Rivalry, Excludability, and Durability

A good is rival if the fact that one person consumes a unit of it automatically means that no one can consume that unit at the same time, without incurring the cost of producing more. On the other hand, with a non-rival good the fact that one consumes a unit of the good means that it is automatically available for others to consume, without additional production cost.

A good is excludable if a unit of it exists, but consumers who want to use it can be prevented from doing so. It is non-excludable if one cannot be prevented from using it.

A non-rival, non-excludable good is called a public good.

A good is durable if the fact that it can be used now means that it can be used again for some time into the future.

Information is non-rival, physically non-excludable, and durable. Intellectual property is a legal device to make information excludable.

1. An radio broadcast is not durable. Explain why, briefly.
2. An apple is rival. Explain why, briefly.
3. Give an example of a good that you use that is durable. Explain why it is durable, briefly.
4. Give an example of a good that you use that is non-rival. Explain why it is not rival, briefly.
5. Give an example of a good that you use that is non-excludable. Explain why it is not excludable, briefly.

Your answers to 3, 4, and 5 should be different goods.