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.

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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