What is a Public Good?

Even though new technology creates positive externalities so that perhaps one-third or one-half of the social benefit of new inventions spills over to others, the inventor still receives some private return. What about a situation where the positive externalities are so extensive that private firms could not expect to receive any of the social benefit? We call this kind of good a public good. Spending on national defense is a good example of a public good. Let’s begin by defining the characteristics of a public good and discussing why these characteristics make it difficult for private firms to supply public goods. Then we will see how government may step in to address the issue.

Economists have a strict definition of a public good, and it does not necessarily include all goods financed through taxes. To understand the defining characteristics of a public good, first consider an ordinary private good, like a piece of pizza. We can buy and sell a piece of pizza fairly easily because it is a separate and identifiable item. However, public goods are not separate and identifiable in this way.

Related Topics

• Market Competition and Innovation
• New Technology and Positive Externalities

• Externality
• Network Externality
• Pigovian Tax
• Coase Theorem
• Agglomeration Diseconomies

• Education - Private and Social Rate of Return
• Government Approaches to Encouraging Innovation
• Public Good
• Public, Private, Club, Common Goods
• Excludable and Rivalrous Goods
• What is the Free Rider Problem for Public Goods?
• Free Rider
• Social Loafing
• Role of Government in Paying for Public Goods
• What is the Tragedy of Commons for Common Resources?
• Income Inequality
• Poverty Line?
• Poverty Trap
• Public Safety Net
• Measuring Income Inequality
• Lorenz Curve
• Ladder of Opportunity
• Tradeoff between Incentives and Income Equality