Chapter 35
Externalities

About the externalities

So far, we have implicitly assumed that forms bear al the costs and benefits associated with the production process

A production externality arises when this assumption does not hold

production externality: when the choice of one firm affect the production possibilities of another firm

Externalities can be negative if the effects on the other firm are bad or positive if the effects on the other firm are good

The steel firm and fishery example

If the firms emerged, there would be no externality!

We can also apply a tax based on pollution

In merged firm, Screen Shot 2018-01-23 at 9.14.43 pm


The lefthand side is the reduction in cost to the steel form from an extra unit of x - can be interpreted as the marginal benefit of x


The righthand side is the marginal cost of pollution to the merged firm.

At the optimum, the marginal "benefit" of pollution equals its marginal cost

In the merged firm, pollution is only produced up to the point that marginal reduction in steel firm cost is positive


In the independent firm, pollution was produced by the steel firm up to the point at which marginal reduction in the steel form cost was 0


The merged firm produced less pollution than the independent steel firm

The first order condition gives Screen Shot 2018-01-23 at 9.21.02 pm
This is to say: the firm will produce pollution until the marginal "benefit" of pollution equals its cost (the tax rate)

To achieve the same level of x, the government can set Screen Shot 2018-01-23 at 9.25.18 pm
This is a Pigouvian tax - a tax on the externality calibrated to achieve the Pareto efficient output of the externality

Correcting the externality: creating a market

Suppose the government gives property rights over pollution to the fishery. In other words, government mandates that the fishery has the right to zero pollution

Then for the steel firm Screen Shot 2018-01-23 at 9.45.43 pm

for the fihery Screen Shot 2018-01-23 at 9.46.02 pm

One of the first order conditions gives Screen Shot 2018-01-23 at 9.46.36 pm

That is, px is chosen will be the same as the one chosen by the megred firm and will be Pareto efficient

If the property rights are instead given to the steel firm, how much would the fishery be willing to pay for pollution reduction

Suppose the government states that the steel firm has the right to produce x-bar units of pollution

for the steel firm Screen Shot 2018-01-23 at 9.56.38 pm

for the fishery Screen Shot 2018-01-23 at 9.56.43 pm

FOCs the same as when the property rights over pollution were held by the fishery

Coase Theorem

If property rights are well defined, then under certain conditions, a market for the externality will result in the Pareto effcient allocation of the externality regardless of who hold the property rights

Notice that while x* is the same regardless of who holds the property rights, π s and π f are not the same


Higher profits will be realised by the party that holds the property rights

The problem with externalities is the absence of a market for them


If property rights are defined by the government, a market can arise to correct the externality

Positive externalities

If firms are independent, the positive externality is underproduced relative to the efficient allocation

A Pigouvian subsidy can correct the problem

If property rights over the externality are well defined, a market can arise for the externality that can correct the problem