What is 'public goods' and how do markets fail to provide them efficiently?

• A. Goods non-excludable and non-rivalrous; markets underprovide due to free-rider problems; require public policy.
• B. Goods that are sold exclusively to the wealthy.
• C. Goods that are only produced by private firms.
• D. Goods that always yield perfect competition.

Answer: (A)

Public goods are goods that are non-excludable and non-rivalrous. That means once the good is provided, you can’t easily prevent people from using it, and one person’s use doesn’t reduce another’s. Because of this, individuals have little incentive to pay for them—they can benefit without contributing, a free-rider problem. In a competitive market, this leads to underprovision, since firms can’t easily earn revenue from users. Socially, the quantity supplied falls short of the optimal level, so public policy or government funding is often needed to ensure adequate provision. Examples include national defense, street lighting, and certain knowledge—where benefits are widely shared and charging each user is impractical. The other options miss the defining feature: wealth-based access, private-only production, or the idea of perfect competition, none of which captures why public goods pose a market failure.