So I've been working on the history of income

我一直在研究有關

and wealth distribution for the past 15 years,

所得和財富分配的歷史，已經 15 年了，

and one of the interesting lessons

從這些過往的證據裡

coming from this historical evidence

可以發現一個很有意思的道理，

is indeed that, in the long run,

那就是長期來說

there is a tendency for the rate of return of capital

資本報酬率有高於 經濟成長率的趨勢，

to exceed the economy's growth rate,

這種趨勢容易造成財富高度集中，

and this tends to lead to high concentration of wealth.

雖然並不是無止境的財富集中，

Not infinite concentration of wealth,

但是資本報酬率 (r) 與經濟成長率 (g) 差距越大，

but the higher the gap between r and g,

財富不均的程度就會越嚴重，

the higher the level of inequality of wealth

社會裡的不平等也會越嚴重。

towards which society tends to converge.

這就是我今天要談的主要因素，

So this is a key force that I'm going to talk about today,

不過讓我先說明，

but let me say right away

這並不是所得和財富分配變動的

that this is not the only important force

唯一重要因素，

in the dynamics of income and wealth distribution,

還有許多其他因素

and there are many other forces that play

在所得和財富分配的長期變動上

an important role in the long-run dynamics

扮演著重要的角色。

of income and wealth distribution.

而且還有許多資料有待蒐集。

Also there is a lot of data

今天我們比以前懂多一些，

that still needs to be collected.

不過懂的還是太少了，

We know a little bit more today

而且一定還有許多不同的演變過程，

than we used to know, but we still know too little,

像是經濟、社會、政治，

and certainly there are many different processes —

需要再多做研究。

economic, social, political —

而我今天會鎖定在這個單一因素，

that need to be studied more.

但這並不是說就沒有 其他重要因素了。

And so I'm going to focus today on this simple force,

我接下來要呈現的資料

but that doesn't mean that other important forces

大部分來自可上網取得的資料庫：

do not exist.

「全球高所得資料庫」。

So most of the data I'm going to present

這是現存最大的

comes from this database

所得不均歷史資料庫，

that's available online:

得力於數十個國家

the World Top Incomes Database.

超過三十位學者的貢獻。

So this is the largest existing

就讓我來帶大家看一些

historical database on inequality,

從資料庫裡得出的事實，

and this comes from the effort

然後我們再回來談 r 大於 g。

of over 30 scholars from several dozen countries.

事實一，

So let me show you a couple of facts

美國和歐洲所得不均的排行

coming from this database,

在上個世紀發生了大逆轉。

and then we'll return to r bigger than g.

時間拉回到 1900 年、1910 年，

So fact number one is that there has been

歐洲所得不均的排名確實高於美國，

a big reversal in the ordering of income inequality

而今天美國排名卻遠高於歐洲。

between the United States and Europe

我先聲明，

over the past century.

這裡主要的原因並不是 r 大於 g，

So back in 1900, 1910, income inequality was actually

而是與以往不同的人才供需、

much higher in Europe than in the United States,

教育跟科技間的競賽、

whereas today, it is a lot higher in the United States.

全球化有關，

So let me be very clear:

也許和美國不平等的 技能學習管道大有關係。

The main explanation for this is not r bigger than g.

美國有非常好、頂尖的大學，

It has more to do with changing supply and demand

但基礎教育卻沒有很好。

for skill, the race between education and technology,

因此不平等的技能學習管道

globalization, probably more unequal access

再加上美國高階主管的薪資福利

to skills in the U.S.,

史無前例的大幅提升，

where you have very good, very top universities

很難以教育為基礎來解釋這個問題。

but where the bottom part of the educational system

因此這之中還有許多因素，

is not as good,

但我今天不打算在這上面講太多，

so very unequal access to skills,

因為我要聚焦在財富不均。

and also an unprecedented rise

請看這項

of top managerial compensation of the United States,

關於所得不均的簡易指標。

which is difficult to account for just on the basis of education.

這是所得前 10% 者的所得

So there is more going on here,

佔總所得的比重，

but I'm not going to talk too much about this today,

所以你可以看到在一個世紀以前，

because I want to focus on wealth inequality.

歐洲的比例是在 45% 至 50% 之間，

So let me just show you a very simple indicator

美國稍微高過 40%，

about the income inequality part.

所以歐洲的所得較不平均。

So this is the share of total income

到了二十世紀上半葉，

going to the top 10 percent.

比重大大下滑，

So you can see that one century ago,

接著近數十年來，

it was between 45 and 50 percent in Europe

你可以發現美國所得不均的現象 變得比歐洲更嚴重，

and a little bit above 40 percent in the U.S.,

這正是我剛說的第一個事實。

so there was more inequality in Europe.

第二項事實跟財富不均更有關係，

Then there was a sharp decline

核心的事實就是

during the first half of the 20th century,

財富不均一直遠高於所得不均。

and in the recent decade, you can see that

雖然近幾十年來財富不均日益嚴重，

the U.S. has become more unequal than Europe,

但是比起上一個世紀，

and this is the first fact I just talked about.

現在已經沒那麼極端了。

Now, the second fact is more about wealth inequality,

然而現在與所得有關的財富總量

and here the central fact is that wealth inequality

已從一次世界大戰、大蕭條、

is always a lot higher than income inequality,

第二次世界大戰的重創中

and also that wealth inequality,

恢復正常了。

although it has also increased in recent decades,

請各位看這兩張圖表，

is still less extreme today

解釋了事實二和事實三。

than what it was a century ago,

首先，如果你注意看財富不均的程度，

although the total quantity of wealth

這是財富前 10% 者持有財富

relative to income has now recovered

佔總財富的比重，

from the very large shocks

你可以發現

caused by World War I, the Great Depression,

美國與歐洲之間有相同的逆轉，

World War II.

就跟過去所得不均的逆轉一樣。

So let me show you two graphs

所以百年前歐洲財富集中的情形

illustrating fact number two and fact number three.

高過於美國，

So first, if you look at the level of wealth inequality,

現在就顛倒過來了。

this is the share of total wealth

另外你也可以看出兩件事情，

going to the top 10 percent of wealth holders,

第一、財富不均的程度

so you can see the same kind of reversal

普遍高於所得不均。

between the U.S. and Europe that we had before

記得所得不均的情況，

for income inequality.

前 10% 者擁有的所得

So wealth concentration was higher

是總所得的 30% 至 50%，

in Europe than in the U.S. a century ago,

然而他們擁有的財富比例

and now it is the opposite.

卻一直在 60% 至 90% 之間。

But you can also show two things:

這就是事實一，

First, the general level of wealth inequality

對之後要說的很重要。

is always higher than income inequality.

財富一直都

So remember, for income inequality,

遠比所得更為集中。

the share going to the top 10 percent

事實二、

was between 30 and 50 percent of total income,

近幾十年來財富不均惡化的情況

whereas for wealth, the share is always

還不致於像 1910 年那樣嚴重。

between 60 and 90 percent.

與過去不同的是，

Okay, so that's fact number one,

現在的貧富差距依然很大，

and that's very important for what follows.

前10% 的富人擁有 60% 至 70% 的總財富，

Wealth concentration is always

但好消息是

a lot higher than income concentration.

情況的確已經比上個世紀好多了，

Fact number two is that the rise

當時 90% 的總財富 落入了前 10% 富人的口袋裡。

in wealth inequality in recent decades

那麼今天你們看到的是

is still not enough to get us back to 1910.

我稱為中間 40% 的人，

So the big difference today,

不是前 10 %，

wealth inequality is still very large,

也不是墊底的 50%，

with 60, 70 percent of total wealth for the top 10,

他們可以說是財富的中產階級，

but the good news is that it's actually

擁有總財富、國家財富的 20% 至 30%；

better than one century ago,

然而上個世紀他們卻是窮人，

where you had 90 percent in Europe going to the top 10.

因為那時候基本上沒有 財富的中產階級。

So today what you have

所以這是很重大的改變，

is what I call the middle 40 percent,

而且看到財富不均沒有完全恢復到

the people who are not in the top 10

第一次世界大戰之前的程度也很有趣，

and who are not in the bottom 50,

即便財富總量已經是恢復了。

and what you can view as the wealth middle class

沒問題吧？

that owns 20 to 30 percent

這是相較於所得的財富總值，

of total wealth, national wealth,

你可以看到特別是歐洲，

whereas they used to be poor, a century ago,

我們幾乎是回到了 第一次世界大戰之前的程度。

when there was basically no wealth middle class.

這件事其實有兩個不一樣的面向，

So this is an important change,

一個是關於我們累積的財富總量，

and it's interesting to see that wealth inequality

當然累積一大堆財富

has not fully recovered to pre-World War I levels,

這件事本身沒有不好，

although the total quantity of wealth has recovered.

特別是假如財富更分散，

Okay? So this is the total value

又比較不那麼集中的時候。

of wealth relative to income,

那麼我們真正關心的是什麼？

and you can see that in particular in Europe,

是財富不均的長期演變，

we are almost back to the pre-World War I level.

還有未來會發生什麼事。

So there are really two

我們要如何解釋 第一次世界大戰以前，

different parts of the story here.

財富差距如此大，

One has to do with

而且是大到前所未有的程度，

the total quantity of wealth that we accumulate,

那麼我們該如何看待未來呢？

and there is nothing bad per se, of course,

那麼讓我來做一些說明，

in accumulating a lot of wealth,

以及預測未來。

and in particular if it is more diffuse

我先聲明，

and less concentrated.

解釋財富為什麼比所得

So what we really want to focus on

還要更集中的最佳經濟模型

is the long-run evolution of wealth inequality,

大概是一種動態、世代的經濟模型，

and what's going to happen in the future.

其中每個人都長期

How can we account for the fact that

為了各種理由來累積財富。

until World War I, wealth inequality was so high

假使人們累積財富

and, if anything, was rising to even higher levels,

只是為了因應生命週期，

and how can we think about the future?

為了在他們老的時候

So let me come to some of the explanations

還有能力花錢消費，

and speculations about the future.

那麼財富不均的情形

Let me first say that

應該和所得不均的情形

probably the best model to explain

相差不遠。

why wealth is so much

可是你很難說明

more concentrated than income

為什麼財富不均要比所得不均更嚴重，

is a dynamic, dynastic model

只憑生命週期理論，

where individuals have a long horizon

所以你需要一個情境，

and accumulate wealth for all sorts of reasons.

在其中的人們會為了 其他理由累積財富。

If people were accumulating wealth

一般來說，他們想把財富

only for life cycle reasons,

交給下一代、他們的小孩，

you know, to be able to consume

或者有時候他們累積財富

when they are old,

是為了特權──伴隨財富而來的權力。

then the level of wealth inequality

所以累積財富一定有除了

should be more or less in line

生命週期以外的理由，

with the level of income inequality.

來解釋我們在資料裡發現的情況。

But it will be very difficult to explain

在這種累積財富

why you have so much more wealth inequality

是為了累積世代財富的變動模式之中，

than income inequality

會有各種毫無規則且加倍的衝擊。

with a pure life cycle model,

舉例來說：

so you need a story

有些家庭有非常多的小孩，

where people also care

因此財富就會分散，

about wealth accumulation for other reasons.

有些家庭的小孩則較少。

So typically, they want to transmit

你也會對資產報酬率感到吃驚，

wealth to the next generation, to their children,

有的家庭有大筆資本利得，

or sometimes they want to accumulate wealth

有的卻投資失利。

because of the prestige, the power that goes with wealth.

因此財富累積的過程

So there must be other reasons

總是會有一些流動，

for accumulating wealth than just life cycle

有些人會往上升、 有些人則會往下掉。

to explain what we see in the data.

重點是任何在這種模型下，

Now, in a large class of dynamic models

有這種特定的變動衝擊，

of wealth accumulation

財富不均的水平

with such dynastic motive for accumulating wealth,

會成為急遽升高的 r 減 g 函數。

you will have all sorts of random,

財富報酬率與經濟成長率之間的差異

multiplicative shocks.

為什麼重要，

So for instance, some families

想當然是因為只要 r 減 g 的數值越大，

have a very large number of children,

最初財富不均的情況就會被擴大得更快。

so the wealth will be divided.

舉個簡單的例子：

Some families have fewer children.

假設 r 是 5% 而 g 是 1%，

You also have shocks to rates of return.

財富持有人只需要再投資

Some families make huge capital gains.

資本所得的五分之一，

Some made bad investments.

他們財富增加的速度

So you will always have some mobility

就會跟經濟成長一樣快。

in the wealth process.

因此創造和保有大筆財富就更容易，

Some people will move up, some people will move down.

因為你可以消費五分之四，

The important point is that,

假設零稅率，

in any such model,

你就可以再投資五分之一。

for a given variance of such shocks,

當然有些家庭會消費多一些、

the equilibrium level of wealth inequality

有的則消費較少，

will be a steeply rising function of r minus g.

分配上就會有一些變動，

And intuitively, the reason why the difference

但是總的來看， 他們只要再投資五分之一，

between the rate of return to wealth

這樣就能維持財富高度不均。

and the growth rate is important

現在你應該不會驚訝於

is that initial wealth inequalities

r 永遠可以大於 g 這句話了，

will be amplified at a faster pace

因為事實上，

with a bigger r minus g.

這種情況在人類史上很常見。

So take a simple example,

這種情況大家都能看得一清二楚，

with r equals five percent and g equals one percent,

理由很簡單，

wealth holders only need to reinvest

因為史上大多數時候 經濟成長率幾乎是 0%。

one fifth of their capital income to ensure

經濟成長率也許是 0.1%、0.2% 或 0.3%，

that their wealth rises as fast

但人口和人均產出的成長率非常慢，

as the size of the economy.

那時候資本報酬率

So this makes it easier

當然不會是 0%。

to build and perpetuate large fortunes

以土地來說，

because you can consume four fifths,

在工業化以前的社會，

assuming zero tax,

土地是典型的資產，

and you can just reinvest one fifth.

報酬率通常是 5%。

So of course some families will consume more than that,

任何讀過珍奧斯汀作品的人都知道。

some will consume less, so there will be

假如你想要得到一千英磅的年所得，

some mobility in the distribution,

你應該要有價值兩萬英鎊的資本，

but on average, they only need to reinvest one fifth,

兩萬的 5% 就是一千。

so this allows high wealth inequalities to be sustained.

這就是以前社會的基礎，

Now, you should not be surprised

因為 r 大於 g

by the statement that r can be bigger than g forever,

就會讓財富以及資產的持有者可以

because, in fact, this is what happened

靠著資本所得過生活，

during most of the history of mankind.

還能在生活中做些別的事，

And this was in a way very obvious to everybody

而不是只關心能不能填飽肚子。

for a simple reason, which is that growth

我的歷史研究

was close to zero percent

有一個重要的結論是

during most of the history of mankind.

現代工業的發展並未如我們期待

Growth was maybe 0.1, 0.2, 0.3 percent,

改變這個簡單的事實太多。

but very slow growth of population

當然經濟成長率

and output per capita,

隨著工業革命後增加，

whereas the rate of return on capital

通常是多出零到 1% 或 2%，

of course was not zero percent.

不過同一時間

It was, for land assets, which was

資本報酬率也增加了，

the traditional form

所以貧富差距沒多少改變。

of assets in preindustrial societies,

二十世紀

it was typically five percent.

是由許多事件交織成的特殊時代。

Any reader of Jane Austen would know that.

首先是非常低的報酬率，

If you want an annual income of 1,000 pounds,

肇因於 1914 年和 1945 年 戰爭造成的衝擊、

you should have a capital value

財富破壞、通貨膨脹、

of 20,000 pounds so that

以及大蕭條期間的破產，

five percent of 20,000 is 1,000.

以上原因讓個人的財富報酬率

And in a way, this was

在 1914 到 1945 年時

the very foundation of society,

下降到異常低的程度。

because r bigger than g

接著在戰後期間

was what allowed holders of wealth and assets