 Augustine’s thinking about free will (liberum arbitrium or liberum voluntatis arbitrium) undergoes some development during his career. In the 390s, opposing the dualistic fatalism of the Manicheans, he uses the cogito-like argument (see  5.1 Skepticism and Certainty)  to demonstrate that we are responsible for our volitions because we are as certain that we will as we are certain that we exist and think (De duabus animabus 13; De libero arbitrio 3.3; Confessiones 7.5; S. Harrison 1999). A contemporaneous definition of will as a movement of soul toward some object of desire emphasizes the absence of external constraint, and the ensuing definition of sin as an unjust volition (see above) seems to endorse the principle of alternative possibilities (De duabus animabus 14–15). In De libero arbitrio, free will appears as the condition of possibility of moral goodness and hence as a great good itself; but as it is not an absolute good (which is God alone) but only an intermediate one, it is liable to misuse and, hence, also the source of moral evil (De libero arbitrio 2.47–53). In his early exegesis of Paul’s chapter on divine election (Romans 9), Augustine is keen to establish that Paul did not abolish free will (Expositio quarundam propositionum ex epistula apostoli ad Romanos 13–18). With all this, Augustine is basically in harmony with the traditional view of early Christian theology and exegesis, which is still adopted in the 420s by Julian of Aeclanum when he blames Augustine for having fallen back into Manichean fatalism and quotes his early definitions against him (Julian, Ad Florum, in Contra Iulianum opus imperfectum 1.44–47). Things change with Ad Simplicianum 1.2 and the Confessiones. By c. 400 CE, Augustine had come to the conclusion that our ability to make choices was seriously impaired by the fallen condition of humankind and that it made little sense to talk about free will without reference to grace. The optimistic-sounding claim in the first book of De libero arbitrio (1.25–26; 29) that it is in our power to be good as soon as we choose to be good because “nothing is as completely in our will as will itself” was probably never the whole story; already in book 3 of the same work Augustine says that the cognitive and motivational deficiencies caused by Adam’s sin (“ignorance and difficulty”, ib. 3.52; S. Harrison 2006: 112–130) seriously compromise our natural ability to choose the good, and in his later, especially anti-Pelagian work he radicalizes this to the idea that original sin makes us unable to completely subdue our sinful volitions as long as we live, so that we live in a permanent state of “akrasia” or weakness of will (De natura et gratia 61–67; De civitate dei 19.4; De nuptiis et concupiscentia 1.35). But he never questions the principle that we have been created with the natural ability to freely and voluntarily choose the good, nor does he ever deny the applicability of the cogito argument to the will (cf. De civitate dei 5.10) or doubt that our volitions are imputable to us. What grace does is to restore our natural freedom; it does not compel us to act against our will. What this means is best illustrated by the narrative of Confessiones 8 (for particularly lucid interpretations, see Wetzel 1992: 126–138; J. Müller 2009: 323–335). Immediately before his conversion Augustine suffers from a “divided will”, feeling torn apart between the will to lead an ascetic Christian life and the will to continue his previous, sexually active life. Though he identifies with the former, better will rather than with the latter that actually torments him, he is unable to opt for it because of his bad habits, which he once acquired voluntarily but which have by now transformed into a kind of addictive necessity (ib. 8.10–12). Earlier philosophical traditions would have interpreted this “akratic” state as a conflict of reason and desire, and Manichean dualism would have attributed Augustine’s bad will to an evil substance present in but foreign to the soul, but Augustine insists that both wills were indeed his own. Using medical metaphors reminiscent of Hellenistic moral philosophy, he argues that his will lacked the power of free choice because the disease of being divided between conflicting volitions had weakened it (ib. 8.19; 21). His ability to choose is only restored when, in the garden scene at the end of the book, his will is reintegrated and healed by God’s call, which immediately frees him to opt for the ascetic life (ib. 8.29–30). Before, when he had just continued his habitual way of life, this had been a non-choice rather than a choice, even though, as Augustine insists, he had done so voluntarily. In substance, this remained his line of defense when, in the Pelagian controversy, he was confronted with the charge that his doctrine of grace abolished free will (De spiritu et littera 52–60; cf. De correptione et gratia 6). While the Pelagians thought that the principle of alternative possibilities was indispensable for human responsibility and divine justice, Augustine accepts that principle only for the first humans in paradise (Contra Iulianum opus imperfectum 1.47; 5.28; 5.40–42 etc.). In a way, by choosing wrongly Adam and Eve have abandoned free will both for themselves and for all humankind. Original sin transformed our initial ability not to sin into an inability not to sin; grace can restore ability not to sin in this life and will transform it into inability to sin in the next (De civitate dei 22.30; De correptione et gratia 33).