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

Thomas Osborne's Human Action in Thomas Aquinas, John Duns Scotus, & William of Ockham provides a helpful comparative analysis of three key medieval thinkers with respect to their distinct accounts of human action or theories of "moral psychology" (xvi). These thinkers, Osborne states, "are arguably the three most significant philosophers and theologians of the central period in the development of Scholastic thought" (xiii). His work is written in an accessible style that renders it useful not only as a resource for specialist researchers in the medieval era but also as a supplemental text for course instruction at the graduate level. While the exact focus and content of this study is unique, it is comparable in approach to other recent volumes in medieval ethics and moral theology such as M. V. Dougherty's Moral Dilemmas in Medieval Thought: From Gratian to Aquinas (2013), or to the comparative medieval studies of Marilyn McCord Adams, Richard Cross, or Russell L. Friedman.

Osborne states that his study aims to provide an overview of the issues with which medieval moral psychology grappled and that this, in turn, will serve to illuminate key philosophical questions in ethics, as well as to provide historical background for understanding Reformation and early modern thought (xvi). While Osborne states that his primary goal is to provide a systematic overview of the three thinkers under consideration, his study also illustrates a contextual historical understanding of the authors in question. For example, at times, he provides occasional contextual references to other important medieval ethicists such as Anselm of Canterbury, Peter Abelard, Peter Lombard, and Albert the Great. Osborne is explicitly conscious of the methodological need to avoid conforming the authors under consideration to a superficial historical narrative in which Scotus is construed as reacting to Aquinas, and Ockham in turn to Scotus (see 222–23, where Osborne briefly critiques two common historio-graphical trends). On this point, Osborne recognizes that Aquinas in the era prior to his canonization did not have as significant an intellectual import for Franciscan thinkers as contemporary scholars might expect (xix). Overall, Osborne indicates that his comparative studies should serve to provide his reader both with basic familiarity with the moral psychology of each thinker and with a cognizance of the doctrinal currents that proved to be influential upon subsequent Western thought (xxv). In this respect, Osborne points to three main themes that he indicates establish a reliable historical narrative concerning the doctrinal developments in fundamental ethics from Aquinas to Ockham: "(1) a developing separation between nature and will, (2) an increased emphasis on the will's activity, and (3) a changing view of mental causation" with respect to elicited exterior acts (xxiv–xxv, cf. 227). These themes collectively provide a helpful orientation for continued study of these thinkers, a framework that other scholars will benefit from exploring and evaluating.

Osborne's work is organized into five chapters enveloped by an introduction and a conclusion. Each of the five chapters is focused on a particular ethical topic, such as the causes of a moral act (viz., an agent's intellect and will), the stages of a moral act, or the specification of a moral act. Regarding the structure of the book, Osborne states that it "develops thematically" (xxii). The topical arrangement of the study is intended generally to follow the ordo doctrinae found in questions 6–21 of the prima secundae of Aquinas's Summa theologiae, which Osborne maintains is the most complete and systematic treatment of moral psychology found among the works of the three thinkers under consideration (xvi). Each of Osborne's chapters is further divided into four parts. This schema for the most part follows a common pattern of first expositing Aquinas's position on the ethical topic at hand and then the positions of Scotus and Ockham and closing with a synopsis that compares and contrasts the main positions of...