Government macroeconomic intervention (A Level)
A-Level Economics Topic 10 7:13 English narration · English + 中文 subtitles burned in
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Inside a building like this one, a small committee meets and changes a single number: the interest rate.
在这样一栋大楼里，一个小小的委员会开会，只改动一个数字：利率。
Nothing is built. Nothing is bought.
没有建造什么，也没有购买什么。
Yet within days, banks, firms and families across the country begin to move — and so do millions of jobs and prices.
但几天之内，全国的银行、企业和家庭就开始行动—— 数以百万计的工作和价格也随之改变。
A government is judged on four things at once: growth, jobs, steady prices, and trade with the rest of the world.
政府同时要对四件事负责：增长、就业、物价稳定，以及与世界其他地区的贸易。
Now push aggregate demand up — spend more, or cut the interest rate.
现在把总需求推上去——多支出，或者降低利率。
Two of them get better: output grows, and more people find work.
其中两项变好了：产出增长，更多人找到工作。
But the other two get worse: prices rise faster, and the country pulls in imports.
但另外两项变差了：物价上涨更快，国家买进更多进口品。
<slow>One push.
一次推动，四个目标。
Four objectives.</slow> They never all move together.
它们从来不会一起变好。
Today: the four objectives a government aims at, and how each one is measured. Why they pull against each other. And how well fiscal, monetary and supply-side policy really work — including the two limits the examiner loves.
今天我们要讲：政府追求的四个目标，以及每一个是怎样衡量的； 它们为什么互相拉扯；以及财政政策、货币政策和供给侧政策到底有多有效—— 包括考官最爱考的两个局限。
Let's begin.
让我们开始吧。
Start with the four macroeconomic objectives.
先看目标。
Economic growth is measured by the percentage change in real GDP.
经济增长用实际国内生产总值的百分比变化来衡量。
Price stability means low inflation, measured by the percentage change in the consumer price index.
物价稳定指的是低通货膨胀，用消费者价格指数的百分比变化来衡量。
Full employment is measured by the unemployment rate.
充分就业用失业率来衡量。
And balance of payments stability, by the current account balance.
国际收支稳定则用经常账户余额来衡量。
In the exam, name the objective and its measure.
考试时，要写出目标和它的衡量方式。
Both earn marks.
两者都有分。
A quick recall of the toolkit.
先快速回忆一下工具箱。
Fiscal policy is spending and taxes.
财政政策是支出和税收。
Monetary policy is the interest rate and the money supply.
货币政策是利率和货币供给。
Both act on aggregate demand, so they are fast but inflationary.
两者都作用于总需求，所以见效快，但容易推高物价。
Supply-side policy acts on capacity instead: slow, but lasting.
供给侧政策作用的是生产能力： 慢，但持久。
Today we ask a harder question — how well do they actually work?
今天我们问一个更难的问题——它们到底有多有效？
The objectives are interrelated: reach one, and you often move another. The exam names the conflicts.
这些目标是相互关联的：实现了一个，往往就动了另一个。
Unemployment versus inflation: lower unemployment tends to bring higher inflation.
失业下降往往带来更高的通货膨胀。 增长加快同样带来更高的通货膨胀。
Growth versus inflation: faster growth brings higher inflation too. Growth versus the balance of payments: faster growth worsens the current account, because richer households buy more imports. Growth versus the environment: more output usually means more pollution.
增长加快还会使经常账户恶化，因为更富裕的家庭买进更多进口品。
And growth versus equality, because the gains rarely reach everyone equally.
而增长加快通常还意味着更多污染。
So a government must choose which goal to protect.
所以政府必须选择保住哪一个目标。
And the links run both ways: a policy aimed at one objective always lands on the others too.
而且这种联系是双向的：针对一个目标的政策，也一定会落到其他目标上。
That is what interrelated means.
这就是"相互关联"的含义。
The trade-off between unemployment and inflation has a name: the Phillips curve.
失业与通货膨胀之间的取舍有一个名字：菲利普斯曲线。
In the short run it slopes downward — buy lower unemployment, and you pay in higher inflation.
在短期它向下倾斜——买到更低的失业，就要用更高的通货膨胀去付账。
But in the long run it is vertical, standing at the natural rate of unemployment.
但在长期它是垂直的，立在自然失业率上。
Demand policy moves you along the short-run curve; it cannot hold unemployment below the natural rate for ever.
需求政策只能让你沿着短期曲线移动， 无法让失业永远低于自然率。
Only supply-side policy shifts that vertical line.
只有供给侧政策才能移动那条垂直线。
So how well does each tool work?
那么每种工具到底有多有效？
Fiscal policy is powerful: it acts directly on demand, and it can be aimed at one region or one group.
财政政策很有力：它直接作用于需求， 而且可以对准某个地区或某群人。
But it has three weaknesses.
但它有三个弱点。
First, time lags — a budget is set once a year, and the spending takes months to arrive.
第一，时滞——预算一年才定一次， 支出要过几个月才到位。
Second, a large deficit adds to the national debt, serviced for years afterwards.
第二，巨额赤字会增加国债，以后多年都要还本付息。
Third, crowding out.
第三，挤出效应。
Strong medicine, then — but slow, and it can squeeze the private sector.
所以它是猛药——但见效慢，而且可能挤压私人部门。
Here is crowding out, drawn on the market for loanable funds.
这就是挤出效应，画在可贷资金市场上。
The government borrows heavily, so the demand for funds shifts to the right.
政府大量借款，所以对资金的需求向右移动。
The interest rate is bid up.
利率被抬高。
And at that dearer rate, private firms borrow and invest less.
在更贵的利率下，私人企业借得更少，投资也更少。
Government spending has partly replaced private investment instead of adding to it, so the boost to demand is smaller than hoped.
政府支出部分地取代了私人投资，而不是叠加在它之上，所以对需求的拉动比预期的小。
Taxes have a limit of their own.
税收本身也有极限。
The Laffer curve plots tax revenue against the tax rate.
拉弗曲线画的是税收收入对税率的关系。
At a rate of zero, revenue is zero.
税率为零时，收入为零。
At a hundred per cent, nobody works in the taxed economy, so revenue is zero again.
税率为百分之百时，没人会在被征税的经济里工作，所以收入又是零。
Between them lies the rate that raises the most revenue.
在两者之间，有一个能带来最多收入的税率。
Above it, higher taxes discourage work and invite avoidance, and revenue falls.
超过它， 更高的税会打击工作意愿、诱发避税，收入反而下降。
A government cannot simply tax its way out of a deficit.
政府不能光靠加税来摆脱赤字。
Now the other two tools.
现在看另外两种工具。
Monetary policy is flexible: the rate can be changed at any meeting.
货币政策很灵活：利率在任何一次会议上都可以改。
But it works through a long chain, so the full effect can take two years — and in a deep slump the chain breaks, because frightened firms and families will not borrow however low the rate goes.
但它通过一条很长的链条起作用，所以完整效果可能要两年—— 而且在深度衰退中这条链会断，因为受惊的企业和家庭无论利率多低都不会借款。
Supply-side policy is the one tool with no trade-off: it raises growth and cuts inflation together.
供给侧政策是唯一没有取舍的工具：它同时提高增长、压低通胀。
But it is slow, it is expensive, and some measures, such as cutting benefits, widen inequality.
但它慢，它贵，而且有些措施（比如削减福利）会扩大不平等。
Now put it all together in a full exam answer.
现在做一道完整的考试答题。
A government cuts interest rates to reduce unemployment.
政府降低利率以减少失业。
Which other objective is put at risk, and why?
哪一个其他目标会受到威胁，为什么？
Step one: borrowing is cheaper and saving less rewarding, so consumption and investment rise.
第一步：借款更便宜，储蓄回报更低，所以消费和投资上升。
Step two: aggregate demand rises, output rises, firms take on more workers — unemployment falls, as intended.
第二步：总需求上升，产出上升，企业雇佣更多工人——失业下降，正如所愿。
Step three: near full capacity, that same demand pulls prices up, so inflation rises.
第三步：接近充分产能时，同样的需求把物价拉高，所以通货膨胀上升。
Step four: richer households buy more imports, so the current account worsens.
第四步：更富裕的家庭买进更多进口品，所以经常账户恶化。
The objective at risk is low inflation, through the short-run Phillips curve trade-off.
受到威胁的目标是低通货膨胀，机制是短期菲利普斯曲线的取舍。
And here is the evaluation the examiner wants on policy effectiveness: only supply-side policy improves both at once.
而考官想要的评价是：只有供给侧政策能同时改善这两者。
Put it together.
把它们放到一起看。
No single policy hits every target: the objectives conflict, the effects arrive late, and the future is uncertain.
没有哪一种政策能同时击中每一个目标： 目标彼此冲突，效果来得晚，未来也不确定。
So governments mix them.
所以政府把它们组合起来。
Demand-side policy — fiscal and monetary — for the short term.
需求侧政策——财政与货币——用在短期。
Supply-side policy for the long term, to raise capacity.
供给侧政策用在长期，提高生产能力。
And they accept that some goals must be traded away.
同时他们接受：有些目标必须被让出去。
Three things that turn a good answer into a top one.
有三件事能把一份好答案变成顶尖答案。
First, show the trade-off — name both objectives and the mechanism that links them.
第一，展示取舍——写出两个目标， 以及把它们连起来的机制。
Second, evaluate: judge a policy by its time lags, by expectations, and by the state of the economy.
第二，要评价：用时滞、预期和经济当前状态来判断一项政策。
A rate cut in a boom is not a rate cut in a slump.
繁荣时的降息，和衰退时的降息不是一回事。
Third, match the tool to the target, then say what conflict it creates.
第三，把工具对准目标， 再说出它会带来什么冲突。
So: objectives conflict — a gain on one costs another.
所以：目标彼此冲突，得到一个就要失去另一个。
Government borrowing raises the interest rate and crowds out private investment.
政府借款抬高利率，挤出私人投资。
Above the revenue-maximising rate, a higher tax rate collects less.
超过收入最大的那个税率之后，更高的税率反而收得更少。
And the mix is demand-side short term, supply-side long term.
而政策组合是：短期用需求侧，长期用供给侧。