The characteristics of public goods and private goods

Public goods are items or services that are consumed collectively. The under-provision of public goods is an important example of market failure and one of the main reasons for government intervention.

Public goods

Public goods have two main characteristics:

Key characteristics:

• Non-excludability - It is impossible to prevent individuals from using the good, even if they have not paid for it. For instance, you couldn't stop an individual benefiting from national defence services.
• Non-rivalry (or non-diminishability) - One person's use of the good does not reduce its availability or benefit to others. An example is more people benefiting from public parks doesn't reduce the benefit to the first person.

Additional features:

• Zero marginal cost - There is no additional cost to extending the good to one more person.
• Non-rejectability - Individuals cannot opt out of benefiting from the good. For example, you can't choose to not be protected by national defence, as they'll do it anyway.

Other examples of public goods include community festivals and navigation beacons for ships.

Private goods

Private goods are the opposite of public goods.

• Excludability - It is possible to prevent non-payers from accessing the good. For example, a sandwich is a private good, and if you eat it, you stop anyone else from eating it.
• Rivalry - One person's consumption reduces or eliminates the good's availability for others.
• Consumer choice - Unlike public goods, people have a choice as to whether to consume private goods.

Most everyday items, such as groceries or higher education, fall into this category.

Quasi-public goods and how technology can change their characteristics

Not all public goods are purely public; some can display mixed traits and may even shift towards private good characteristics over time.

Quasi-public goods

Some goods are pure public goods, while others are known as non-pure (or quasi) public goods.

Highways as quasi-public goods:

• They appear non-excludable when free to use and non-rivalrous, as one person using a highway doesn't prevent another person from using it too.
• However, toll systems can make a highway excludable by excluding those who don't pay to use it.
• Congestion will make a highway exhibit rivalry, as there's a limit to the number of people who can benefit at any one time.

Impact of technology on public goods

New technology can change a good that once had the characteristics of a public good into a private good.

• Traditional radio broadcasts have some characteristics of a public good, being non-rivalrous and non-excludable.
• However, the invention of digital technology has meant that channels can be encrypted to ensure that if people want a certain channel, they have to pay for it.

Under-provision of public goods in the free market

In a free market, public goods are often not supplied adequately because private firms lack incentives to produce them, resulting in market failure.

The free rider problem

The non-excludability of public goods leads to the free rider problem. Once a public good is provided, it's impossible to stop someone from benefiting from it, even if they haven't paid. For example, a company providing public waste disposal cannot stop a free rider, who has refused to pay for waste disposal, benefiting from clean streets.

Why public goods are under-provided

• Failure of the price mechanism - The price mechanism cannot work if there are free riders. Consumers won't choose to pay for a public good that they can get for free because other consumers have paid for it. If everyone decides to wait and see who will provide and pay for a public good, then it won't be provided.
• Challenges in pricing - It's difficult to set a price for public goods because it's difficult to work out their value to consumers. Producers will tend to overvalue the benefits of a public good to increase the price they charge, while consumers will undervalue their benefits to try to get a lower price.
• Reluctance from firms - These problems mean that firms are reluctant to supply public goods, causing market failure.

Positive externalities are a form of public good that are consumed by those who don't pay for them, so they're an example of the free rider problem.

Environmental resources as public goods

Certain environmental elements function as public goods, which can lead to overuse and degradation without proper management.

Clean air as a public good

Clean air is a public good which isn't bought and sold on a market. It's non-excludable and non-rivalrous.

• Both clean air and dirty, polluted air cost the same (nothing), so if clean air becomes scarce its price won't rise and deter people from "using it up."
• The non-excludability of clean air leads to the free rider problem.
• The benefits of not polluting the air aren't restricted to those who have "paid" for the clean air by choosing not to pollute.
• Therefore, in the free market, it's unlikely that anyone will either choose not to pollute, or to clean up the pollution they make.

The tragedy of the commons

This concept explains how shared resources are often misused. This is the idea that people acting in their own best interests will overuse a common resource without considering that this will lead to the depletion or degradation of that resource. The tragedy of the commons can explain many causes of environmental market failure.

The free rider problem and government intervention

The free rider problem is central to why public goods are under-provided, prompting governments to take action to correct market failures.

Consequences of the free rider problem

• It prevents efficient provision, as people benefit without contributing, discouraging investment in public goods like clean environments or defence.
• In environmental contexts, it leads to pollution because the benefits of not polluting are shared, but costs are individual.

Methods of government intervention

Governments will usually have to intervene to prevent the destruction and degradation of common resources.

• Taxation - Taxes on polluters discourage harmful activities and fund cleanup efforts.
• Subsidies - Financial incentives encourage behaviours that preserve public goods, such as grants for renewable energy.
• Legislation - Laws set standards, like emission limits, to prevent overuse of resources.
• Direct spending - Governments fund public goods directly, such as building parks or providing national defence, to overcome free market shortcomings.