The meaning and types of market failure

Market failure happens when the allocation of resources in a market is inefficient, leading to a net loss of welfare for society. This inefficiency arises because the price mechanism, driven by supply and demand, does not always guide resources to their best use, often resulting in either too much or too little of a good or service being produced or consumed.

Market failure stems from the price mechanism failing to reflect all costs and benefits accurately, which can harm society overall.

Complete market failure

Complete market failure exists when no market forms at all, creating what is known as a missing market. Public safety, such as national defence or street lighting, lacks a natural market because benefits are shared widely and cannot easily be restricted to paying customers.

Partial market failure

Partial market failure occurs when a market does exist, but it produces or consumes either the wrong quantity or at the wrong price, leading to inefficiency. Public transport might be under-provided if left solely to market forces, as private firms focus on profit, potentially pricing out low-income users who need it for access to work or education.

Positive and negative externalities in production and consumption

Externalities are spillover effects from the production or consumption of a good or service that impact third parties who are not directly involved in the transaction. These effects are not reflected in the market price, leading to market failure.

Positive externalities

Positive externalities provide benefits to third parties without compensation:

• Positive production externalities - These occur during the creation of a good, such as when a firm develops solar panels, leading to broader advancements in renewable energy that benefit society through reduced reliance on fossil fuels.
• Positive consumption externalities - These arise from using a good, for example, when an individual trains as a paramedic, society gains from improved emergency response capabilities and overall public health.

Negative externalities

Negative externalities impose costs on third parties without reimbursement:

• Negative production externalities - These happen in manufacturing, like a chemical factory causing air pollution that damages local wildlife and human health in the surrounding area.
• Negative consumption externalities - These result from use, such as smoking leading to litter from discarded cigarette butts that pollutes streets and harms the environment.

The relationship between private costs/benefits and social costs/benefits

In a free market, decisions are based only on private costs and benefits, ignoring externalities. This mismatch causes market failure, as the true impact on society is not considered.

Private and social costs

• Private costs - Expenses borne directly by producers or consumers, such as wages or raw materials for a firm.
• External costs - Additional burdens on third parties from negative externalities, like health issues from pollution.
• Social costs - The total cost to society, combining private and external costs.

$\text{Social cost}=\text{private cost}+\text{external cost}$

Private and social benefits

• Private benefits - Gains directly received by producers or consumers, such as profit from sales or personal satisfaction from a purchase.
• External benefits - Additional advantages to third parties from positive externalities, like community health improvements from widespread vaccination.
• Social benefits - The full benefit to society, including both private and external benefits.

$\text{Social benefit}=\text{private benefit}+\text{external benefit}$

Market failure arises because free markets focus solely on private elements, overlooking external ones and thus not achieving the socially optimal outcome.

Externalities shown in diagrams

Diagrams help illustrate how externalities create a gap between private and social costs or benefits, leading to inefficient market outcomes. The curves represent marginal (per additional unit) values.

Marginal costs in production externalities

• Marginal private cost (MPC) - The cost to the producer of making one more unit.
• Marginal social cost (MSC) - Includes external costs from negative externalities.

$\text{MSC}=\text{MPC}+\text{external cost}$

• The gap between MPC and MSC shows negative externalities.
• If curves are parallel, external costs per unit are constant.
• If diverging, external costs rise with output (e.g., escalating pollution damage as production increases).

Marginal benefits in consumption externalities

• Marginal private benefit (MPB) - The benefit to the consumer from one more unit.
• Marginal social benefit (MSB) - Includes external benefits from positive externalities.

$\text{MSB}=\text{MPB}+\text{external benefit}$

• The gap between MPB and MSB shows positive externalities.
• If curves are parallel, external benefits per unit are constant.
• If diverging, external benefits increase with consumption (e.g., greater herd immunity from more vaccinations).

In diagrams, MPC often acts as the supply curve, and MPB as the demand curve.

Equilibrium compared to socially optimal output in different externality scenarios

Free market equilibrium occurs where MPC equals MPB, based only on private factors. However, the socially optimal output is where MSC equals MSB, accounting for externalities to maximise societal welfare.

Negative production externalities leading to overproduction

Negative production externalities cause overproduction and underpricing, as firms ignore external costs:

• Equilibrium output exceeds the social optimum.
• For units between optimal and market output, MSC > MSB, creating a welfare loss (area between MSC and MSB curves).
• Example - A factory dumping waste into rivers ignores environmental harm, producing more than socially desirable and causing societal loss through polluted water sources.

Positive consumption externalities leading to underconsumption

Positive consumption externalities result in underconsumption and underpricing, as consumers ignore external benefits:

• Market quantity is below the social optimum.
• For units between market and optimal quantity, MSB > MSC, representing a potential welfare gain (area between MSB and MSC curves).
• Example in education - Students and providers focus on personal gains like better jobs, ignoring societal benefits such as a more productive workforce or lower crime rates, leading to less education than optimal.
• Example in healthcare - Decisions ignore broader gains like a healthier, more productive population and increased life expectancy, resulting in under-provision.

Negative consumption externalities leading to overconsumption

Negative consumption externalities lead to overconsumption and overpricing, as users ignore external costs:

• Market quantity surpasses the social optimum.
• For units between optimal and market quantity, MSC > MSB, causing a welfare loss.
• Example - Drivers ignore pollution and congestion from car use, leading to excessive vehicle usage that reduces productivity through traffic delays.

Positive production externalities leading to underproduction

Positive production externalities cause underproduction and overpricing, as firms ignore external benefits:

• Market output is below the social optimum.
• For units between market and optimal quantity, MSB > MSC, indicating a potential welfare gain.
• Example - Firms under-invest in staff training, missing societal benefits like a more skilled workforce that boosts overall economic output.