Long-Run Consequences of Stabilization Policies
AP Macroeconomics Topic 5 8:29 English narration · English + 中文 subtitles burned in
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A government wants to end a recession fast.
政府想尽快结束衰退。
It spends more, cuts taxes, and the central bank makes borrowing cheap.
它增加支出、减税，央行让借钱变便宜。
It works — output rises, jobs come back.
这确实有效—— 产出上升，就业回来。
But each choice sends a bill into the future: higher prices, a bigger debt, factories never built.
但每一个选择都会把一张账单寄到未来：更高的物价、 更大的债务、永远没建起来的工厂。
Today we open that bill.
今天我们就打开这张账单。
Unit Five: what stabilization policy costs in the long run.
这是第五单元：稳定政策在长期要付出的代价。
Four ideas carry it.
四个概念贯穿全篇。
The Phillips curve.
菲利普斯曲线。
Money growth and inflation.
货币增长与通货膨胀。
Deficits, debt and crowding out.
赤字、债务与挤出效应。
And what makes an economy grow.
以及究竟是什么让经济增长。
First, what does policy do in the short run?
先看政策在短期做了什么。
Expansionary policy — more spending, lower taxes, cheaper money — pushes aggregate demand right.
扩张性政策——增加支出、降低税率、让资金更便宜—— 把总需求推向右边。
Watch the equilibrium move.
看均衡点移动。
Output rises, the price level rises, unemployment falls.
产出上升，价格水平上升，失业率下降。
That is the short run.
这就是短期。
The two tools also work together.
两种工具也可以一起用。
Fiscal policy changes government spending and taxes.
财政政策改变政府支出和税收。
Monetary policy changes the money supply, which moves the interest rate, then investment, then aggregate demand — the chain on the card.
货币政策改变货币供给， 从而影响利率，再影响投资，再影响总需求——就是卡片上的传导链。
Stabilization policy has two goals: full employment and stable prices.
稳定政策有两个目标：充分就业和物价稳定。
Point both tools the same way and a gap closes faster; point them opposite — loose fiscal with tight monetary, say — and the policy mix is mixed.
两种工具朝同一方向发力， 缺口就填得更快。
That short-run story has a second face.
短期的故事还有另一面。
Put unemployment along the bottom and inflation up the side: the short-run Phillips curve, S R P C.
把失业率放在横轴，把通货膨胀率放在纵轴， 就得到短期菲利普斯曲线。
It slopes downward.
它向下倾斜。
Stimulate demand and unemployment falls, but inflation rises.
刺激需求，失业率下降，但通胀上升。
Squeeze demand and inflation falls, but unemployment rises.
压缩需求，通胀下降，但失业率上升。
Now add the long run — the orange line.
现在加上长期——那条橙线。
The long-run Phillips curve, L R P C, is vertical, standing at the natural rate of unemployment.
长期菲利普斯曲线是垂直的，立在自然失业率上。
Vertical means no trade-off: whatever the inflation rate, the economy returns to the natural rate.
垂直意味着没有取舍：无论通胀率多少，经济都会回到自然失业率。
Policy chooses the inflation rate, not the unemployment rate.
政策选择的是通胀率，不是失业率。
Where the curves cross is long-run equilibrium: left of it an inflationary gap, right of it a recessionary gap.
两条曲线相交处就是长期均衡： 左边是通胀缺口，右边是衰退缺口。
So what moves the short-run curve?
那么什么让短期曲线移动？
Two things.
两件事。
Higher expected inflation lifts it upward.
更高的预期通胀把它向上抬。
A negative supply shock — an oil price jump, a bad harvest — pushes it right: stagflation, inflation and unemployment worsening together.
一次负向供给冲击——油价大涨、歉收——把它推向右边：滞胀， 通胀和失业同时恶化。
A demand shock moves you along the curve; a supply shock shifts the curve itself.
需求冲击让你沿曲线移动； 供给冲击让曲线本身移动。
And push unemployment below the natural rate: expectations catch up, unemployment drifts back, and only higher inflation is left.
而把失业压到自然失业率以下：预期会跟上， 失业率退回去，最后只剩更高的通胀。
In the long run, inflation is a monetary phenomenon.
在长期，通货膨胀是货币问题。
Start from the quantity theory of money, the equation of exchange: money supply times velocity equals the price level times real output.
从交换方程式开始： 货币供给乘以流通速度，等于价格水平乘以实际产出。
Velocity is how often each unit of money is spent.
流通速度是每一单位货币被花掉的次数。
In the long run velocity and real output are steady, so inflation is roughly money growth minus output growth.
在长期，流通速度和实际产出都稳定， 所以通胀大致等于货币增长减去产出增长。
On the card: money grows ten percent, output three, so prices rise about seven. That is the neutrality of money.
看卡片：货币增长百分之十， 产出增长百分之三，物价就上涨约百分之七。
Print far faster than the economy grows and you get hyperinflation.
这就是货币中性。
Your turn.
该你了。
The money supply grows eight percent a year, real output grows three percent, velocity is steady.
货币供给每年增长百分之八，实际产出增长百分之三，流通速度稳定。
Find the inflation rate.
求通货膨胀率。
Pause and try it.
先暂停，自己试一试。
Step one: write the equation of exchange in growth rates.
第一步：把交换方程式写成增长率形式。
Step two: velocity is steady, so it drops out.
第二步：流通速度稳定，所以它被约掉。
Step three: inflation is money growth minus output growth.
第三步：通胀等于货币增长减去产出增长。
Put the numbers in — eight percent minus three.
代入数字——百分之八减百分之三。
The answer is five percent a year.
答案是每年百分之五。
That money bought no extra goods; it went straight into prices.
这些钱没买到任何多余的商品，所以它直接变成了价格。
Now the second long-run cost.
现在看第二个长期代价。
When a government spends more in a year than it collects in tax, that gap is a budget deficit — a flow, one year's shortfall.
当政府一年的支出超过它收到的税， 这个缺口就是预算赤字——它是流量，是一年的差额。
Collect more than you spend and it is a budget surplus instead.
国家债务是存量： 过去所有赤字堆起来的那一堆。
The national debt is a stock: the pile every past deficit has built. So a country can cut its deficit and still watch its debt grow — and pay interest on the pile every year.
所以一个国家可以削减赤字，却仍看着债务长大—— 而且每年都要为那一堆付利息。
How does a government actually borrow?
政府究竟怎么借钱？
It sells bonds in the market for loanable funds.
它在可贷资金市场上卖债券。
Saving supplies the funds; firms and the government demand them; where the two lines cross sets the real interest rate.
储蓄提供资金； 企业和政府需要资金；两条线相交的地方决定实际利率。
Now watch: the government borrows heavily, demand shifts right, and the real rate is bid up.
现在看好。 政府大量借款，需求向右移动，实际利率被抬高。
Here is that graph the way the exam wants it: the real interest rate up the side, the quantity of loanable funds along the bottom.
这就是考试要你画的那张图：纵轴是实际利率，横轴是可贷资金的数量。
Government borrowing pushes the demand line right, and the rate climbs.
政府借款把需求线推向右边，利率随之上升。
A higher rate makes borrowing dearer, so some machines and factories are never bought.
利率更高使借钱更贵，于是有些机器、有些工厂永远不会被买下来。
That is crowding out.
这就是挤出效应。
And less investment this year means a smaller capital stock next year — slower growth for a long time.
而今年投资更少，意味着明年资本存量更小——增长会长期变慢。
Let's put numbers on it.
我们来加上数字。
A government borrows five hundred billion dollars to pay for a deficit.
政府借了五千亿美元来弥补赤字。
On the loanable funds graph, that borrowing makes demand shift right.
在可贷资金图上， 这笔借款使需求向右移动。
The real interest rate then rises from three percent to four percent.
实际利率于是从百分之三上升到百分之四。
At that higher rate, firms cut investment by one hundred and fifty billion.
在更高的利率下，企业把投资削减了一千五百亿。
So aggregate demand rises by three hundred and fifty billion, not five hundred.
所以总需求只增加三千五百亿， 而不是五千亿。
And the investment that never happened is the real long-run cost: a smaller capital stock, and slower growth for years to come.
而那些没有发生的投资， 才是真正的长期代价：更小的资本存量，以及未来多年更慢的增长。
Which brings us to growth itself.
这把我们带到增长本身。
Economic growth is a sustained rise in real G D P per capita — output per head, not total output.
经济增长是人均实际国内生产总值的持续上升—— 是人均产出，不只是总产出。
That is what lifts living standards.
这才是提高生活水平的东西。
It comes from more and better resources and from higher productivity — more output from each input. Its drivers are physical capital — more tools and machines per worker — human capital, and technology.
它来自两个方面： 更多更好的资源——劳动力、机器、教育——以及更高的生产率， 每一份投入带来更多产出。
On a diagram, growth is the production possibilities curve moving outward and a rightward shift of L R A S.
在图上，增长就是生产可能性曲线向外移动、 长期总供给向右移动。
Here it is.
看这里。
The blue curve is everything the economy can produce today.
蓝色曲线是今天这个经济体所能生产的一切。
Growth pushes it outward to the green curve, because there are more or better resources.
增长把它向外推到绿色曲线， 因为资源更多或更好了。
A war or a disaster pulls it inward — the dashed orange curve.
战争或灾难则相反，把它向内拉——那条橙色虚线。
And notice what growth is not: moving from inside the curve out onto it is just putting idle workers back to work.
还要注意什么不算增长：从曲线内部移到曲线上， 只是让闲置的工人重新工作。
Growth is the curve itself moving.
增长是曲线本身在移动。
So what can a government do?
那么政府能做什么？
Three families of policy.
三大类政策。
Investment in infrastructure and education: roads, ports and power, plus schools and health care, which build human capital.
建设资本：道路、港口和电力， 再加上学校和医疗，它们建设的是人力资本。
Push technology: research and development, patents, universities.
推动技术：研究与开发、专利、大学。
And get institutions right: secure property rights, honest courts, sensible incentives.
以及把制度理顺：稳固的产权、公正的法院、合理的激励。
Policies aimed at incentives to work, save and invest are called supply-side fiscal policies.
那些针对工作、储蓄和投资意愿的政策，叫做供给侧财政政策。
Each shifts long-run aggregate supply right.
每一类都把长期总供给推向右边。
That is the long-run theme of this unit: policies that crowd out or discourage investment slow growth, and policies that encourage capital formation speed it up.
这就是本单元的长期主线：挤出或抑制投资的政策会拖慢增长， 而鼓励资本形成的政策会加快增长。
Three marks students throw away.
三个学生常丢的分。
First, the long-run Phillips curve is vertical at the natural rate — write vertical, and write no long-run trade-off.
第一，长期菲利普斯曲线在自然失业率上是垂直的—— 要写"垂直"，也要写"长期没有取舍"。
Second, decide whether you are moving along the curve or shifting it: a demand shock moves you along, a supply shock shifts the whole curve.
第二，判断你是沿着曲线移动， 还是让曲线移动：需求冲击让你沿曲线走，供给冲击让整条曲线移动。
Third, draw crowding out on the loanable funds graph, never on aggregate demand and supply.
第三， 挤出效应要画在可贷资金图上，绝不要画在总需求总供给图上。
Get those three right, and Unit Five is yours.
这三点做对，第五单元就是你的了。
Four quick checks — the answers are at the bottom, so cover them and try first.
四个快速自测——答案就在下面，先盖住它们，自己试一试。
Is the long-run Phillips curve sloped or vertical?
长期菲利普斯曲线是倾斜的还是垂直的？
Vertical, at the natural rate.
垂直的，立在自然失业率上。
Money grows eight percent, output two — what is inflation?
货币增长百分之八，产出增长百分之二——通胀大约是多少？
About six percent.
大约百分之六。
Deficit or debt: which is a yearly flow?
赤字还是债务，哪个是每年的流量？
The deficit.
赤字。
And crowding out reduces which spending?
挤出效应减少哪一类支出？
Private investment.
私人投资。