Final answer:
Public goods like national defense and air quality are inherently non-excludable and non-rival, available to all without charge, which leads to the free rider problem. Purposive benefits are not public goods because the provision of public goods typically cannot be restricted to those who pay. Private goods, in contrast, are excludable and rival, allowing private firms to charge users and exclude non-payers.
Step-by-step explanation:
Purposive benefits are not essentially public goods because public goods are distinct in their non-excludable and non-rival nature. Unlike private goods, public goods are available to all members of the public regardless of individual contributions, leading to the free rider problem. This problem arises because individuals can benefit from the goods or services without paying for them, and it is either impossible or very costly to exclude non-payers from consumption. As a result, when such goods are privately provided, there is a tendency for them to be under-produced relative to the socially optimal level, because private companies cannot effectively charge and exclude non-payers.
For example, national defense is a classic public good; it protects all citizens and cannot reasonably be provided on a private, exclusionary basis. Similarly, other services like air quality or national parks exhibit characteristics that make privatized provision challenging, as they provide widespread societal benefits that are not confined to the paying users. In contrast, private goods can be both excludable and rivalrous, meaning firms can charge for their use, and consumption by one individual typically prevents simultaneous consumption by others, unlike public goods.
In some instances, positive externalities may be present in both private and public goods, but this alone does not make a good or service a public good. Private companies can still produce goods with positive externalities, like education or technological innovations, and maintain exclusivity and profit from them.