經濟學之化約主義—— 總體經濟學需要「消除性的個體基礎」嗎？

Reductionism in Economics—— Does Macroeconomics need eliminative Microfoundations?

姚懷捷(Huai-Jie Yao)

指導教授 ： 陳思廷 ； 王榮麟

國立清華大學/人文社會學院/哲學研究所/碩士(2014年)

摘要

本文探討經濟方法論上的教條：總體經濟學需建立在個體基礎之上。自盧卡斯提出批判後，「個體基礎」已經成為健全的總體經濟學之必要條件。基於這標準，總體模型若是沒有明確地從個體經濟理論導出，則會因使用特製的假設而遭拒絕。凱文胡佛將此種個體基礎方案稱為「消除性的個體基礎方案」

在本文中，我將質疑這個所假定的共識，並檢視其預設的哲學信念。我會先介紹支持個體基礎的理由與背景，並加以討論。我主張，當前的個體基礎皆都不盡完善，因為在處理加總問題必須依賴於不可信的簡化前提。我接著討論兩個與之相關的哲學信念：方法論個體主義與本體論個體主義。我將從馬歇爾傳統的角度指出，方法論個體主義是不必要的教條。我並探討三種版本的本體論個體主義，並逐一對其反駁。我將論證，總體經濟學無法化約至個體經濟學、總體經濟學有其自主性、以及總體經濟性質並不附隨於個體經濟性質。

我的立場大致與凱文胡佛一致，唯兩點有異。我不同意他對於附隨概念的使用，第二是我認為他引用瑟爾的社會實在的解釋將會導致本體論上的矛盾。此外，我將另從「多重均衡」與「路徑相依」的角度論證個體性質無法決定總體經濟性質。

關鍵字

消除性個體基礎方案 ； 凱文胡佛 ； 盧卡斯批判 ； 方法論個體主義 ； 本體論個體主義 ； 附隨 ； 多重均衡 ； 路徑相依

並列摘要

This paper considers the doctrine that macroeconomics must be based on microfoundations. Nowadays, microfoundations has become the sine qua non of sound macroeconomics after the Lucas critique. Due to this criterion, macroeconomic models that are not explicitly derived from microeconomic principles are rejected on account of using "ad hoc" assumptions. Kevin Hoover calls this version of microfoundations "eliminative microfoundations".

In this paper, I will challenge this presumed consensus and discuss its underlying philosophical beliefs. The rationale of microfoundations will be introduced and discussed. I conclude that the dominant microfoundations are unsatisfactory because their aggregation procedures rely heavily on unbelievable assumptions. I then discuss the two relevant philosophical beliefs: methodological individualism and ontological individualism. I argue that methodological individualism is not necessary from the perspective of Marshallian tradition. Next, I discuss three versions of ontological individualism and refute them respectively. I argue that (1) Macroecnomics can not be reduced to Microeconomics and that (2) Macroeconomics has its own autonomy and that (3) macroeconomic properties do not supervene on microeconomic properties.

Basically, I agree with what Kevin Hoover said except two things. I argue that his use of the notion "supervenience" is inappropriate, and that his appeal to John Searle' ontological account can lead to a contradiction. Finally, applying the concept of "multiple equilibria" and "path dependence", I argue that macroeconomic properties are not fully determined by microeconomic properties.

並列關鍵字

eliminative microfoundations ； Kevin Hoover ； Lucas Critique, methodological individualism, ontological individualism, supervenience, multiple equilibria, path dependence ； methodological individualism ； ontological individualism, ； supervenience, ； multiple equilibria, ； path dependence

參考文獻

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Epstein, B. (2008). Economics and Nonsupervenience. Manuscript, Tufts University.

Epstein, B. (2009). Ontological individualism reconsidered. Synthese, 166(1), 187-213.