消费者盈余）: a buyer’s willingness to pay minus the amount the buyer actually pays.

消费者的消费者盈余可以衡量消费者参与市场所获得利益。如果消费者对商品价格的心理预期（即他认为该商品的最高价值）是 100 元，那么在任何低于该价格的价位买到该商品，都可获得消费者盈余。价格越低，则此盈余越多，消费者从中获得的利益越多。因此，在正常的市场中，消费者盈余的确反映了经济的运行状况。曼昆的需求曲线很好的说明了这个问题。

Producer Surplus（生产者盈余）：the amount a seller is paid for a good minus the seller’s cost.

cost: the value of everything a seller must give up to produce a good.

商品的价格高于其成本，是销售者卖出货物的根本动力。价格高于商品成本越多，则销售者从中获得的利益越多。由于消费者盈余和生产者盈余是相对的两个方向，且二者密切相关，所以降两者结合起来，是研究经济运行状况的好办法。

Market Efficiency

efficiency: the property of a resource allocation of maximizing the total surplus received by all members of society.

equity: the fairness of the distribution of well-being among the members of society.

Total surplus = Value to buyers - Amount paid by buyers + Amount received by sellers - Cost to sellers = Value to buyers - Cost to sellers

在只考虑效率的情况下，总盈余越大，则表示资源分配的效率越大。而考虑公平的话，情况要复杂得多。曼昆的举例：在市场中人们从贸易上获得的利益如同一个蛋糕，需要分配给市场的各个参与者。提高效率就是如何把蛋糕做大，提高公平就是如何把蛋糕分得更合理。

EVALUATING THE MARKET EQUILIBRIUM（评估市场均衡）

1. Free markets allocate the supply of goods to the buyers who value them most highly, as measured by their willingness to pay.

2. Free markets allocate the demand for goods to the sellers who can produce them at least cost.

Thus, given the quantity produced and sold in a market equilibrium, the social planner cannot increase economic well-being by changing the allocation of consumption among buyers or the allocation of production among sellers.

But can the social planner raise total economic well-being by increasing or decreasing the quantity of the good? The answer is no, as stated in this third insight about market outcomes:

3. Free markets produce the quantity of goods that maximizes the sum of consumer and producer surplus.

所以曼昆的结论，当然是在自由市场中，是：

The job of the benevolent social planner is, therefore, very easy: He can leave the market outcome just as he finds it. This policy of leaving well enough alone goes by the French expression laissez-faire, which literally translated means “allow them to do”.

所以说应该把增加市场总产出的职责交给斯密的那只“看不见的手”。

在这章中曼昆的两个重要假设，这是本章讨论的立足点：

First, our analysis assumed that markets are perfectly competitive. In the world, however, competition is sometimes far from perfect.In some markets, a single buyer or seller (or a small group of them) may be able to control market prices.

This ability to influence prices is called market power. Market power can cause markets to be inefficient because it keeps the price and quantity away from the equilibrium of supply and demand.

Second, our analysis assumed that the outcome in a market matters only to the buyers and sellers in that market. Yet, in the world, the decisions of buyers and sellers sometimes affect people who are not participants in the market at all. Pollution is the classic example of a market outcome that affects people not in the market. Such side effects, called externalities, cause welfare in a market to depend on more than just the value to the buyers and the cost to the sellers. Because buyers and sellers do not take these side effects into account when deciding how much to consume and produce, the equilibrium in a market can be inefficient from the standpoint of society as a whole.

在多数情况下，那只“看不见的手”是工作得很好的。