Public good (economics)
In economics, a public good (also referred to as a social good or collective good)[1] is a good that is both non-excludable and non-rivalrous. Use by one person neither prevents access by other people, nor does it reduce availability to others.[1] Therefore, the good can be used simultaneously by more than one person.[2] This is in contrast to a common good, such as wild fish stocks in the ocean, which is non-excludable but rivalrous to a certain degree. If too many fish were harvested, the stocks would deplete, limiting the access of fish for others. A public good must be valuable to more than one user, otherwise, its simultaneous availability to more than one person would be economically irrelevant.
For the general concept, see Common good.
Capital goods may be used to produce public goods or services that are "...typically provided on a large scale to many consumers."[3] Similarly, using capital goods to produce public goods may result in the creation of new capital goods. In some cases, public goods or services are considered "...insufficiently profitable to be provided by the private sector.... (and), in the absence of government provision, these goods or services would be produced in relatively small quantities or, perhaps, not at all."[3]
Public goods include knowledge,[4] official statistics, national security, common languages,[5] law enforcement, public parks, free roads, and many television and radio broadcasts.[6] Flood control systems, lighthouses, and street lighting are also common social goods. Collective goods that are spread all over the face of the Earth may be referred to as global public goods. This includes physical book literature, but also media, pictures and videos.[7] For instance, knowledge is well shared globally. Information about men's, women's and youth health awareness, environmental issues, and maintaining biodiversity is common knowledge that every individual in the society can get without necessarily preventing others access. Also, sharing and interpreting contemporary history with a cultural lexicon (particularly about protected cultural heritage sites and monuments) is another source of knowledge that the people can freely access.
Public goods problems are often closely related to the "free-rider" problem, in which people not paying for the good may continue to access it. Thus, the good may be under-produced, overused or degraded.[8] Public goods may also become subject to restrictions on access and may then be considered to be club goods; exclusion mechanisms include toll roads, congestion pricing, and pay television with an encoded signal that can be decrypted only by paid subscribers.
There is a good deal of debate and literature on how to measure the significance of public goods problems in an economy, and to identify the best remedies.
Efficient production levels of public goods[edit]
The socially optimal provision of a public good in a society occurs when the sum of the marginal valuations of the public good (taken across all individuals) is equal to the marginal cost of providing that public good. These marginal valuations are, formally, marginal rates of substitution relative to some reference private good, and the marginal cost is a marginal rate of transformation that describes how much of that private good it costs to produce an incremental unit of the public good. This contrasts to the social optimality condition of private goods, which equates each consumer's valuation of the private good to its marginal cost of production.[9][40]
For an example, consider a community of just two consumers and the government is considering whether or not to build a public park. One person is prepared to pay up to $200 for its use, while the other is willing to pay up to $100. The total value to the two individuals of having the park is $300. If it can be produced for $225, there is a $75 surplus to maintaining the park, since it provides services that the community values at $300 at a cost of only $225.
The classical theory of public goods defines efficiency under idealized conditions of complete information, a situation already acknowledged in Wicksell (1896).[41] Samuelson emphasized that this poses problems for the efficient provision of public goods in practice and the assessment of an efficient Lindahl tax to finance public goods, because individuals have incentives to underreport how much they value public goods.[9] Subsequent work, especially in mechanism design and the theory of public finance developed how valuations and costs could actually be elicited in practical conditions of incomplete information, using devices such as the Vickrey–Clarke–Groves mechanism. Thus, deeper analysis of problems of public goods motivated much work that is at the heart of modern economic theory.[42]
Local public goods[edit]
The basic theory of public goods as discussed above begins with situations where the level of a public good (e.g., quality of the air) is equally experienced by everyone. However, in many important situations of interest, the incidence of benefits and costs is not so simple. For example, when people keep an office clean or monitor a neighborhood for signs of trouble, the benefits of that effort accrue to some people (those in their neighborhoods) more than to others. The overlapping structure of these neighborhoods is often modeled as a network.[43] (When neighborhoods are totally separate, i.e., non-overlapping, the standard model is the Tiebout model.)
An example of locally public good that could help everyone, even ones not from the neighborhood, is a bus. Let's say you are a college student who is visiting their friend who goes to school in another city. You get to benefit from this services just like everyone that resides and goes to school in said city. There is also a correlation of benefit and cost that you are now a part of. You are benefiting by not having to walk to your destination and taking a bus instead. However, others might prefer to walk so they do not become a part of the problem, which is pollution due to gas given out by auto mobiles.
Recently, economists have developed the theory of local public goods with overlapping neighborhoods, or public goods in networks: both their efficient provision, and how much can be provided voluntarily in a non-cooperative equilibrium. When it comes to socially efficient provision, networks that are more dense or close-knit in terms of how much people can benefit each other have more scope for improving on an inefficient status quo.[44] On the other hand, voluntary provision is typically below the efficient level, and equilibrium outcomes tend to involve strong specialization, with a few individuals contributing heavily and their neighbors free-riding on those contributions.[43][45]
Ownership[edit]
Economic theorists such as Oliver Hart (1995) have emphasized that ownership matters for investment incentives when contracts are incomplete.[46] The incomplete contracting paradigm has been applied to public goods by Besley and Ghatak (2001).[47] They consider the government and a non-governmental organization (NGO) who can both make investments to provide a public good. Besley and Ghatak argue that the party who has a larger valuation of the public good should be the owner, regardless of whether the government or the NGO has a better investment technology. This result contrasts with the case of private goods studied by Hart (1995), where the party with the better investment technology should be the owner. However, it has been shown that the investment technology may matter also in the public-good case when a party is indispensable or when there are bargaining frictions between the government and the NGO.[48][49] Halonen-Akatwijuka and Pafilis (2020) have demonstrated that Besley and Ghatak's results are not robust when there is a long-term relationship, such that the parties interact repeatedly.[50] Moreover, Schmitz (2021) has shown that when the parties have private information about their valuations of the public good, then the investment technology can be an important determinant of the optimal ownership structure.[51]