柠檬市场质量的不确定性和市场机制中英对照

T h e M a r k e t s f o r“L e m o n s”: 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

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

- q)

q”。这

-not prob

出汽车，因为如果卖出汽车他不仅无法得到汽车的真实价值，也无法获得一辆新车的期望价值）

Gresham's law has made a modified reappearance. For most cars traded will be the "lemons," and good cars may not be traded at all. The "bad" cars tend to drive out the good (in much the same way that bad money drives out the good).（这里出现了一个修正后的格莱欣定律。当“柠檬”充斥汽车市场时，高质量车根本不会成交，于是，如同劣币驱逐良币一样，低质量车将高质量车逐出市场）But the analogy with Gresham's law is not quite complete: bad cars drive out the good because they sell at the same price as good cars; similarly, bad money drives out good because the exchange rate is even.（然而，该结果与格莱欣定律并不完全一样：低质量车驱逐高质量车是因为低质量车和高质量车在相同的价格水平上出售。相似地，劣

币驱逐良币是因为两者的交换利率相同）But the bad cars sell at the same price as good cars since it is impossible for a buyer to tell the difference between a good and a bad car; only the seller knows. In Gresham's law, however, presumably both buyer and seller can tell the difference between good and bad money. So the analogy is instructive, but not complete.（但是低质量车之

所以与高质量以同一个价格出售是因为买主无法区分一辆车到底是低质量的还是高质量的，这只有卖主才知道的信息。在格莱欣定律中，买主和卖主大概否可以区分劣币和良币。所

以说，这个类比具有启发性，但非完全相同）

（二）非对称信息

It has been seen that the good cars may be driven out of the market by the lemons. But

in a more continuous case with different grades of goods, even worse pathologies can exist.

Where M is the consumption of goods other than automobiles, x i is the quality of the i th automobile, and n is the number of automobiles.（其中，M代表交易者1对二手车之外其他商品的消费，x i表示第i辆汽车的质量，n为汽车的数量）

Similarly, let（同理，交易者2的效用函数是）

U2=M+∑3 2 x i

n

i=1

Three comments should be made about these utility functions:（对于这些效用函数有三点需要说明）(1) without linear utility (say with logarithmic utility) one gets needlessly mired in