零交易成本条件下科斯定理矫正

宋圭武 原创 | 2020-04-23 11:22 | 收藏 | 投票

 零交易成本条件下科斯定理矫正

 

                     

 

    科斯认为,在交易成本为零的情况下,无论初始权利如何界定,市场自由交易都会产生最有效率的结果。具体科斯是通过一个工厂污染的例子来分析证明的,即最终通过安装过滤网,双方实现了总成本最小化和总收益最大化。这里科斯考虑的成本和收益主要是物质成本和物质收益。

    但经济学有一个最后通牒博弈案例,可以看成是一种交易费用为零的一种资源配置,但其自愿交易的结果并不符合科斯定理情况。

所谓最后通牒博弈,是指这样一个案例。两人分一笔总数固定的钱,比如100元。方法是:A提出方案,B表决。如果后者同意,则按照方案分,如果后者反对,则两人将一无所有。A在提方案时要猜测B的反应,此时自利的A的方案是留给B一点点比如一分,而自己得99.99元。如果B接受了就能得到一分钱,如果拒绝就什么也得不到。英国博弈论专家宾谟做了实验,发现提方案者倾向于50:50,而接受者倾向于,少于30%拒绝,多于30%接收。而且根据美国学者的比较文化研究,不管是在亚马逊流域的原始部落,还是在西方发达国家,上述试验结果都是成立的。

在上述案例中,在对方拒绝接受的情况下,双方的交易并没有实现总收益最大化或总成本最小化,这与科斯定理本质是矛盾的。

    如何解决这个矛盾,笔者认为,一是应扩展科斯定理中的成本和收益概念。科斯定理中的成本和收益,主要考虑的是物质成本和物质收益,并没有考虑精神成本和精神收益。而在最后通牒博弈中,当事人(不管是决定分配的还是接受分配的)实际考虑的是物质成本、物质收益和精神成本、精神收益的总和,是按照物质成本加精神成本总和最小化和物质收益加精神收益总和最大化来决定资源配置策略的。在这种情况下,对于提案者,一些提方案者倾向于50:50,而不是给自己更多,这里面就有一个精神收益的问题。因为能公平对待对方,可以给自己带来精神收益,让别人对我有尊敬感。反之,则让别人瞧不起自己,让自己有精神损失。对于接受者,一些人认为当分配给自己的方案少于30%时,倾向于拒绝,这里也是考虑到精神成本的问题。由于分配给自己的方案少于30%,一些人会感觉受到不公平对待,必然会有一种精神损失,若这种精神损失大于相应的物质收益,理性的选择必然是拒绝其物质收益,因为若接受,必然导致总收益为负值。

    二是要考虑到市场自由交易的最终效率与初始权利的界定情况是有关系的,并不是没有关系。在最后通牒博弈中,我们也看到,从整体角度看,在交易成本为零的情况下,权利的初始界定一定要考虑公平因素,并且分配方案越公平,会有越多人接受分配方案,最终越有利于实现整个群体物质收益和精神收益总和的最大化。推而广之,从社会角度看,我们也可以这样认为,在零交易成本的情况下,若对初始权利界定越公平,最终自愿交易才有可能导致社会资源配置的整体效率会越高。

由此,笔者认为,零交易成本条件下的科斯定理,正确的表述应是:在交易成本为零的情况下,从社会整体角度看,只有公平或满足一定程度公平的初始资源或产权配置,人们的自愿交易才有可能实现社会整体的资源最优配置(注意:这里是指有可能实现最优配置,并非必然是最优配置,因为社会整体的资源配置,还受其它许多因素制约,比如社会大众的理性水平、道德水平、信息不对称等情况,都是重要的制约因素);从个人局部决策角度看,人们是按照物质成本加精神成本的总和最小化或物质收益加精神收益的总和最大化来考虑资源配置最优的,并不仅仅是只考虑物质成本最小化或物质收益最大化。

对于上述结论,笔者认为也可以推广到交易成本不为零的情况。只是交易成本不为零,可能会增加初始权利公平界定的难度,同时,也会增加最终资源配置最优化的难度。但总体趋势还是应满足:初始权利界定越公平,越有利于最终资源配置效率的提高。

 

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翻译:

Amendment of Coase Theorem under Zero Transaction Cost

 

Song, Guiwu

 

Coase theorem states that if trade in an externality is possible and there are sufficiently low transaction costs, bargaining will lead to a Pareto efficient outcome regardless of the initial allocation of property. This is analyzed by an example of factory pollution issue, where both parties reached maximum mutual benefit through negotiation and installation agreement.

There is a case study in economics called ultimatum game which can be seen as a relocation of resource under zero transaction cost. However, its result does not follow Coase theorem.

The ultimatum game has a rule like this: one player, the proposer, is endowed with a sum of money. They are tasked with splitting it with another player, the responder. Once the proposer communicates their decision, the responder may accept it or reject it. If the responder accepts, the money is split per the proposal; if the responder rejects, both players receive nothing. The proposer should predict the reaction of the responder. For example, if proposer has $100 and proposed a split of 99% for himself and 1% for the responder. The responder would get only $1 by accepting it or nothing by rejecting it. A British game theory expert experimented that proposer tends to propose a 50:50 split and responder would most likely accept a split of more than 30% for them. Additionally, according to comparative culture studies done by American scholars, a similar result can be experimented in both developed culture and a primitive tribe of the Amazon basin.

Under ultimatum game theorem, both parties would not reach maximum collective gain or minimum transaction cost if responder reject the proposal. This outcome does not follow standard Coase Theorem.

In order to solve this contradiction, the author suggests that below two terms could be implemented in existing theorem.

Firstly, we should extend the concept of cost and benefit in Coase Theorem. Costs and benefits in Coase's theorem, mainly considering material costs and benefits without considering spiritual costs and benefits. In the ultimatum game, the actual consideration of the material is the sum of material cost, material income, spiritual cost and spiritual income. The resource allocation strategy is determined according to the material cost plus the spiritual cost and the sum of the material income and the spiritual income. In this case, for the proposers, some planners tend to split 50:50 instead of giving themselves more, and there is a spiritual benefit problem. Because proposer can treat responder fairly, and he can bring spiritual benefits to himself and let others have respect for him. On the contrary, let responder disrespect him and he will have spiritual loss. On the responders’ perspective, most responders would tend to reject when they get less than 30%. This is also factor in the spiritual gain and loss. When responders were given a proposal of less than 30%, the sum of material gain and spiritual loss would be negative and they will reject the offer.

Secondly, we should include the initial allocation of the property as a factor as to reach Pareto efficient outcome. It can be observed from ultimatum game theorem that under zero transaction cost, more people (responder) would likely to accept the offer under fairer distribution of the property. This would eventually help both parties to reach maximum material and spiritual gain as a whole. Furthermore, we could promote this theorem into the perspective of sociology which is under sufficiently low transaction cost, bargaining will lead to Pareto efficient outcome with the fair amount of initial allocation of property.

Finally, it may be concluded that the comprehensive statement of Coase theorem should be: from social’s perspective, if trade in an externality is possible, there are sufficiently low transaction costs and the initial allocation of property is fair at certain level, bargaining may lead to a Pareto efficient outcome (note: here it may lead to a Pareto efficient outcome but not guaranteed. There are many other factors affecting the outcome, like level of rationalization, moral standards, unequal distribution of information, etc.); from individual’s perspective, people consider maximum personal gain as a sum of material and spiritual gain instead of just material gain.

Above conclusion could also be implemented into scenarios where transaction cost is high. However, this may increase the complexity of initial property allocation thus the difficulty of reaching Pareto efficient outcome. After all the overall direction is that the fairer the initial allocation of the property is, the more likely the state will reach maximum collective gain.

 

Lanzhou, Gansu, China

Email: gssgw007@sina.com

个人简介
宋圭武,男,汉族,1964年生,甘肃靖远人,中共甘肃省委党校(甘肃行政学院)中国特色社会主义理论体系研究中心主任、二级教授,甘肃省人民政府决策咨询委员会委员,主要研究方向为三农问题、经济理论和中国经济改革问题。先后…
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