General Equilibrium with Free Entry: A Synthetic Approach to the Theory of Perfect Competition*
General Equilibrium with Free Entry: A Synthetic Approach to the Theory of Perfect Competition*
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自由进入的一般均衡：完美竞争理论的综合方法*
DOI：
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发表时间：
1983
影响因子：
12.6
通讯作者：
H. Sonnenschein
中科院分区：
文献类型：
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作者：
W. Novshek;H. Sonnenschein
本文的目的是解释一种新的完全竞争理论，该理论综合了阿罗-德布鲁-麦肯齐和马歇尔理论，并总结了大量研究人员的最新工作。综合理论提供了逻辑上精确的一般均衡框架，既可用于实证分析，也可构成福利经济学经典定理的基础；在这些方面都遵循ADM理论。然而，正如马歇尔理论中的那样，存在着自由进入的形式，即可以使用现有技术的无限企业池的形式。与马歇尔理论一样，每个公司可用的平均成本曲线是 U 形的。
与马歇尔理论和 ADM 理论相反，我们不将价格接受作为假设。我们使用“完全竞争”一词来描述企业相对于其所参与的市场而言规模任意小的情况。我们模型中的公司正确地认识到他们投放到市场上的数量对价格的影响，并考虑到这一点，他们采取行动以实现利润最大化。 “完全竞争均衡”被定义为当企业相对于市场变小时的均衡极限点，根据古诺，我们观察到随着企业变小，它们影响价格的能力消失。
确定了一个对于竞争市场的生存能力非常重要的新条件。笼统地说，这种条件要求价格为企业提供适当的进入信号。如果人们认为每个公司都与使用一种未定价和不可分割的资源（有时称为企业家精神）相关，那么在均衡状态下，该因素的回报必定会随着进入而下降，并随着退出而上升。不仅综合理论的稳定性定理而且存在定理都拒绝将竞争模型应用于进入增加（而退出减少）类似企业利润的制度。
The purpose of this essay is to explain a new theory of perfect competition that synthesizes the Arrow-Debreu-McKenzie and Marshallian theories and summarizes the recent work of a large number of researchers. The synthetic theory provides a logically precise general equilibrium framework that can be used both for positive analysis as well as to form a basis for the classical theorems of welfare economics; in these aspects it follows the ADM theory. However, as in the Marshallian theory, there is free-entry in the form of an unbounded pool of firms which have access to the existing technology. Also as in the Marshallian theory, the average cost curves available to each firm are U-shaped.
In contrast to both the Marshallian and the ADM theories, we do not take price taking as a hypothesis. We use the term "perfect competition" to describe a situation in which firms are arbitrarily small relative to the markets in which they are involved. The firms in our model correctly perceive the effect of the amount that they place on the market on prices and they act to maximize profit with this in mind. "Perfectly competitive equilibria" are defined as the limit points of equilibria as firms become small relative to the market, and following Cournot, we observe that as firms become small their ability to influence price disappears.
A new condition is identified which is important for the viability of competitive markets. Loosely speaking, this condition requires that prices provide the proper entry signals for firms. If one thinks of each firm as associated with the use of an unpriced and nondivisible resource, sometimes referred to as entrepreneurship, then in equilibrium the returns to that factor must fall with entry and rise with exit. Not only the stability theorems of the synthetic theory but also the existence theorem reject the application of the competitive model to a regime in which entry drives up (and exit reduces} the profit of similar firms.