Chapter 7 examines medieval theories of the first cause of evil. Although Augustine denied that something good is the cause of evil, medieval thinkers routinely attributed to him the view that something good – the will understood as a power of the soul – causes something evil. The majority of the thinkers considered in this chapter use Aristotle’s notion of accidental causality to argue that the will can cause evil not per se – that is, not intending evil as evil – but incidentally. Nevertheless, if the will causes evil, they face the dilemma that a good will cannot cause evil at all, and an evil will cannot cause the first evil will. Medieval thinkers deal with this dilemma in different ways. For example, Bonaventure and others hold that the created will is naturally defectible, and hence not entirely unflawed, and so it can do evil. Aquinas argues that the will causing evil for the first time presupposes a momentary nonculpable deficiency, which becomes culpable at the moment of the evil choice. For Scotus, the will is so free that it can do evil even if it is unflawed. Although all these views trace evil to the will as its cause, they hold that evil is ultimately unexplainable.

Chapters 8–10 constitute Part III, entitled “Angelic Sin,” which raises the issue of how rational agents can do evil under ideal psychological conditions. Chapter 8 is about intellectualist accounts of angelic sin. Since according to these accounts, the will acts as the intellect judges best, evil acts presuppose some cognitive deficiency: either an outright error, or some occurrent nonconsideration that keeps the intellect from making the correct judgment. Thus one difficulty faced by intellectualist thinkers is how the cognitive deficiency can come about – especially since most thinkers here discussed assume that angels are infallible prior to making an evil choice. Another difficulty concerns control of the act. It is assumed that while the angels’ good or evil choice was up to them, the content of their knowledge was not up to them. Aquinas’s solution is that knowledge does not predetermine the use of that knowledge, which is up to the will. By contrast, Godfrey of Fontaines argues that the choice of the angels is caused by the cognized object; he fails to explain, however, how his theory avoids cognitive determinism.

Chapter 5 concerns the free will debate in the early fourteenth century. It thoroughly discusses the Franciscans Duns Scotus and William of Ockham, who make a sharp distinction between will and nature, that is, between a free power or cause that controls its act and one whose act is determined by external circumstances. Scotus and Ockham make the will more independent from a cognized good than previous thinkers. Using unedited texts, the chapter also presents what may well be the strongest statement of intellectualism at the time, by John of Pouilly, who builds on Godfrey of Fontaines to explain why, although our choices are moved by the cognized object, we control our choices. More briefly, the Dominicans Hervaeus Natalis and Durand of St. Pourçain are considered, whose general approach resembles Pouilly’s. As a thinker developing an intermediary theory, the chapter studies Peter Auriol, according to whom the will controls directly which judgment considered during deliberation becomes the final judgment that causes one’s choice. The dividing issue among these thinkers is, at bottom, whether the will controls its acts directly or only by means of deliberation.