Human Action in Thomas Aquinas, John Duns Scotus, and William of Ockham by Thomas M. Osborne, Jr. (review)

The present book promotes Thomas Aquinas, John Duns Scotus, and William of Ockham as the most influential of scholastic thinkers, and it sets forth their respective theories of action. These three generally Aristotelian theorists worked within a “new moral theology that placed an emphasis on the description and evaluation of particular acts” in large part because “the increasing importance of the Sacrament of Penance made it necessary for theologians to consider how to evaluate and describe such acts” (XIII, 149). The volume is both exegetical and historiographical; it provides a highly technical, textually detailed assessment of the thinkers’ respective philosophies of action while also engaging longstanding historical narratives that have attempted to incorporate the distinctive approaches of these thinkers. It is no longer plausible to hold that Aquinas’s Summa theologiae is the pinnacle of scholastic thought, with Scotus and Ockham representing successive stages of degeneration.

Osborne seeks to examine the moral psychology of Aquinas, Scotus, and Ockham in comparison with each other from the point of view of medieval issues, rather than in light of the interests or tastes of contemporary philosophers. Readers accustomed to valuing medieval philosophical and theological works simply in light of the concerns of present-day philosophizing will be challenged, but, in the notes, Osborne engages helpfully with contemporary scholarship on medieval texts. The general order for discussing topics is patterned after Aquinas’s account of human action in Summa theologiae, Prima secundae, questions 6–21. While equal treatment is given to Aquinas, Scotus, and Ockham, the presentation appears to favor Aquinas as the touchstone against which the other two are compared. Such an approach is perhaps unavoidable to some extent, as Aquinas wrote considerably more on the topics covered in the book than did Scotus and Ockham, and Aquinas did so with greater systematization.

The first chapter (“Causes of the Act”) considers how both the will of the agent and the known object are causes of the moral act for Aquinas, Scotus, and Ockham. The chapter emphasizes points of agreement and disagreement concerning types of causality and various understandings of the role of the intellect in the moral act. Chapter 2 (“Practical Reason”) considers practical syllogisms and notes how present-day disagreements about how to interpret Aristotle’s remarks about the practical syllogism can be read anew in light of the divergent interpretations of the three medieval Aristotelians on practical reasoning. The third chapter (“Stages of the Act”) further considers modifications and amplifications of Aristotle’s doctrines. How many stages are there to a human act? Although all three thinkers follow an account largely consistent with Nicomachean Ethics III, 1–4, Osborne sets forth how each thinker modifies the Aristotelian inheritance: “By any plausible account, Thomas describes more than eight stages and he may give as many as twelve. In contrast, Ockham enumerates only six, and Scotus describes five or fewer” (145). Chapter 4 (“Evaluation and Specification of the Act”) considers Thomas, Scotus, and Ockham’s individual accounts of acts in terms of circumstances, object, and end. The chapter begins with a historical overview of the traditional septem circumstantiae of the rhetorical tradition, and Osborne notes that it “corresponds in large part to Aristotle’s description in the Nicomachean Ethics of what an agent must know about an act for the act to be voluntary” (150). Recent philological work confirms Osborne’s insightful intuition (see Michael C. Sloan, “Aristotle’s Nicomachean Ethics as the Original Locus for the Septem Circumstantiae,” Classical Philology 105 [2010]: 236–51). Chapter 5 (“Indifferent, Good, and Meritorious Acts”) considers the respective views of the three medieval thinkers on issues of merit. The volume concludes by identifying themes found within Aquinas, Scotus, and Ockham. While Osborne notes that the respective philosophies of action defended by Aquinas, Scotus, and Ockham resist any successful explanation in terms of a single principle, he highlights a triad of common themes found...