What is a common resource and how does it differ from a public good?

What is a common resource and how does it differ from a public good?

• A. Common resources are non-rival and non-excludable; public goods are rival and excludable.
• B. Common resources are excludable and rival; public goods are non-excludable and non-rival.
• C. Common resources are rival but non-excludable; public goods are non-rival and non-excludable.
• D. Common resources are excludable and non-rival; public goods are excludable and rival.

Answer: (C)

Distinguishing between common resources and public goods hinges on how consumption affects others (rivalry) and how easy it is to exclude people from using them (excludability). Common resources are rival but non-excludable: one person’s use reduces what’s left for others, and it’s hard to prevent people from using them. A classic example is a fishery: catching fish lowers availability for everyone else, and there isn’t an easy way to bar non-payers from fishing. Public goods, by contrast, are non-rival and non-excludable: one person benefiting does not diminish another’s, and it’s hard to exclude anyone from benefiting. Think of national defense or a lighthouse: everyone in the area benefits, and you can’t realistically charge people separately or stop them from getting the benefit. So the statement that common resources are rival and non-excludable while public goods are non-rival and non-excludable best captures these concepts. The other descriptions mix up rivalness and excludability (for example, common resources are not typically excludable, while public goods are non-excludable).

Distinguishing between common resources and public goods hinges on how consumption affects others (rivalry) and how easy it is to exclude people from using them (excludability). Common resources are rival but non-excludable: one person’s use reduces what’s left for others, and it’s hard to prevent people from using them. A classic example is a fishery: catching fish lowers availability for everyone else, and there isn’t an easy way to bar non-payers from fishing. Public goods, by contrast, are non-rival and non-excludable: one person benefiting does not diminish another’s, and it’s hard to exclude anyone from benefiting. Think of national defense or a lighthouse: everyone in the area benefits, and you can’t realistically charge people separately or stop them from getting the benefit. So the statement that common resources are rival and non-excludable while public goods are non-rival and non-excludable best captures these concepts. The other descriptions mix up rivalness and excludability (for example, common resources are not typically excludable, while public goods are non-excludable).