《佃農理論》的貢獻

早前參加張五常教授的《佃農理論》四十週年研討會,不少講者大談《佃農理論》的貢獻。慚愧的是,我接觸的《佃農理論》只是在張教授的英語論文選(Economic Explanation, Selected Papers of Steven N. S. Cheung)之中,僅為《佃農理論》部分章節。近日細讀《佃農理論》全文,雖未完成,但認為該文最大貢獻乃在思考方法之上。

對於佃農分成缺乏效率之說,源自抽稅之分析,由於分成有如政府抽稅,必然引致生產要素投入不足。這種理論在數理上無懈可擊,容易造成思想盲點,不過張教授卻指出其要害:

“Third, with a tax, the government is not contracting to maximize wealth.  In other words, the tax-equivalent analysis fails to offer any explicit treatment of the terms in a share contract which the participating parties must mutually agree to abide by when the contract is formed.”

既然佃農分成安排需要雙方同意,假如安排確實缺乏效率、影響一方收入,又何能長久存在﹖

當然,其後找出土地面積、分成率等合約中的關鍵變項,從而在理論上證明分成與其他合約安排具相同效率,是非常重要的部分。不過,這種以邏輯推論引領思考方向的示範,我認為是對於後世最大的貢獻。

現時的經濟研究,太過熱衷於「發現」現象(特別是「失效」現象),在數理模型中推得無懈可擊,往往卻未能對現象因何出現、因何長存提出合理解釋,這的確是一個遺憾。

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2 Responses to 《佃農理論》的貢獻

  1. kempton says:

    Interesting insight. Thanks for sharing Aries.

  2. Angel-a says:

    I agree, Aries.
    Share contract, to me, is a “rent contract” – the peasants “rent” the land from the landlords, and in return, pay a share of proceeds to the landlord like we pay our rent for renting an apartment.

    The ownership of property is clearly defined, and the two parties enter the contract with a mutual agreement as how much their properties (land and labor) are worth.

    It is never the case with taxes.

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