Editing Public good (section)

=== Challenges in identifying public goods ===
The definition of non-excludability states that it is impossible to exclude individuals from consumption. Technology now allows radio or TV broadcasts to be encrypted such that persons without a special decoder are excluded from the broadcast. Many forms of [[information good]]s have characteristics of public goods. For example, a poem can be read by many people without reducing the consumption of that good by others; in this sense, it is non-rivalrous. Similarly, the information in most patents can be used by any party without reducing consumption of that good by others. [[Official statistics]] provide a clear example of information goods that are public goods, since they are created to be non-excludable.  Creative works may be excludable in some circumstances, however: the individual who wrote the poem may decline to share it with others by not publishing it. [[Copyright]]s and [[patent]]s both encourage the creation of such non-rival goods by providing temporary monopolies, or, in the terminology of public goods, providing a legal mechanism to enforce excludability for a limited period of time. For public goods, the "lost revenue" of the producer of the good is not part of the definition: a public good is a good whose consumption does not reduce any other's consumption of that good.<ref>{{cite journal |last=Demsetz |first=Harold |title=Full Access The Private Production of Public Goods |journal=Journal of Law and Economics |date=October 1970 |volume=13 |issue=2 |pages=293–306 |jstor=229060 |doi=10.1086/466695|s2cid=154885952 }}</ref> Public goods also incorporate private goods, which makes it challenging to define what is private or public. For instance, one may think that the community soccer field is a public good. However, one needs to bring one's own cleats and ball to be able to play. There is also a rental fee that one would have to pay for one to be able to occupy that space. It is a mixed case of public and private good.

Debate has been generated among economists whether such a category of "public goods" exists. [[Steven Shavell]] has suggested the following:
<blockquote>when professional economists talk about public goods they do ''not'' mean that there are a general category of goods that share the same economic characteristics, manifest the same dysfunctions, and that may thus benefit from pretty similar corrective solutions...there is merely an infinite series of particular problems (some of [[overproduction]], some of underproduction, and so on), each with a particular solution that cannot be deduced from the theory, but that instead would depend on local empirical factors.<ref>{{cite book |last=Boyle |first=James |title=Shamans, Software, and Spleens: Law and the Construction of the Information Society |year=1996 |publisher=Harvard University Press |location=Cambridge, Mass. |isbn=978-0-674-80522-4 |pages=[https://archive.org/details/shamanssoftwares00boyl/page/268 268] |url-access=registration |url=https://archive.org/details/shamanssoftwares00boyl/page/268 }}</ref></blockquote>

There is a common misconception that public goods are goods provided by the [[public sector]]. Although it is often the case that government is involved in producing public goods, this is not always true. Public goods may be ''naturally'' available, or they may be produced by private individuals, by firms, or by non-state groups, called [[collective action]].<ref name="Touffut 2006 p. 26">{{cite book |last=Touffut |first=J.P. |title=Advancing Public Goods |publisher=Edward Elgar Publishing, Incorporated |series=The Cournot Centre for Economic Studies |year=2006 |isbn=978-1-84720-184-3 |url=https://books.google.com/books?id=HW_KRCi4T_0C&pg=PA26 |access-date=27 August 2018 |page=26}}</ref>

The theoretical concept of public goods does not distinguish geographic region in regards to how a good may be produced or consumed. However, some theorists, such as [[Inge Kaul]], use the term "[[global public good]]" for a public good that is non-rivalrous and non-excludable throughout the whole world, as opposed to a public good that exists in just one national area. Knowledge has been argued as an example of a global public good,<ref name="ReferenceA"/> but also as a commons, the [[knowledge commons]].<ref name="ostrom">{{cite book |title=Understanding Knowledge as a Commons: From Theory to Practice |last=Hess |first=Charlotte |author2=Ostrom, Elinor |year=2007 |publisher=Massachusetts Institute of Technology |location=Cambridge |isbn=978-0-262-08357-7 |pages=12–13}}</ref>

[[File:Samuelson condition.png|thumb|Aggregate demand (ΣMB) is the sum of individual demands (MBi)]]
Graphically, non-rivalry means that if each of several individuals has a demand curve for a public good, then the individual demand curves are summed vertically to get the aggregate demand curve for the public good. This is in contrast to the procedure for deriving the aggregate demand for a private good, where individual demands are summed horizontally.

Some writers have used the term "public good" to refer only to non-excludable "pure public goods" and refer to excludable public goods as "[[club goods]]".<ref>{{cite journal |author=James M. Buchanan |author-link=James M. Buchanan |title=An Economic Theory of Clubs |journal=[[Economica]] |date=February 1965 |volume=32 |pages=1–14 |doi=10.2307/2552442 |issue=125 |jstor=2552442}}</ref>