《理想國》中的功能論證與對反原則

Abstract

柏拉圖在《理想國》中指出正義牽涉的議題範圍廣大，包括政治、倫理、宗教、教育及社會等面向。為了含括這些面向，柏拉圖以城邦與靈魂的平行類比作為前提，描繪城邦與靈魂的內在結構：相似的三個階級對應三個部分。這三個階級與部分能得到劃分是依著正義原則，即每個部分不逾越其本分地從事一項工作。進一步而言，城邦的三階級或靈魂的三部分若要能達到和諧不對立，需遵守功能論證的精神，即每個部分從事的工作，是合乎其本性的良好發揮的工作；此外唯有本性的良好發揮才能展現好德性。在精確展現功能論證的全貌之前，柏拉圖設計了第一階段教育。對教育內容的論述使對話者擁有深入了解功能論證的適當基礎。 此後隨著論述深度的增加，柏拉圖指出正義之外的三種德性，即智慧、勇氣、與節制。這些德性都必須在合乎城邦與靈魂的平行類比之前提與功能論證的精神之下，才能得到適切的理解。關於靈魂的三分，柏拉圖在第四卷使用對反原則，即對反的事物會發生在不同的部分，進行論述。在本文的核心討論中將指出，對反原則其實是以功能論證作為核心的結構的外皮，而功能論證又與正義原則是一體兩面；城邦與靈魂在這個結構下得到完整的理解。儘管對反原則是功能論證的外皮，但它的重要性在卷八、九描述墮落城邦與靈魂時顯現。亦即，在將城邦與靈魂依高下排序時，呈現了它們的改進空間。 以城邦與靈魂的平行類比作為前提，功能論證與對反原則在《理想國》中的效用是：前者指出了和諧城邦與靈魂的完整面貌，後者指引出通往這個和諧的道路。

In the Republic, Plato points out that justice is related to a variety of issues, including politics, morality, religion, education, and society etc. In order to touch upon these aspects, by using the analogy of the city and the soul as premise, he describes the inner structures of the city and the soul which consist of three classes and three parts respectively and are similar to each other. The three classes, or three parts, can be divided by the principle of justice, and each part does its own duty without being meddlesome. Furthermore, to make the three classes in the city or the three parts in the soul harmonious without conflicts, each one should devote itself to the activity corresponding to its nature, which is the spirit of the ergon argument. The soul could present proper virtues only when the reason functions properly and the other two parts function in accordance with the rational guide and order. Before the picture of the ergon argument is fully drawn, Plato describes the first stage of the education, which gives the interlocutors an adequate ground for understanding the detail of it. As the argument proceeds, Plato points out that in addition to justice, there are three more virtues: wisdom, courage, and temperance. These virtues could be understood properly only under the premise of the city-soul analogy and the spirit of the ergon argument. When it comes to the tripartition of the soul, Plato discusses it in Book IV by virtue of the principle of opposites, namely, the opposite things only emerge from different parts. The purpose of this thesis is to demonstrate that the principle of opposites is the surface of a structure taking the ergon argument as nucleus, and that the surface and the nucleus are two aspects of one and the same thing. The details of the city and the soul is demonstrated under this structure. Although the principle of opposites is a surface, the importance of it is highlighted when Plato in Book VIII and IX describes the corrupted cities and souls. Though Plato’s discussion of them in the order of their moral decline, yet the possibility of their improvements are displayed. Taking the city-soul analogy as a premise, the effect of the Ergon Argument and the Principle of Opposites is showed: The former unfolds a complete picture of the harmonious city and soul, the latter shows the way of achieving it.