Government microeconomic intervention
A-Level Economics Topic 3 14:54 English narration · English + 中文 subtitles burned in
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Transcript
This power station makes electricity, and you pay for the electricity.
这座电厂在发电，而你为电付钱。
But the people living beside it breathe the smoke, and they never agreed to anything.
但住在旁边的人要吸进烟尘， 他们却从未同意过任何事。
Now look again: in one city, great wealth stands beside real poverty.
再看第二张图：在同一座城市里， 巨大的财富与真实的贫困并排而立。
Markets are powerful, but not always efficient, and not always fair.
市场很强大，但并不总是有效率，也并不总是公平。
Watch what just happened.
看看刚才发生了什么。
A buyer and a seller agreed a price, and both were happy.
买方和卖方谈好了一个价格，双方都很满意。
But a third party, a family living nearby, breathed the smoke.
但有一个第三方——住在附近的一家人——吸进了烟尘。
They were never part of the deal, so their cost never reached the price.
他们从来不是这笔交易的一部分，所以他们承担的成本没有进入价格。
That is market failure: the price is too low, and the factory makes too much.
这就是市场失灵：价格太低，工厂就生产得太多。
Here is the same idea drawn as three boxes.
同一个想法，这里画成三个方框。
Buyer and seller make a deal and both are happy.
买方和卖方做成一笔交易，双方都满意。
A dashed arrow runs down to a third party nearby.
一条虚线箭头向下指向附近的第三方。
That arrow is pollution — a cost dumped on people who never signed the deal.
那条箭头就是污染—— 成本被甩给了从未在合同上签字的人。
An externality is exactly this: a cost or a benefit that lands on someone outside the market.
外部性正是这个意思： 成本或收益落在市场之外的人身上。
When the cost is ignored, the price understates the true cost to society.
当成本被忽略时， 价格就低估了社会真正付出的成本。
Market failure means resources are not allocated efficiently — too much of one good, too little of another.
市场失灵是指资源没有得到有效率的配置——某种商品生产得太多，另一种又太少。
Five reasons matter.
有五个原因要记住。
Externalities, where costs or benefits land on other people.
第一，外部性，成本或收益落在别人身上。
Public goods, which nobody will pay for.
第二，公共物品，没有人愿意为它付钱。
Merit and demerit goods, which people misjudge.
第三，优值品与劣值品，人们会误判它们。
Monopoly power, where one firm cuts output and raises price.
第四，垄断势力，一家企业减少产量并抬高价格。
And inequality, with asymmetric information.
第五，不平等，以及信息不对称。
Here is the diagram the exam wants.
这就是考试要考的图。
Demand shows the benefit to society.
需求曲线表示社会得到的收益。
The private cost curve counts only what the firm pays, so the free market settles where that curve meets demand.
私人成本曲线只算企业自己付出的成本，所以自由市场停在这条曲线与需求相交的地方。
Now add the pollution.
现在把污染加进来。
The social cost curve lies above it, and society's best quantity is smaller.
社会成本曲线在它上方，社会最优的数量更小。
That gap is the welfare loss.
两者之间的差距就是福利损失。
Freeze the labels.
把标注停住看清。
Demand is also social benefit.
需求也是社会收益。
Private cost is the supply the firm actually faces.
私人成本是企业真正面对的供给。
Social cost sits above it by the external cost of pollution.
社会成本比它高，高出的部分就是污染的外部成本。
The free market stops where demand meets private cost — that is market quantity, too high.
自由市场停在需求与私人成本相交处——那就是市场数量，偏高了。
Society's best point is where demand meets social cost — a smaller quantity.
社会最优点在需求与社会成本相交处——数量更小。
The purple triangle between those two points is the welfare loss from over-production.
两点之间的紫色三角形，就是过度生产造成的福利损失。
Write social cost above private cost, then shade the triangle.
先写清社会成本在私人成本之上，再把三角形涂出来。
Turn it around.
反过来看。
With a positive externality the benefit spills onto other people, so social benefit lies above private benefit.
正外部性是指收益溢出到其他人身上， 所以社会收益在私人收益之上。
Vaccination is the classic case: your injection protects your neighbours too.
疫苗接种是最典型的例子：你打了针，也保护了邻居。
Buyers count only their own benefit, so the market quantity is too small, and the welfare loss comes from producing too little.
买者只算自己的收益，因此市场数量太小， 而福利损失来自生产得太少。
Two more failures belong on the list.
还有两种失灵应该列进来。
Monopoly power: one firm dominates a market, and a firm with that power can cut output and raise the price above the competitive level.
垄断势力：一家企业主导了市场， 而拥有这种势力的企业可以减少产量、把价格抬到竞争水平之上。
That wastes resources and harms consumers.
这既浪费资源，也损害消费者。
And inequality with asymmetric information.
再就是不平等和信息不对称。
The market rewards people who OWN resources, so it can produce great inequality, leaving some people with too little to live on.
市场奖励的是拥有资源的人， 所以它会造成巨大的不平等，让一些人连维持生活都不够。
Asymmetric information is when one side of a deal knows more than the other — a used-car seller knows the faults and the buyer does not — which leads to poor decisions and unfair deals.
信息不对称是指交易的一方比另一方知道得更多—— 二手车卖家知道车有哪些毛病，而买家不知道—— 这会导致错误的决策和不公平的交易。
Some goods the market will not supply at all.
有些商品市场根本不会提供。
Think of a street light.
想一想一盏路灯。
It has non-rivalry: my use leaves no less for you.
它具有非竞争性：我用它，并不会让你少用一点。
And non-excludability: nobody can shut out a person who did not pay.
它还具有非排他性： 没有付钱的人也无法被排除在外。
So each person waits for a neighbour to pay.
于是每个人都等着邻居去付钱。
That is the free-rider problem — nobody pays, and the light is never built.
这就是搭便车问题——没有人付钱，路灯永远建不起来。
Only the government will provide it.
只有政府会提供它。
Two goods people misjudge.
有两类商品人们会判断错。
A merit good, like education, does you more good than you realise, so too little is bought.
优值品，比如教育，对你的好处比你以为的更大， 所以买得太少。
A demerit good, like cigarettes, does you more harm than you realise, so too much is bought.
劣值品，比如香烟，对你的害处比你以为的更大， 所以买得太多。
The cause is information failure: people misjudge the true benefit or the true harm.
原因是信息失灵： 人们误判了真正的收益或真正的危害。
Cigarettes are the exam's favourite demerit good.
香烟是考试最爱考的劣值品。
People under-weight the long harm to their own health, so too many packets are bought.
人们低估它对自身健康的长期伤害， 所以买得太多。
Smoking also dumps a cost on others through second-hand smoke — a negative externality on top.
吸烟还通过二手烟把成本甩给别人—— 这又叠加了负外部性。
So governments tax tobacco heavily: to raise the price, cut consumption, and make buyers face more of the true cost.
于是政府对烟草重税：抬高价格、减少消费， 让买者承担更多真正的成本。
Whether that works depends on how inelastic demand really is — we will test that in a moment.
这是否有效，取决于需求到底有多缺乏弹性—— 我们稍后会检验这一点。
The first tool is an indirect tax, a tax on spending.
第一个工具是间接税，也就是对支出征税。
It raises the firm's costs, so supply shifts left.
它抬高了企业的成本， 所以供给曲线左移。
The price rises and the quantity falls.
价格上升，数量下降。
Look at the two labels on the left: the tax is split.
看图左边的两个标注： 这笔税被分摊了。
Part is paid by consumers in the higher price, and the rest is absorbed by producers.
一部分由消费者以更高的价格承担， 其余部分由生产者吸收。
Who pays more is the incidence.
谁承担得更多，就叫做税收归宿。
Who really pays?
到底是谁真正付了税？
Elasticity decides.
由弹性决定。
On the left, demand is inelastic: steep, because buyers cannot easily stop buying.
左边，需求缺乏弹性：曲线很陡， 因为买者不容易停止购买。
On the right, demand is elastic: flat, because buyers can walk away.
右边，需求富有弹性：曲线很平， 因为买者可以走开。
Now the same tax on both markets.
现在给两个市场征同样的税。
On the steep side the price jumps, so consumers bear most of the incidence.
在陡的那一边，价格跳得很高， 所以消费者承担了大部分税。
On the flat side it hardly moves, so producers pay most of it.
在平的那一边，价格几乎不动， 所以生产者承担了大部分。
The incidence falls on whichever side is less able to respond — the more inelastic one always carries more.
越缺乏弹性的一方，承担得越多。
A subsidy is the mirror image: a payment to producers.
补贴正好相反：它是付给生产者的钱。
It lowers their costs, so supply shifts right.
它降低了生产者的成本， 所以供给曲线右移。
The price falls and the quantity rises.
价格下降，数量上升。
Governments subsidise merit goods and goods with positive externalities — buses, vaccines, training — where the market makes too little.
政府会补贴优值品， 以及具有正外部性的商品——公交、疫苗、职业培训—— 也就是市场生产得太少的地方。
Hold the two tools side by side.
把两种工具并排放好。
An indirect tax shifts supply left: price up, quantity down.
间接税使供给左移：价格上升，数量下降。
Use it when the market makes too much — demerit goods and negative externalities.
用在市场生产过多的地方——劣值品和负外部性。
A subsidy shifts supply right: price down, quantity up.
补贴使供给右移：价格下降，数量上升。
Use it when the market makes too little — merit goods and positive externalities.
用在市场生产过少的地方——优值品和正外部性。
Same diagram shape, opposite direction.
图的形状相同，方向相反。
In the exam, say which failure you are fixing before you draw the shift.
考试时，先说清你在纠正哪一种失灵，再画移动。
Now the government fixes the price itself.
现在政府直接规定价格。
On the left, a maximum price is a legal top price set below equilibrium — rent control is the classic case — so buyers want more than firms supply, and that gap is a shortage.
左边，最高限价是法定的价格上限，设在均衡价格之下—— 房租管制就是典型例子——于是买者想要的多于企业愿意供给的， 这个缺口就是短缺。
On the right, a minimum price sits above equilibrium, like a minimum wage, so quantity supplied is greater than quantity demanded: excess supply.
右边，最低限价设在均衡价格之上，比如最低工资， 于是供给量大于需求量，出现超额供给。
Below for a maximum, above for a minimum.
最高限价在下面，最低限价在上面。
Watch a maximum price work in motion.
看最高限价在动态中如何起作用。
The legal ceiling sits below the free market price.
法定上限设在自由市场价格之下。
Quantity demanded jumps up; quantity supplied falls.
需求量跳升，供给量下降。
The gap that opens between them is the shortage.
两者之间拉开的缺口就是短缺。
Rent control is the usual story: more tenants want a flat at the low rent, landlords offer fewer flats, and queues or waiting lists appear.
房租管制是常见例子：低租金下更多租客想租房，房东却少放盘， 于是出现排队或轮候名单。
Below equilibrium means a shortage — never forget that direction.
低于均衡就意味着短缺——方向绝不能记反。
One rule saves marks.
有一条规则能保住分数。
A maximum price must sit below equilibrium, or it does nothing.
最高限价必须设在均衡之下，否则不起作用。
Below means quantity demanded exceeds quantity supplied — shortage.
在下方意味着需求量大于供给量——短缺。
A minimum price must sit above equilibrium.
最低限价必须设在均衡之上。
Above means quantity supplied exceeds quantity demanded — surplus, or excess supply.
在上方意味着供给量大于需求量—— 过剩，也就是超额供给。
Minimum wage is the standard example of a floor; rent control is the standard example of a ceiling.
最低工资是下限的标准例子； 房租管制是上限的标准例子。
Below for a maximum. Above for a minimum.
最高限价在下，最低限价在上。
Farm prices swing wildly, so governments use a buffer stock.
农产品价格波动很大，所以政府会使用缓冲库存。
When the price falls to the floor, the government buys the crop and stores it, holding the price up.
当价格跌到下限时， 政府买入并储存这些农产品，把价格托住。
When the price rises to the ceiling, it sells from the store, bringing the price down.
当价格涨到上限时， 政府从库存中卖出，把价格压下来。
The price stays inside a band.
价格就被保持在一个区间之内。
But storage costs money.
但是仓储要花钱。
Now judge the buffer stock.
现在来评价缓冲库存。
It can steady farm incomes and protect consumers from wild spikes.
它能稳住农户收入，也能保护消费者免受剧烈涨价。
But storage costs money every year the stock sits idle, and some crops spoil.
但仓储每年都要花钱，库存闲置也要花钱，有些作物还会变质。
If the floor is set too high, the government buys huge piles that never sell.
如果下限定得太高，政府会买进永远卖不掉的大堆库存。
If the ceiling is set too low, the store empties on the first bad harvest.
如果上限定得太低，一次歉收就会把仓库清空。
So the policy works only when the band is realistic and the storage budget is honest — classic evaluation material.
所以只有当区间现实、仓储预算诚实的时候，这项政策才有效—— 这是典型的评价材料。
Three more tools.
还有三个工具。
Regulation is rules and laws: bans, age limits, safety and pollution standards.
管制就是规则和法律：禁令、年龄限制、安全标准和排污标准。
State provision means the government supplies the good itself, free at the point of use.
政府提供是指政府自己供给这种商品，使用时免费。
Tradable permits cap total pollution and let firms trade the right to pollute, so the cap is met at the lowest cost.
可交易许可证给污染总量设一个上限，并允许企业买卖排污权， 这样就能以最低的成本达到这个上限。
Intervention can also make things worse.
但干预也可能把事情变得更糟。
Government failure is when the policy itself misallocates resources.
政府失灵，就是政策本身造成了资源错配。
Three more tools, and the third is the clever one.
还有三种工具，而第三种是巧妙的那一个。
Regulation means rules and laws — bans, age limits, safety standards, pollution limits.
管制指的是规则和法律——禁令、年龄限制、安全标准、排污上限。
State provision means the government supplies the good directly, often free at the point of use: public goods, and merit goods like schools and hospitals.
政府提供指的是政府直接供应这种物品，往往在使用时是免费的： 公共物品，以及学校和医院这类优效品。
And tradable permits set a total CAP on pollution and hand out permits to pollute.
而可交易许可证给污染设定一个总量上限，并把排污许可发下去。
Firms that cut pollution cheaply can sell their spare permits to firms for which cutting is expensive.
减排成本低的企业可以把用不完的许可卖给减排成本高的企业。
So total pollution is capped at a level you choose, and the cuts happen wherever they are cheapest — which is more than a plain regulation can do.
于是污染总量被限制在你选定的水平上， 而减排发生在成本最低的地方——这是单纯的管制做不到的。
Intervention does not always help, and an evaluation question expects you to say so.
干预并不总是有帮助，而评价类题目要求你把这一点说出来。
Government failure is when the government's action makes the use of resources WORSE, not better.
政府失灵是指政府的行动使资源的使用变得更糟，而不是更好。
Four common causes.
有四种常见原因。
Poor information, so the government sets the wrong tax or the wrong subsidy — it cannot measure the external cost precisely.
信息不充分，于是政府定错了税率或补贴——它无法精确度量外部成本。
The cost of running the policy itself, which uses resources too.
政策本身的执行成本，这同样要耗费资源。
Unintended results: a maximum price is the standard example, because it can create an illegal black market.
意料之外的后果：最高限价是标准的例子，因为它会催生非法的黑市。
And decisions made for political reasons rather than for efficiency.
以及出于政治考虑而非效率考虑作出的决定。
Name the cause, not just the phrase.
要说出具体的原因，而不只是搬出这个词。
A real exam question.
来看一道真实的考题。
A government puts a two pound tax on every packet of cigarettes, and demand is very price inelastic.
政府对每包香烟征收两英镑的税， 而香烟的需求非常缺乏弹性。 到底谁真正付了这笔税？
Who really pays, and does the policy work?
这项政策有效吗？ 先暂停，自己试一试。
Pause and try it.
从弹性入手。
Start from elasticity. Smokers keep buying almost the same quantity, so producers pass the tax on.
吸烟者购买的数量几乎不变， 所以生产者可以把税转嫁出去。
So the incidence falls on consumers: the price rises about one pound eighty, and producers absorb twenty pence.
于是税收归宿主要落在消费者身上： 价格上涨大约一英镑八十便士，生产者只吸收二十便士。 现在分别判断两个目标。
Now judge each aim. As a revenue raiser it succeeds, because quantity barely falls.
作为筹集收入的手段，它是成功的，因为数量几乎不下降。
As a way to cut smoking it largely fails, for the same reason.
作为减少吸烟的手段，它基本上失败了，原因完全相同。
And it is regressive: the poor spend a larger share of their income.
而且它是累退的：穷人为它花掉的收入比例更大。
A different exam question.
换一道考题。
A factory pollutes.
一家工厂在排污。
How can an indirect tax correct that market failure?
间接税怎样纠正这种市场失灵？
Pollution is a negative externality, so social cost lies above private cost and the market over-produces.
污染是负外部性，所以社会成本在私人成本之上，市场生产过多。
Set the tax equal to the marginal external cost at the social optimum — not at the free-market quantity.
把税额定在社会最优点上的边际外部成本——而不是自由市场数量上的。
Supply shifts left.
供给左移。
Private cost rises to match social cost.
私人成本被抬到与社会成本一致。
The firm internalises the externality, and output falls toward the social optimum.
企业把外部性内部化， 产量向着社会最优下降。
The polluter pays.
污染者付费。
Name the size of the tax: equal to the external cost at the optimum.
要说出税额的大小：等于最优点上的外部成本。
Two words the exam loves to separate.
有两个词，考试最喜欢考它们的区别。
Income is a flow: money received over a period — wages, rent, interest.
收入是流量：在一段时间里得到的钱—— 工资、租金、利息。
Wealth is a stock: the value of everything owned at one moment — a house, shares, savings.
财富是存量：在某一时刻所拥有的全部东西的价值—— 房子、股票、储蓄。
The two are linked.
这两者是相连的。
Saving from income builds wealth, and wealth then earns more income.
把收入存下来会积累成财富， 而财富又会带来更多收入。
So a small gap in income grows into a far larger gap in wealth.
所以收入上一个小小的差距， 会变成财富上一个大得多的差距。
Income and wealth are linked in both directions, and saying so is worth a mark.
收入和财富在两个方向上相互关联，而把这一点说出来是值得一分的。
Wealth produces income — savings earn interest, a house earns rent — and income can be saved to build wealth.
财富产生收入——储蓄有利息，房子有租金—— 而收入又可以储蓄起来积累成财富。
So an advantage in one becomes an advantage in the other, which is why inequality compounds over time.
所以一方面的优势会变成另一方面的优势， 这正是不平等会随时间不断累积的原因。
As for the causes: differences in skills and therefore wages; the ownership of wealth itself; inheritance, which passes that ownership on without any work; and unemployment, which removes income entirely.
至于成因：技能的差异，因而工资的差异；财富所有权本身； 遗产继承，它不需要任何劳动就把这种所有权传下去； 以及失业，它把收入完全切断。
Three tools.
有三种工具。
A progressive tax takes a larger PERCENTAGE from higher incomes than from lower ones — note percentage, not amount, because a flat tax already takes a larger amount and is not progressive.
累进税从高收入中拿走的百分比高于从低收入中拿走的—— 注意是百分比，不是金额，因为单一税率已经拿走了更多的金额，但它不是累进的。
Benefits, also called transfer payments, are money paid by the government to the poor, the old and the unemployed.
福利金，也叫转移支付，是政府付给穷人、老人和失业者的钱。
And state provision of free services like education and health care raises the REAL living standards of poorer people even without giving them money.
而政府提供教育、医疗这类免费服务， 即使不给钱也能提高较贫困人群的实际生活水平。
Together these achieve redistribution.
这三者共同实现了再分配。
But finish with the trade-off, because that is the evaluation mark: very high taxes and large benefits may weaken the incentive to work and to invest.
但最后要说出那个取舍，因为那才是评价的得分点： 过高的税收和过大的福利，可能削弱工作和投资的积极性。
How does a government narrow the gap?
政府怎样缩小这个差距？
A progressive tax takes a larger percentage from higher incomes.
累进税对更高的收入按更大的百分比征税。
Benefits, also called transfer payments, pay money to the poor, the old and the unemployed.
福利金，也叫转移支付，把钱发给穷人、老年人和失业者。
Free schools and hospitals raise the living standards of poorer households.
免费的学校和医院提高了较贫困家庭的实际生活水平。
Together that is redistribution.
这些加在一起就是再分配。
But always give the trade-off: high taxes and large benefits may weaken the incentive to work.
但一定要写出取舍： 过高的税和过多的福利，可能削弱人们工作的激励。
Four marks students throw away.
四个学生常丢的分。
First, define market failure as a misallocation of resources, then name the type.
第一，把市场失灵定义为资源错配，然后说出是哪一类。
Second, on an externality diagram mark where private and social diverge, and shade the welfare loss.
第二，在外部性图上标出私人与社会的分离，并把福利损失涂出来。
Third, tie incidence to elasticity: the side that cannot respond carries more.
第三，把税收归宿和弹性联系起来：不能作出反应的一方承担得更多。
Fourth, evaluate every policy with one advantage and one drawback.
第四，对给出的每一项政策，都写一个优点和一个缺点。