Did Augustine of Hippo Lose his Debate with Fortunatus?

In 392, Augustine of Hippo engaged in a face-to-face debate with Fortunatus, a Manichaean priest of Hippo. According to the traditional view, Augustine undoubtedly won this debate, as was understood by Augustine himself and the audience. Since the mid-20th century, however, a new trend of interpretation represented by Jason David BeDuhn has sought to argue that, in this two-day debate Augustine did not demolish Fortunatus' argument, but accepted his opponent's main ideas, which suggests that Augustine essentially lost the debate. By comparing this debate with De libero arbitrio and other early works, this article demonstrates that Augustine did not lose the debate and that the shift of his argument was a transition from a metaphysical argument on the first day to a historical-theological one on the second day, which revealed some of the profound differences between the Catholic and Manichaean doctrines.