當今學界對奧古斯丁《答辛普里西安努》I.2有分裂派和連續派兩種解讀方式。本文從這一爭議出發，指出奧古斯丁的自由意志學說的貢獻在於構建了與自我具有緊密關聯的決斷能力。首先，本文以奧古斯丁意志思想變化為中心，指出奧古斯丁在「恩典」、「原罪」等方面所展現出來的新的思想特點，由此指出奧古斯丁對意志權能認識的變化，即人無法進行善惡之間的選擇；其次，為了回應斷裂派，本文將澄清奧古斯丁自由意志學說的學說，並從意志的自明性，「意願」和「自由決斷」的區分及自由決斷與自由選擇之間的關係出發來展開論述。我們看到奧古斯丁所主張的自由意志是一種不同於現代人所理解的個人的自由選擇，更彰顯出人的道德主體性及責任意識。

There are two interpretations of Augustine's Ad Simplicianum I.2: the separate reading and the continuous reading. By unpacking the controversy between these opposite approaches, this article argues that a crucial contribution of Augustine's theory of free will lies in establishing a faculty of decision that is related to self. According to Augustine, freedom does not lie in alternative choices, but in the decision of the will itself. To begin with, this article examines the novel developments of the theory of grace and original sin and show that Augustine has a unique understanding of the power of the will, namely, that a human cannot choose between good and evil. As a response to the separate reading, this article then clarifies Augustine's conception of free will from three aspects: firstly, the self-evidence of the will, then the distinction between will (uoluntas) and free decision (liberum arbitrium), and lastly, the relationship between free choice and free decision. Finally, this article analyzes the role of the will in Augustine's discussions on sin and grace in Ad Simplicianum I.2, and concludes that Augustine's theory of free will differs from the modern understanding in that it emphasizes both moral responsibility and autonomy.