時間、相對所得與邊際效用遞減法則關係之探討

Time, Relative Income and Law of diminishing marginal utility

曹淑琳(Shuling Tsao)

《中科大學報》 6卷1期 (2019/12) Pp. 13-33

https://doi.org/10.6902/JNTUST.201912_6(1).0002

摘要

依據林忠正（2015，2016，2017）序列論文的研究，可以了解常用的「邊際效用遞減法則」不能在效用數值只能排序的序數總效用概念中取得一個容身之處。如何解決此效用理論的基本問題，一直沒有重要的進展。此項經濟理論上的重大缺陷，直到林忠正（2015，2016，2017）提出「序數邊際效用分析法」（ordinal marginal utility approach）才為「序數的邊際效用遞減法則」取得一個合理的理論定位。本文依據林忠正的「序數邊際效用分析法」，提出並討論一個關於「邊際效用遞減法則」的有趣問題。簡單地說，本文強調人們所得的邊際效用為「相對所得」的函數，「相對所得」取決於「實際所得」與「參考所得」的相對大小，此時，可以以「實際所得」與「參考所得」的「比例」方式來呈現「相對所得」的概念，而且在「邊際效用遞減法則」成立的情況下，「相對所得」愈高，消費者的邊際效用愈低，換句話說，效用取決於「相對所得」，也就是一人的幸福程度或效用取決於「實際所得」（實際狀態）與「參考所得」（參考點）的互相比較的概念。本文也要探討「參考所得為時間的函數，並會隨著時間的延伸而變化的概念」之觀點，也就是，當「實際所得」大於「參考所得」時，隨著時間的延伸，「參考所得」會向上調整而逐漸接近「實際所得」；當「實際所得」小於「參考所得」時，隨著時間的延伸，「參考所得」會向下調整而逐漸接近「實際所得」。藉由以上的論述，我們可以解釋以下的現象：隨著時間的經過，高估自己所得之人，會逐漸認清現實，其對於幸福的評價（亦即邊際效用）會因此隨著時間而逐漸增加，但各個年歲的幸福程度（亦即各時點總效用）卻會隨時間逐漸下降，而幸福評價與幸福程度都會隨著時間漸漸回復成與平常的狀態相差不遠，甚至是無差異的；反之，低估自己所得之人，其幸福變化，會隨著時間的經過，逐漸認清現實，其對於幸福的評價（亦即邊際效用）會因此隨著時間而逐漸下降，但各個年歲的幸福程度（亦即各時點總效用）卻會隨時間逐漸上升，而幸福評價與幸福程度都會隨著時間漸漸回復成與平常的狀態相差不遠，甚至是無差異的。因此，本文欲討論現代經濟理論中，未曾提出討論的「時間」、「相對所得」與「邊際效用遞減法則」之間微妙的關係。

關鍵字

時間 ； 相對所得 ； 實際所得 ； 邊際效用遞減法則

並列摘要

According to Lin (2015, 2016, 2017) series of dissertations, we can understand that the commonly used ＂Law of diminishing marginal utility＂ cannot obtain a place in the concept of total utility number ordinal that utility value can only sort. There is no significant progress in how to solve the basic problem of this utility theory. This major theoretical imperfection in economic theory, until Lin (2015, 2016, 2017) proposed that the ＂ordinal marginal utility approach＂ was to obtain a reasonable theoretical position for the ＂ordinal marginal utility reduction law.＂ Based on the ＂Ordinal Marginal Utility Analysis Method＂ put forward by Lin, this paper proposes and discusses an interesting question about ＂the law of diminishing marginal utility＂. To put it simply, this article emphasizes that people's marginal utility is a function of ＂relative income.＂ The relative income depends on the relative size of ＂actual income＂ and ＂reference income.＂ In this case, ＂actual income＂ and ＂reference income＂ can be used. The ＂proportional＂ approach is to present the concept of ＂relative income,＂ and in the case of the establishment of the ＂law of diminishing marginal utility＂, the higher the ＂relative income＂, the lower the marginal utility of consumers. This article also discusses new ideas of ＂reflecting the concept that income is a function of time and will change over time.＂ That is, when ＂actual income＂ is greater than ＂reference income, ＂ as time goes by, ＂reference income＂ will adjust upward and gradually approach ＂real income＂; when ＂actual income＂ is less than ＂reference income,＂ The extension of time ＂reference income＂ will adjust downwards and gradually approach ＂real income＂. Through the above discussion, we can explain the following phenomenon: As time goes by, people who overestimate their own income will gradually recognize the reality, and their evaluation of happiness (marginal utility) will gradually increase, but the happiness of each age (the total utility at the time) will gradually decline, and the happiness evaluation and happiness will gradually return to the same state as the normal state, even if there is no difference; on the contrary, underestimate the income of the person, the happiness change, as time goes by, the reality is gradually recognized, and the evaluation of happiness (the marginal utility) will gradually decline over time, but the happiness of each age (the total utility at each time) will follow the time gradually rises, and the happiness evaluation and happiness level will gradually return to the same state as usual, even if there is no difference. Therefore, this article discusses the subtle relationship between ＂time＂, ＂relative income＂ and＂ law of diminishing marginal utility＂ that have not been discussed in modern economic theory.

並列關鍵字

time ； actual income ； relative income ； Law of diminishing marginal utility

參考文獻

行政院主計處（2012）。〈家庭收支：平均每人每年可支配所得〉，縣市重要統計指標查詢系統網站，URL=http://61.60.106.82/pxweb/ Dialog/statfile9.aspS5。

林忠正（2015）。序數與基數效用理論簡史I：為何陷入兩難困境的效用理論必須重建？跨界得與失的序數邊際效用分析法（1）。中央研究院經濟所學術研討會論文。中央研究院經濟所，台北。

林忠正（2015a）。序數與基數效用理論簡史II：為何陷入兩難困境的效用理論必須重建？跨界得與失的序數邊際效用分析法（2）。中央研究院經濟所學術研討會論文。中央研究院經濟所，台北。

林忠正（2015b）。邊際效用遞減法則在序數與基數效用理論中的角色：難覓合適棲身之地的邊際效用遞減法則，跨界得與失的序數邊際效用分析法（3）。中央研究院經濟所學術研討會論文。中央研究院經濟所，台北。

林忠正（2015c）。為何Marshall需求理論必須被擺進經濟學歷史博物館？（I）跨界的得與失的序數邊際效用分析法（4）。中央研究院經濟所學術研討會論文。中央研究院經濟所，台北。