經濟學 1990

公共事物的治理之道：集體行動制度的演進

埃莉諾·歐斯壯

社群能自己治理共享之物——既不必賣掉，也不必交給國家。

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In depth · the introduction

如果那個著名的「公地悲劇」——說共享一片牧場或一處漁場的人，終將把它毀掉——根本就不成立呢？

核心想法

幾十年裡，教科書的說法都很決絕：任何人人可用、卻無人擁有的資源，注定要完蛋。每個人都趕在別人之前盡量多拿，於是共享的牧場、漁場或森林被毀掉。能提供的解藥只有兩種：把它圍起來賣掉（私有化），或者交給政府來管。

埃莉諾·歐斯壯，則去實地看了看。她走訪一個個真實的社群——瑞士的山村、日本的森林、西班牙的灌溉網、菲律賓的水渠——發現有些共享資源，被它們自己的使用者可持續地經營了數百年。靠這資源吃飯的人，悄悄地發明了自己的規則，彼此盯著看大家是否遵守，並處置那些占便宜的人。原來，第三條路一直都在。

它是如何誕生的

歐斯壯受的是政治學訓練，而那時的經濟學，正越來越把人模型化為孤立的自利最大化者。她與丈夫文森特，以及印第安納大學布魯明頓研究院的同事們，花了數十年，蒐集真實社群如何治理水、魚、牧場與森林的田野研究。1990 年的《公共事物的治理之道》，把這些證據提煉成一個論證和一套設計原則。

2009 年，這項工作為她贏得諾貝爾經濟學獎——史上第一位女性得主——「以表彰她對經濟治理、尤其是公地的分析」。這一抉擇讓許多經濟學家意外：歐斯壯是政治學家，她的結論來自耐心的田野、而非方程式；她的獲獎，也拓寬了這門學科所認可的「證據」之邊界。

它為何重要

它推翻了一條曾左右現實政策的常識——這條常識曾被用來為「把村莊土地私有化、把森林與漁場收歸國有」辯護，而那樣做，有時恰恰毀掉了一直讓這些資源保持健康的本地制度。歐斯壯表明：社群往往是它們共享之物的最佳守護者；她還給改革者一份具體的清單：自主治理在什麼情形下可能奏效。

一個可以想像的畫面

想像合租公寓裡一個共用的廚房。若誰都不肯商量，水槽裡堆滿碗碟、牛奶總是不翼而飛——這就是縮小版的公地悲劇。但大多數合租屋並不會就此崩壞：室友們排出一張值日表，留意誰在偷懶，並在有人屢屢占便宜時先輕聲提醒、再正色相告。無需房東，也無需變賣——只要清晰的邊界、共享的規則、彼此的注視，和與過錯相稱的後果。把這一切放大，正是歐斯壯看到的、把森林與漁場維繫了數百年的東西。

它的位置

歐斯壯的公地，正面對峙著加勒特·哈丁 1968 年的「公地悲劇」，也對峙著博弈論囚徒困境裡那種孤立、純然自利的行動者（參見本館的約翰·納許）。亞當·斯密揭示了自利如何能被市場所引導，凱因斯指出了市場何處需要國家，而歐斯壯勾勒出第三個領域——社群為自己搭建的制度——並以此重塑了氣候變遷時代的環境與發展政策。

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Original source text

Elinor Ostrom · Cambridge University Press (1990) · series: The Political Economy of Institutions and Decisions

Chapter 1 — Reflections on the commons

Ostrom opens by confronting three influential models that all forecast ruin for shared resources: Garrett Hardin’s “tragedy of the commons” (Science, 1968), the prisoner’s dilemma, and Mancur Olson’s logic of collective action. Each concludes that self-interested users, left to themselves, must over-harvest a commons to destruction.

Freedom in a commons brings ruin to all. — Garrett Hardin, Science 162 (1968), the conclusion Ostrom sets out to test.

Chapter 2 — An institutional approach to self-organisation and self-governance

She defines a common-pool resource (CPR) as one from which excluding users is costly, yet from which each unit harvested is no longer available to anyone else. The question is reframed: not “market or state?” but how appropriators can supply themselves with their own institutions — rules they make, monitor and enforce.

Chapter 3 — Analysing long-enduring, self-organised, and self-governed CPRs

The empirical heart of the book examines resources governed sustainably by their users for generations: the high-mountain meadows and forests of Törbel in Switzerland; village commons in Japan; the huerta irrigation institutions of Valencia, Murcia, Orihuela and Alicante in Spain; and the farmer-built zanjera irrigation communities of the Philippines. From these she abstracts eight design principles shared by robust, long-lived commons (Table 3.1).

Clearly defined boundaries: Individuals or households who have rights to withdraw resource units from the CPR must be clearly defined, as must the boundaries of the CPR itself. — Ostrom, Table 3.1, design principle 1.

The remaining principles, in brief: (2) rules matched to local conditions; (3) collective-choice arrangements, so those affected can change the rules; (4) monitoring by monitors accountable to the users; (5) graduated sanctions for violations; (6) low-cost conflict-resolution mechanisms; (7) minimal recognition by external authorities of the right to organise; and, for larger systems, (8) nested enterprises — governance organised in multiple layers.

Chapters 4–6 — Institutional change, fragility, and a framework for analysis

Later chapters examine how such institutions arise and change, and why some fail — among the failures, several California groundwater basins and certain coastal fisheries — before proposing a framework for analysing self-organising and self-governing common-pool resources.

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Workshop in Political Theory and Policy Analysis, Indiana University · 1990