多瑪斯跟隨亞里斯多德對「正義」╱「義德」的看法，並接受羅馬法學家的見解，界說「正義」╱「義德」為：「一種將每個人的權利歸諸於每個人身上之恆常而不變的意志的習慣。」本文則進一步探討多瑪斯的正義╱義德之組成部分。按照多瑪斯，他將正義╱義德之組成部分從三方面著眼：第一，正義╱義德組成之「主要的部分」（the subject parts），也即是「正義的種類」（the species of justice），於此指出「分配正義」與「交換正義」兩種正義；第二，「擬似絕對必要的部分」（the quasi-integral parts），也就是「行善」和「減低惡」（「惡」指「對反的惡行」）；第三，「擬似潛能的部分」（the quasi-potential parts），就是與正義╱義德相關聯的德行，多瑪斯歸納出九項。

　　　　　Aquinas followed Aristotle's views about "justice" and accepted the idea of Romanists, defining "justice" as: justice is a habit whereby a man renders to each one his due/right by a constant and perpetual will. This paper is intended to further explore the constituents of Aquinas's "justice." Aquinas saw the constituents of justice in three different lights: first, the subject parts of the constitution of justice, that is, the species of justice, here pointing to distributive justice and commutative justice; second, the quasi-integral parts, that is, doing good and reducing vice (as opposed to good); and third, the quasi-potential parts, which are the nine virtues associated with justice that Aquinas induced.