Full Title: Provision Problem of Public Goods – Part 4- [Article No. 2.4.4]
日本語タイトル：公共財の供給問題- Part 4- [記事 No. 2.4.4]
Posted on June 16, 2026.
[Image]
(In Japanese)
Note: For a more detailed discussion of public goods, please consult textbooks on public economics at the intermediate level or higher.
（注）公共財の詳細については，中級以上の公共経済学のテキストをご覧ください．
Source: By Yoshida.
[Discussion]
- 公共財に関して，Free-rider 問題が発生しLindahl 均衡が実現できない場合，政府が次善の策として，各個人の費用負担を均等化させるとしよう．この場合，一般的には，Image 1 で示す通り，社会の構成員の内誰一人として，社会的に効率的な公共財供給量を望まないという結果となる*．すなわち，どの個人も政府の仕事量を「過剰」もしくは「過少」としか評価しないという状況が生まれる．（Free-rider 問題，Lindahl 均衡については [記事 No. 2.4.3]を参照されたい）．
(*) なお，各個人の経済力に応じて費用負担を重くする方法も考えられる．しかし，各個人が欲する公共財供給量は変化するものの，この場合でも上記した一般的な結果は覆らない．
2. 上記１で説明した事実は，政府運営の原理的な難しさを示している．なお，この公共財供給問題は混合経済（参照： [記事 No. 2.3.1-3]）運営の一部分に過ぎない．現実の社会は混合経済であるため，資源配分にとって極めて便利な「市場」というツールを使うだけでは適切な社会運営を実施することはできない．こうした事実を踏まえた場合，政府の仕事を適切に運営するためには相応の能力，慎重さ，誠実さが必要となることが明らかであろう．
- Suppose that the free-rider problem arises with respect to a public good, preventing the achievement of a Lindahl equilibrium. In this case, assume that the government equalizes the cost burden among individuals as a second-best solution. As shown in Image 1, the general result under this scenario is that no member of society desires the socially efficient level of public good supply*. In other words, every individual will view the government’s expenditure as either “excessive” or “insufficient.” (For more on the free-rider problem and the Lindahl equilibrium, see [Article No. 2.4.3]).
(*) Alternatively, a progressive cost burden could be introduced based on each individual’s economic capacity. However, although the quantity of the public good desired by each individual would change, the general result described above remains unchanged.
2. The facts described in Item 1 above illustrate the fundamental difficulties inherent in government administration. It should be noted that this issue of public goods provision is merely one aspect of managing a mixed economy (see [Article No. 2.3.1-3]). Since a real society is a mixed economy, it is not possible to achieve proper social management by relying solely on the market, a tool that is extremely useful for resource allocation. Given these facts, it is clear that appropriate capability, prudence, and integrity are necessary to carry out the government’s duties effectively.
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