跨期消費理論與蛛網理論的重新審視： 林忠正「個體選擇的交換理論」的動態延伸

The Reconsiderations of Intertemporal Consumption Theory and Cobweb Theory: Dynamic Extensions of Chung-Cheng Lin's “the Exchange Theory of Individual Choice”

陳政弘(Cheng-Hung Chen)

指導教授 ： 林忠正

共同指導教授 ： 宋玉生(Yusen Sung)

國立臺灣大學/社會科學院/經濟學研究所/博士(2015年)

https://doi.org/10.6342/NTU.2015.01623

摘要

經濟學現有的序數效用(ordinal utility)與基數效用(cardinal utility)兩種主要效用理論，都有其理論上的侷限性，因為序數效用理論不容許常識性的邊際效用遞減等概念，基數效用是效用概念與長度概念一樣是可衡量的。林忠正(2015a，2015b)發展出一套「個體選擇的交換理論與序數的邊際效用分析法」，可以在效用是序數的概念(效用的數值只有大小次序有意義)之下同時能挽救回邊際效用遞減等概念。由於效用理論是經濟學的基礎理論，出現新的效用理論意味著可能會帶來一整套截然不同的經濟理論。本論文基於這個新的分析工具，進行兩個延伸性的工作。
其一是將林忠正現有的「個體選擇的交換理論與序數的邊際效用分析法」的基本模型(靜態模型)，透過影響可支配財富的管道，以描繪消費的動態歷程並藉此建構分析動態消費行為的基本架構。據此我們可以得到起始的可支配財富、所得、商品的價格以及利率如何影響往後各期的可支配財富以及消費，且能輕易地延伸至消費成癮等概念。與生命週期假說相比，我們的新分析架構除了保有林忠正的新效用理論的優點，容易納入許多行為經濟學所討論的決策心理過程，同時在決策者的理性能力要求較低，可以合理解釋破產以及自制力的問題，也能分析所得來源影響各期消費數額的現象。
其二則是提出一個新的蛛網理論的分析與詮釋方法，這將說明我們的新架構不但可以描述決策者的行為動態，也能夠分析供需雙方價量的互動，成為新的市場動態分析的叩門磚。若與舊有理論相比，我們的新分析架構除了保有「個體選擇的交換理論」的優點，同時在決策者的理性能力要求較低之下，可以避免模型修正的方針朝向「理性預期」這個看得到卻走不到的海市蜃樓。最後，我們也展示了商品價格更一般化的設定形式，說明市場結清均衡未必是此課題必要的條件，而是一個特例。

關鍵字

效用理論 ； 個體選擇的交換理論 ； 序數的邊際效用分析法 ； 跨期消費理論 ； 生命週期假說 ； 蛛網理論

並列摘要

There are two main utility theories in Economics: ordinal utility and cardinal utility. Either of theories, however, is not trouble-free. The troubles of the ordinal theory are inconsistent with some commonsense, for example, the principle of diminishing marginal utility and the complementarity defined by the cross-derivatives of utility. The problem of the cardinal utility is that utility is measurable. Chung-Cheng Lin (2015a, 2015b) proposes a new individual decision theory, called the exchange theory of consumer choices and the ordinal marginal utility approach, retains the merits of both main existing utility theories, and immunes to their troubles. Since the utility theory is the foundation of modern economics, the emergence of a new utility theory implies the landscapes of economic theories may change radically. In this dissertation, we try to extend the new approach to some interesting issues.
First, we use the channel of the disposal wealth to describe the dynamic process of consumption and construct the basic dynamic analytical framework of intertemporal choices. So we get how the consumptions changes as the initial wealth, income, price and interest rate changes, moreover, we can easily extend this work to the concept of addiction. Compare with the life cycle hypothesis, our new framework not only retains the advantages of the exchange theory of consumer choices, but also contains the mental process of decision making. Our approach also requires less rational ability, such that we can easily to explain bankrupt, self-control and how the income path affects the consumption path.
Second, we try to reconstruct the cobweb theory, this shows that our approach could be the new method to analyze the interactions between demander and supplier. Compare with the traditional one, our new framework retains the advantages of the exchange theory of consumer choices and does not need to increase the ability of decision maker to the rational expectation. Finally, we also show that market price could be set more flexible, the market cleaning equilibrium is just a special case in our model.

並列關鍵字

utility theory ； exchange theory of consumer choices ； ordinal marginal utility approach ； intertemporal consumption theory ； life cycle hypothesis ； cobweb theory

參考文獻

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Becker, G. S., & Murphy, K. M. (1988). A theory of rational addiction. The journal of political economy, 675-700.

Carlson, J. A. (1968). An invariably stable cobweb model. The Review of Economic Studies, 360-362.

Chiang, A. C. (1984). Fundamental methods of mathematical economics. McCraw-Hill.