許多研究柏拉圖學說的學者都認為柏拉圖的著作 Phaidon 主要的核心討論是有關靈魂不朽的問題，本篇論文與以往的學者的觀點不一樣，本文認為柏拉圖在Phaidon裡所要討論的是相論的問題，而靈魂不朽只是柏拉圖的假設法裡的一個階梯，透過這個階梯柏拉圖要論證相的世界的存在。本篇論文是以柏拉圖的 Phaidon 為核心來探討柏拉圖的假設與相的學說的關係，並在這個基礎上來論證柏拉圖的相的學說是一套內在的理論。

Some scholars who enquire into the doctrine of Plato hold that the main discussion of Plato’s
Phaidon concerns the immortality of soul. The view of this paper, which argues that Plato’s purpose is
to investigate the theory of Ideas in the Phaidon, differs from the perspective of other scholars. The
immortality of soul is a footstep in Plato’s hypothesis, through which Plato shows the world of Ideas.
This paper focuses on Plato’s Phaidon to explore the relation between the hypothesis and the doctrine
of Ideas, and in such foundation to show that the doctrine of Plato’s Ideas is the theory of Immanence
of Ideas.