柠檬市场：质量的不确定性和市场机制(中英对照)

The Markets for “Lemons”:

Quality uncertainty and The Market Mechanism

柠檬市场：质量的不确定性和市场机制

Geogre A. Akerlof 阿克洛夫

一、引言

This paper relates quality and uncertainty. The existence of goods of many grades poses interesting and important problems for the theory of markets.（本文论述的是质量和不确定性问题。现实中存在大量多种档次的物品给市场理论提出了饶有趣味而十分重大的难题）On the one hand, the interaction of quality differences and uncertainty may explain important institutions of the labor market.（一方面，质量差异和不确定性的相互作用可以解释劳动力的重要机制）On the other hand, this paper presents a struggling attempt to give structure to the statement: "Business in under-developed countries is difficult"; in particular, a structure is given for determining the economic costs of dishonesty.（另一方面，本文试图通过讨论获得这样的结论：在不发达国家，商业交易是困难的，其中，特别论及了欺骗性交易的经济成本）Additional applications of the theory include comments on the structure of money markets, on the notion of "insurability," on the liquidity of durables, and on brand-name goods.（本文的理论还可以用来研究货币市场、保险可行性、耐用品的流动性和名牌商品等问题）

There are many markets in which buyers use some market statistic to judge the quality of prospective purchases.（在许多市场中，买者利用市场的统计数据来判断他们将要购买的商品的质量）In this case there is incentive for sellers to market poor quality merchandise, since the returns for good quality accrue mainly to the entire group whose statistic is affected rather than to the individual seller. As a result there tends to be a reduction in the average quality of goods and also in the size of the market.（在这种情况下，卖者有动力提供低质量商品，因为某种商品的价格主要取决于所有同类商品质量的统计数据而非该商品的实际质量。结果，商品的平均质量将趋于下降，市场规模将不断缩小）It should also be perceived that in these markets social and private returns differ, and therefore, in some cases, governmental intervention may increase the welfare of all parties. Or private institutions may arise to take advantage of the potential increases in welfare which can accrue to all parties.（我们还可以观察到在这种市场上，对个人和社会有不同的回报，因此，某种情况下，政府的干预可以增进社会的总体福利水平。或者说，私人组织利用了整个社会福利水平潜在的增长机会而使自己获利）By nature, however, these institutions are nonatomistic, and therefore concentrations of power- with ill consequences of their own-can develop.（实际上，这些私人组织的行动所产生的影响并非可以忽略不计，因此，尽管集权本身有许多负面影响，但是，一定

程度上的集权可以保证经济的健康发展）

The automobile market is used as a finger exercise to illustrate and develop these thoughts. It should be emphasized that this market is chosen for its concreteness and ease in understanding rather than for its importance or realism.（下面，我们用汽车市场作为例子来阐释和进一步发展以上的思想。需要指出的是，之所以选择旧车市场来讨论，是因为这个例子很具体，并且容易理解，而不是因为它的重要性和有何现实意义）

二、以汽车市场模型为例

（一）汽车市场

The example of used cars captures the essence of the problem. From time to time one hears either mention of or surprise at the large price difference between new cars and those which have just left the showroom. The usual lunch table justification for this phenomenon is the pure joy of owning a "new" car.（旧车市场的例子可以抓住问题的本质。人们不止一次的听说或惊讶于新车与刚刚开出样品陈列室的汽车之间的价格存在巨大差别。对于这种情况最普遍的解释是人们有一种对“新”车的特别偏好）We offer a different explanation. Suppose (for the sake of clarity rather than reality) that there are just four kinds of cars. There are new cars and used cars. There are good cars and bad cars (which in America are known as "lemons"). A new car may be a good car or a lemon, and of course the same is true of used cars.（假设（作出这种假设只是为了简化分析，而非从实际出发）用四种汽车：新车和旧车；高质量的车和低质量的车（低质量的车在美国被称为“柠檬”）。一辆新车可能是高质量的，也可能是“柠檬”，当然一辆旧车也同样有两种情况）

The individuals in this market buy a new automobile without knowing whether the car they buy will be good or a lemon. But they do know that with probability q it is a good car and with probability (1-q) it is a lemon; by assumption, q is the proportion of good cars produced and (1 - q) is the proportion of lemons.（在这样的市场上，消费者买新车时并不知道车辆到底是高质量的还是“柠檬”，但是他知道这辆车是高质量的概率是q，是“柠檬”的概率是“1-q”。这里假设q是高质量车占所有汽车的比率，1-q是“柠檬”的比率）

After owning a specific car, however, for a length of time, the car owner can form a good idea of the quality of this machine; i.e., the owner assigns a new probability to the event that his car is a lemon. This estimate is more accurate than the original estimate.（车主在拥有汽车后一段时间内就会了解到该车的质量，也就是说，此时车主可以赋予该车可能是“柠檬”的一个概率值，这个估计比初始的估计更加准确）An asymmetry in available information has developed: for the sellers now have more knowledge about the quality of a car than the buyers. But good cars and bad cars must still sell at the same price- since it is impossible for a buyer to tell the difference between a good car and a bad car.（于是，