Social Cost - Theory

Theory

The ideas of social cost, externalities, and market failure are often used as an argument for government intervention in the form of regulations. Libertarians who believe in a free market respond that the existence of market failure should not lead to government intervention. They prefer to rely on tradition, community pressure, and dollar voting.

Negative externalities (external costs) lead to an over-production of those goods that have a high social cost. For example, the logging of trees for timber may result in society losing a recreation area, shade, beauty, good quality soil to grow crops on, and air quality but this loss is usually not quantified and included in the price of the timber that is made from the trees. As a result, individual entities in the marketplace have no incentive to factor in these externalities. More of this activity is performed than would be if its cost had a true accounting.

This can be illustrated with a diagram. Profit-maximizing organizations will set output at Q_p where marginal private costs (MPC) is equal to marginal revenue (MR). (This diagram assumes perfect competition, under which price (P) equals MR.) This will yield a profit shown by the triangular area 0,C,F.

But if externalities are present, the attainment of social optimality requires that the full social costs must be considered. The socially optimum level of output is Q_s where marginal social costs (MSC) is equal to marginal revenue (MR). The amount of output, Q_p minus Q_s, indicates the excess output due to the externality. Profits will decrease also, from 0,C,F to 0,A,F. It is clearly profitable for the firm to pollute, since "internalizing the externality" hurts profits. The amount of the externality will decrease from C,D to B,A.

Because the marginal social cost curve (MSC) is above the marginal private cost curve (MPC), this diagram illustrates the case of a negative externality. If the marginal social cost curve was below the marginal private cost curve, it would be a positive externality and social optimality would require a greater output than Q_p rather than a reduction of output.

Institutional ecological economists in the tradition of Karl William Kapp provide a different definition of social costs, i.e. that share of the total costs of production that is not born by producers but is shifted to 3rd parties, future generations or society at large. Kapp, hence, rejected Pigou's confusing terminology of externalities and provides several hundred pages of empirical data to support his argument that social costs are systemic, i.e. rooted in profit maximizing behavior of businesses, and an enormous problem of modern civilization. In the real world, they are usually not or cannot be internalized and must not be considered as accidental minor aberration from the "optimal norm" that can be fixed with ad hoc measures.