Overcapacity and Undercapacity: Glutology
产能过剩与产能不足：生产过剩的学问
The third brief in our series on big economic ideas looks at Say’s law
“重大经济思想”系列之三——萨伊定律
In 1804 Jean-Baptiste Say enrolled in the National Conservatory of Arts and Crafts in Paris to learn the principles of spinning cotton. The new student was 37 years old, points out his biographer, Evert Schoorl, with a pregnant wife, four children and a successful career in politics and letters trailing behind him. To resume his studies, he had turned down two lucrative offers from France’s most powerful man, Napoleon Bonaparte. The ruler would have paid him handsomely to write in support of his policies. But rather than “deliver orations in favour of the usurper”, Say decided instead to build a cotton mill, spinning yarn not policy.
让-巴蒂斯特·萨伊（Jean-Baptiste Say）于1804年入读巴黎国立工艺学院（National Conservatory of Arts and Crafts），学习棉纺原理。传记作家埃夫特·斯古勒（Evert Schoorl）指出，这名新生37岁，带着怀孕的妻子和四个孩子，此前他在政界和文坛已颇有建树。为继续自己的学业，萨伊两次拒绝了法国最有权势的人拿破仑·波拿巴（Napoleon Bonaparte）发出的条件优厚的邀请。这位统治者愿以优渥的报酬请萨伊撰文支持自己的政策。但萨伊没有“为篡权者发声”，而是决定建一家棉纺厂，纺纱线而不是编政策。
Napoleon was right to value (and fear) Say’s pen. As a pamphleteer, editor, scholar and adviser, he was a passionate advocate for free speech, trade and markets. He had imbibed liberal principles from his heavily annotated copy of Adam Smith’s “The Wealth Of Nations” and bolstered his patriotic credentials in battle against Prussian invaders. (During breaks in the fighting, he discussed literature and political economy with other learned volunteers “almost within cannonballs’ reach”.)
拿破仑看重（且畏惧）萨伊的文笔，这是对的。作为檄文作者、编辑、学者和顾问，萨伊积极倡导自由言论、自由贸易及自由市场。他从自己那本写满评注的亚当·斯密的《国富论》中汲取自由主义思想，在对抗普鲁士侵略的战斗中强化了自己的爱国形象。（在战斗间隙，他与其他博学的志愿者讨论文学和政治经济学，而“炮弹几乎就在脚边炸开”。）
His greatest work was “A Treatise on Political Economy”, a graceful exposition (and extension) of Smith’s economic ideas. In Say’s time, as nowadays, the world economy combined strong technological progress with fitful demand, spurts of innovation with bouts of austerity. In France output of yarn grew by 125% from 1806 to 1808, when Say was starting his factory. In Britain the Luddites broke stocking frames to stop machines taking their jobs.
他最伟大的著作《政治经济学概论》（A Treatise on Political Economy）精妙阐述（并发展了）亚当·斯密的经济学理念。萨伊所在的时代跟现在一样，世界经济在技术方面有长足的进步但需求时起时落，创新迸发而经济紧缩频现。1806至1808年间，法国的纱线产量上升了125%，而萨伊的纺纱厂正是在那时起步。在英国，卢德分子捣毁织袜机以阻止机器抢走自己的工作。
On the other hand, global demand was damaged by failed ventures in South America and debilitated by the eventual downfall of Napoleon. In Britain government spending was cut by 40% after the Battle of Waterloo in 1815. Some 300,000 discharged soldiers and sailors were forced to seek alternative employment.
另一方面，因在南美扩张失利，全球需求受损，而拿破仑的最终垮台更令需求萎靡不振。1815年滑铁卢战役后，英国政府削减了40%的开支。约30万名退役士兵和水手被迫另谋出路。
The result was a tide of overcapacity, what Say’s contemporaries called a “general glut”. Britain was accused of inundating foreign markets, from Italy to Brazil, much as China is blamed for dumping products today. In 1818 a visitor to America found “not a city, nor a town, in which the quantity of goods offered for sale is not infinitely greater than the means of the buyers”. It was this “general overstock of all the markets of the universe” that came to preoccupy Say and his critics.
结果便是一轮产能过剩，在萨伊那个年代人们称之为“全面生产过剩”。英国货被指责充斥了从意大利到巴西的各个外国市场，就和今天中国被指向全球倾销商品一样。1818年，来到美国的一位访客发现“待售商品的数量总是大大超出购买者的财力，每一城镇莫不如此”。 “全球各个市场的全面过剩”成为萨伊及其批评者的关注焦点。
In trying to explain it, Say at first denied that a “general” glut could exist. Some goods can be oversupplied, he conceded. But goods in general cannot. His reasoning became known as Say’s law: “it is production which opens a demand for products”, or, in a later, snappier formulation: supply creates its own demand.
试图解释该现象时，萨伊先是否认可能存在“全面”过剩。他承认有些商品可能供应过剩。但商品不会全面过剩。他的理论如今被称为萨伊定律：“生产自行开启了对产品的需求”，或套用后期更简明的表述：供给自行创造需求。
This proposition, he admitted, has a “paradoxical complexion, which creates a prejudice against it”. To the modern era, it sounds like the foolhardy belief that “if you build it, they will come”. Rick Perry, America’s energy secretary, was ridiculed after a recent visit to a West Virginia coal plant for saying, “You put the supply out there and the demand will follow.”
他承认，这一理念“有一种矛盾的特性，令人产生偏见 ”。在现代人听来，这个定律有点像“做出了东西，就自然会有人要”这种愚勇的信念。最近美国能源部长里克·佩里（Rick Perry）在访问西弗吉尼亚一家火力发电厂时发表的言论备受嘲讽。他说，“你供应了，需求自然就来了。”
To grasp Say’s point requires two intellectual jumps. The first is to see past money, which can obscure what is really going on in an economy. The second is to jump from micro to macro, from a worm’s eye view of individual plants and specific customers to a panoramic view of the economy as a whole.
要理解萨伊的观点，需要做两次思维跳跃。第一，要超越金钱看问题，因为金钱会掩盖经济体内的实际情况。第二是从微观跳跃至宏观，从细观个别工厂和某些顾客转向俯瞰经济全景。
Firms, like coal plants and cotton mills, sell their products for money. But in order to obtain that money, their customers must themselves have previously sold something of value. Thus, before they can become a source of demand, customers must themselves have been a source of supply. What most people sell is their labour, one of several “productive services” on offer to entrepreneurs. By marshalling these productive forces, entrepreneurs can create a new item of value, for which other equally valuable items can then be exchanged. It is in this sense that production creates a market for other products. In the course of making his merchandise, a producer will pay wages to his workers, rent to his landlord, interest to his creditors, the bills of his suppliers and any residual profits to himself. These payments will at least equal the amount the entrepreneur can get for selling his product. The payments will therefore add as much to spendable income as the recipients’ joint enterprise has added to supply.
就像火电厂和棉纱厂那样，各类公司为赚钱而销售产品。而它们的顾客要获得购买产品的资金，就必须先卖出一些具有价值的东西。因此，在成为需求的源头之前，顾客自己必须先成为供应的源头。大多数人出卖的是自己的劳动力——向企业家提供的几种“生产性服务”之一。通过组织这些生产力，企业家可以创造出具有价值的新产品，可用来换取相同价值的其他产品。从这个意义上讲，生产为其他产品创造了市场。在制造商品的过程中，生产者会付工资给员工，付租金给房东，付利息给债权人，支付供应商账单，支付利润给自己。这些支出金额至少会等于企业家销售产品所能获得的收入。因此，这些支出令可支配收入增加，增加的程度等同于收款人此前合力提供的供给。
That supply creates demand in this way may be easy enough to grasp. But in what sense does supply create its “own” demand? The epigram seems to suggest that a coal plant could buy its own coal – like a subsistence farmer eating the food he grows. In fact, of course, most producers sell to, and buy from, someone else. But what is true at the micro level is not true at the macro level. At the macro level, there is no someone else. The economy is an integrated whole. What it purchases and distributes among its members are the self-same goods and services those members have jointly produced. At this level of aggregation, the economy is in fact not that different from the subsistence farmer. What it produces, what it earns, and what it buys is all the same, a “harvest” of goods and services, better known as gross domestic product.
供给以此方式创造了需求，这也许不难明白。但从什么意义上能说供给创造了“自己”的需求？这一妙语似乎在说，煤矿可以买回自己产的煤炭，就像自给自足的农民吃自己种的粮食那样。但实际上，不消说，大多数生产商都是从别处购入材料，产品也都是卖给别人的。然而，那是微观层面的情况，在宏观层面并非如此。宏观层面上不存在“别人”。经济是统一的整体。经济体在成员中购入和分配的正是这些成员合力生产的同样那些商品和服务。如此聚合来看，经济体与自给自足的农民差别不大。其生产的、赚取的、购入的，根本是一回事，就是商品和服务的“收成”——更为人熟知的说法是“国内生产总值”。
From head to foot
从头到脚
How then did Say explain the woes of his age, the stuffed warehouses, clogged ports and choked markets? He understood that an economy might oversupply some commodities, if not all. That could cause severe, if temporary, distress to anyone involved in the hypertrophied industries. But he argued that for every good that is too abundant, there must be another that is too scarce. The labour, capital and other resources devoted to oversupplying one market must have been denied to another more valuable channel of industry, leaving it under-resourced.
那么萨伊如何解释他那个时代的困境——仓库积压、港口拥堵、市场窒息？他明白，一个经济体内纵然不会全部商品都供过于求，但仍可能出现部分商品过剩。在过度扩张的产业内，这可能对每个人都造成严重（尽管是暂时的）困扰。但他认为，有一种商品过剩，就必然会有一种商品稀缺。投入一个过剩市场的劳动力、资本及其他资源必然是另一更具价值的产业部门所缺的，造成其资源不足。
Subsequent economists have tried to make sense of Say’s law in the following way. Imagine an economy that consists only of shoes and hats. The cobblers intend to sell $100-worth of shoes in order to buy the equivalent amount of hats. The hatters intend to sell wares worth $80 so as to spend the same sum at the cobbler’s. Each plan is internally consistent (planned spending matches revenue). Added together, they imply $180 of sales and an equal amount of purchases.
后来的经济学家们试图通过以下方式来理解萨伊定律。想象一个仅有鞋子和帽子这两种商品的经济体。鞋匠们打算卖出总值100美元的鞋子，以购买金额相当的帽子。帽匠们想卖出总值80美元的帽子，然后在鞋匠那里花费相同金额购买鞋子。两者的计划都具有内在一致性（计划的支出与收入相等）。加起来，这意味着180美元的销售额和同样金额的采购额。
Sadly, the two plans are mutually inconsistent. In the shoe market the producers plan to sell more than the consumers will buy. In the hat market the opposite is the case. A journalist, attentive to the woes of the shoe industry, might bemoan the economy’s egregious overcapacity and look askance at its $180 GDP target. Cobblers, he would conclude, must grasp the nettle and cut production to $80.
可惜的是，这两个计划是相互矛盾的。在鞋子市场，生产者的计划销售额大于顾客意欲购买的总额。在帽子市场，情况则相反。一位关注鞋业困境的记者可能会叹息经济存在产能严重过剩的问题，并对180美元的GDP目标表示怀疑。他会得出结论，认为鞋匠们必须忍痛减产至80美元。
The journalist might not notice that the hat market is also out of whack, in an equal and opposite way. Hat-buyers plan to purchase $100 from producers who plan to sell only $80. Unfortunately, this excess demand for hats cannot easily express itself. If cobblers can only sell $80 of shoes, they will only be able to buy the equivalent amount of hats. No one will see how many hats they would have bought had their more ambitious sales plans been fulfilled. The economy will settle at a GDP of $160, $20 below its potential.
这位记者可能没有注意到，帽子市场同样存在失衡，只是情况相反而已。帽子的买家计划购入100美元的帽子，而帽子生产者只打算卖出80美元的产品。不幸的是，对于帽子的超额需求无法轻易显现出来。假如鞋匠们只能卖出总值80美元的鞋子，他们就只能购买相等金额的帽子。没有人知道，假如鞋匠当时雄心勃勃的销售计划得以实现，他们最终会买入多少帽子。这个经济体的GDP将只能达到160美元，比实际潜力低20美元。
Say believed a happier outcome was possible. In a free market, he thought, shoe prices would quickly fall and hat prices rise. This would encourage shoe consumption and hat production, even as it discouraged the consumption of hats and production of shoes. As a result, both cobblers and hatters might sell $90 of their good, allowing the economy to reach its $180 potential. In short: what the economy required was a change in the mix of GDP, not a reduction in its level. Or as one intellectual ally put it, “production is not excessive, but merely ill-assorted”.
萨伊相信能达到更皆大欢喜的结果。他认为，在自由市场上，鞋价会迅速下跌，帽子价格则会上升。这将推动鞋子的消费和帽子的生产，同时压抑帽子的消费和鞋子的生产。结果是，鞋匠和帽匠们可能会各卖出90美元的产品，使经济体实现其180美元GDP的潜力。简言之：经济体所需的是GDP构成比例上的调整，并非整体水平的下降。或如一位认同此观点的学者所说的，“生产并没有过剩，只是调配不当而已”。
Supply gives people the ability to buy the economy’s output. But what ensures their willingness to do so? According to the logic of Say and his allies, people would not bother to produce anything unless they intended to do something with the proceeds. Why suffer the inconvenience of providing $100-worth of labour, unless something of equal value was sought in return? Even if people chose to save not consume the proceeds, Say was sure this saving would translate faithfully into investment in new capital, like his own cotton factory. And that kind of investment, Say knew all too well, was a voracious source of demand for men and materials.
供给使人们能够购买经济体的产出。但怎样确保人们愿意这样做？根据萨伊及其追随者的逻辑，如果不是想要获得收益来做点什么，人们是不愿意去生产任何东西的。为什么要劳心费力提供总值100美元的劳动？自然是为追求等值回报。即便人们选择把收益存起来而不去消费，萨伊还是确信，这笔存款会完全转化为新资本投资，就像他自己那家棉纱厂。萨伊深知，这样的投资会形成对人力和资源的巨大需求。
But what if the sought-after thing was $100 itself? What if people produced goods to obtain money, not merely as a transactional device to be swiftly exchanged for other things, but as a store of value, to be held indefinitely? A widespread propensity to hoard money posed a problem for Say’s vision. It interrupted the exchange of goods for goods on which his theory relied. Unlike the purchase of newly created products, the accumulation of money provides no stimulus to production (except perhaps the mining of precious metals under a gold or silver standard). And if, as he had argued, an oversupply of some commodities is offset by an undersupply of others, then by the same logic, an undersupply of money might indeed entail an oversupply of everything else.
但如果人们追求的是那100美元本身呢？假如人们生产货物获取金钱，但这些钱不是仅作为迅速交换其他货物的交易手段，而是作为价值存储工具被无限期持有，情况又会怎样？人们普遍喜欢囤积货币，这对萨伊的观点构成了挑战。囤积货币的倾向扰乱了萨伊理论中“以物易物”的前提。不同于购入新制造的产品，积累金钱并不刺激生产（也许金本位或银本位下的贵金属开采除外）。而且，如果像他认为的那样，某些商品的供过于求会被另一些商品的供不应求抵消，那么按同样的道理，货币供应不足也许真会导致其他一切商品的供应过剩。
Say recognised this as a theoretical danger, but not a practical one. He did not believe that anyone would hold money for long. Say’s own father had been bankrupted by the collapse of assignats, paper money issued after the French Revolution. Far from hoarding this depreciating asset, people were in such a rush to spend it, that “one might have supposed it burnt the fingers it passed through.”
萨伊承认这在理论上是一种风险，但不太可能发生。他不相信有人会长期持有货币。萨伊的父亲就因法国大革命后发行的纸币“指券”的崩溃而破产。人们绝不会囤积这种贬值的资产，而是急于把它花掉，就好像“它很烫手一样”。
In principle, if people want to hold more money, a simple solution suggests itself: print more. In today’s world, unlike Say’s, central banks can create more money (or ease the terms on which it is obtainable) at their own discretion. This should allow them to accommodate the desire to hoard money, while leaving enough left over to buy whatever goods and services the economy is capable of producing. But in practice, even this solution appears to have limits, judging by the disappointing results of monetary expansions since the financial crisis of 2007-08.
原则上，如果人们要持有更多货币，显然有一个简单的解决方案：加印货币。今时今日已有别于萨伊的时代，中央银行可自行决定加印更多货币（或放宽获取货币的条件）。这应该就能照顾到人们囤积货币的需求，同时留下足够的货币让人们购买经济体能生产的商品和服务。但实际上，自2007至2008年金融危机以来推行的宽松货币政策效果令人失望，由此看来，上述解决方案似乎也有局限性。
Say it ain’t so
萨伊非议
Today, many people scoff at Say’s law even before they have fully appreciated it. That is a pity. He was wrong to say that economy-wide shortfalls of demand do not happen. But he was right to suggest that they should not happen. Contrary to popular belief, they serve no salutary economic purpose. There is instead something perverse about an economy impoverished by lack of spending. It is like a subsistence farmer leaving his field untilled and his belly unfilled, farming less than he’d like even as he eats less than he’d choose. When Say’s law fails to hold, workers lack jobs because firms lack customers, and firms lack customers because workers lack jobs.
今天，许多人甚至在对萨伊定律一知半解时就对它加以嘲笑。这很可惜。萨伊认为经济体内不存在整体的需求不足，这是错误的。但他提出这种不足不应该发生，这是对的。与普遍的认知相反，整体需求不足对于经济并不发挥什么有益的功能。假如一个经济体因为支出不足而变得贫困，这其中倒是有些反常之处。这就好比一个自给自足的农民任田地闲置，腹中饥饿；他吃的比自己能吃的少，虽然想多干点活却又只能少干点。当萨伊定律不成立时，工人就会就业不足，因为公司缺乏顾客；而公司也会缺乏顾客，因为工人就业不足。
Say himself faced both a ruinous shortage of demand for his cotton and excess demand for his treatise. The first edition sold out quickly; Napoleon blocked the publication of a second. Eventually, Say was able to adapt, remixing his activities as his own theory would prescribe. He quit his cotton mill in 1812, notes Mr Schoorl. And within weeks of Napoleon’s exile in 1814, he printed a second edition of his treatise (there would be six in all). In 1820 he began work once again at the Conservatory in Paris—not this time as a student of spinning, but as France’s first professor of economics, instructing students in the production, distribution and consumption of wealth. He considered it a “new and beautiful science”. And, in his hands, it was.
萨伊自己生产的棉纱严重需求不足，但他撰写的专著却供不应求。第一版推出后迅速售罄；拿破仑禁止出版第二版。最终，萨伊做出了调整，照自己的理论指示的那样，重新安排了自己的活动分配。斯古勒提到，萨伊在1812年关掉了棉纱厂。1814年拿破仑被流放后的数周内，萨伊出版了自己专著的第二版（共出了六版）。1820年，他再次进入巴黎国立工艺学院——这次不是学纺纱的学生，而是成了法国首位经济学教授，给学生传授有关财富生产、分配及消费的知识。他视经济学为一门“美妙的新科学”。在他手中，确实如此。
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