亞里士多德批評柏拉圖對靈魂部分的劃分,他認為靈魂的各部分在空間上不可分,僅在定義上可分。"靈魂在定義上可分"指的是各個部分的定義不包含彼此,因此,靈魂僅有三個真正的部分:營養、感知和理性。然而,靈魂的多部分如何構成統一體對于亞里士多德是一個迫切的問題,因為任何一個生物體的靈魂都是單一的形式。《論靈魂》第二卷第三章解釋說靈魂的統一性是由于"低級部分潛在地存在于高級部分之中"。本文指出這個解釋是不清晰的,靈魂的統一性辯護另有兩種可能:一種是在亞里士多德之后的傳統中發展起來的"虛擬潛在性"概念,另一種是亞里士多德將生命活動作為整體目的的論證。

Aristotle divides the soul into different parts according to various life functions. A given part of the soul is not spatially separate from other parts but rather only definitionally,meaning that the definition of each part neither refers to nor is referred to by other parts. Therefore,the soul divides into three parts: the nutritive,the perceptive,and the rational. However,given that the soul of any living being is a single form,how the parts of soul constitute a unity remains a crucial problem for Aristotle. De Anima III. 2 claims that the unity of the soul is achieved because the lower part exists potentially in the higher part,e. g.,the nutritive part exists potentially in the perceptive part. This paper argues that this explanation is too brief to make sense,and that there are two alternatives for defending Aristotle’s notion of the unity of the soul: one is the concept of virtual potentiality developed in medieval philosophy,and the other is Aristotle’s own argument for treating the living creature as a single end,and as a whole.