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Coase theorem

Theorem in economics

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Through Economic system, Externality and Economy

In practice, numerous complications, including imperfect information and poorly defined property rights, can prevent this optimal Coasean bargaining solution. In his 1960 paper, Coase specified the ideal conditions under which the theorem could hold and then also argued that real-world transaction costs are rarely low enough to allow for efficient bargaining. Hence, the theorem is almost always inapplicable to economic reality but is a useful tool in predicting possible economic outcomes.

The Coase theorem is considered an important basis for most modern economic analyses of government regulation, especially in the case of externalities, and it has been used by jurists and legal scholars to analyze and resolve legal disputes. George Stigler summarized the resolution of the externality problem in the absence of transaction costs in a 1966 economics textbook in terms of private and social cost, and for the first time called it a "theorem". Since the 1960s, a voluminous amount of literature on the Coase theorem and its various interpretations, proofs, and criticism has developed and continues to grow.

The theorem

Coase developed his theorem when considering the regulation of radio frequencies. Competing radio stations could use the same frequencies and would therefore interfere with each other's broadcasts. The problem faced by regulators was how to eliminate interference and allocate frequencies to radio stations efficiently. What Coase proposed in 1959 was that as long as property rights in these frequencies were well defined, it ultimately did not matter if adjacent radio stations interfered with each other by broadcasting in the same frequency band. Furthermore, it did not matter to whom the property rights were granted. His reasoning was that the station able to reap the higher economic gain from broadcasting would have an incentive to pay the other station not to interfere.

In the absence of transaction costs, both stations would strike a mutually advantageous deal. It would not matter which station had the initial right to broadcast; eventually, the right to broadcast would end up with the party that was able to put it to the most highly valued use. Of course, the parties themselves would care who was granted the rights initially because this allocation would impact their wealth, but the result of who broadcasts would not change because the parties would trade to the outcome that was overall most efficient. This counterintuitive insight—that the initial imposition of legal entitlement is irrelevant because the parties will eventually reach the same result—is Coase's invariance thesis.

Coase's main point, clarified in his article "The Problem of Social Cost", published in 1960 and cited when he was awarded the Nobel Prize in 1991, was that transaction costs, however, could not be neglected, and therefore, the initial allocation of property rights often mattered. As a result, one normative conclusion sometimes drawn from the Coase theorem is that liability should initially be assigned to the actors for whom the costs of avoiding the externality problem are the lowest. The problem in real life is that nobody knows ex ante the most valued use of a resource, and also that there exist costs involving the reallocation of resources by government. Another, more refined, normative conclusion also often discussed in law and economics is that government should create institutions that minimize transaction costs, so as to allow misallocations of resources to be corrected as cheaply as possible.

  1. In the case of zero transaction costs, no matter how the rights are initially allocated, negotiations between the parties will lead to the Pareto optimal allocation of resources;
  2. In the case of non-zero transaction costs, different rights allocation definitions will lead to different resource allocations;
  3. Because of the existence of transaction costs, different rights definitions and allocations will bring about resource allocation with different benefits. Therefore, the establishment of the property rights system is the basis for optimizing resource allocation (to Pareto optimal).

When faced with an externality, the same efficient outcome can be reached without any government intervention as long as the following assumptions hold:

  1. Property rights must be clearly defined.
  2. There must be little to no transactions costs.
  3. (Following 2.) There must be few affected parties (or else the transactions costs of organizing them gets to be too great).
  4. There must be no wealth effects. The efficient solution will be the same, regardless of who gets the initial property rights.

The Coase theorem shows that the essence of the market is not price, but property rights. As long as there are property rights, people will naturally "negotiate" a reasonable price.

While the mainstream interpretation of the Coase Theorem has long been foundational to law and economics, it is not without its significant challenges and internal contradictions. A provocative recent law review article builds on these tensions, arguing that the theorem remains profoundly misunderstood. The author contends that in "The Problem of Social Cost", Coase actually envisioned a comprehensive state-owned macroeconomic framework. In this model, the state controls all factors of production and private property is abolished, allowing the nation to be managed as a single integrated 'firm' through a strategic blend of market mechanisms, firm structures, and administrative action.

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