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

The editors at The Catholic University of America Press chose the cover art for this book with real insight. A painting (circa 1500) shows several dozen clearly rendered men and women engaged in the business of living. Among them are a dentist pulling teeth, a nun praying while another gathers hay, two men in a brawl, and a lady reading, while Christ looks down from heaven upon them all. It is this collection of actions—the good, the bad, and the possibly indifferent—that Thomas Aquinas, Scotus, and Ockham, each in his own way, worked to systematize. These three diverse efforts at systematization are the subject of Osborne's book on human action. Just as the painter was careful to draw each small character in detail, so too Osborne is careful with all the relevant details of the five areas of action theory he chooses to elaborate: the causes of human action, the role of practical reasoning in choice, the stages of action, the specification of moral action, and the supernatural and moral worth of action.

The first (and longest) chapter, on the causes of human acts, reflects upon how the three figures differ regarding the root of freedom, whether the known object is the cause of the human act, and the relationship between freedom and the good. Aquinas sees reason as the root of freedom, while Scotus and Ockham do not. Aquinas sees the known object as a final cause, while for Scotus and Ockham it is a partial efficient cause. The chapter ends with a short disquisition on the inadequacy of characterizing the contrast as simply that between intellectualism and voluntarism.

The second chapter, on practical reason and the practical syllogism, is largely a presentation of three elaborations of Aristotle's account of the practical syllogism in the Nicomachean Ethics. As Osborne notes, Aristotle's account gave rise to a number of questions, such as whether the conclusion of such reasoning was the action itself, and whether the premises for such reasoning were of a different character than theoretical premises. The chapter presents a number of rather technical attempts to resolve these and other questions. Osborne is to be praised for pointing out in medieval action theory the role of Aristotle's ideas and the overall importance of prudence and practical reasoning. At the same time, though, this chapter is less interesting than the previous one, since it is more difficult to see how any of these theories leads to any significant difference for humans who are thinking about their own actions. Different theories about the root of freedom will lead to very different overall views of human life. But is distinguishing—or not distinguishing—different degrees of practical reason going to have a wider impact? Osborne himself is largely interested in how these theories about practical reasoning are the result of the causal theories he discussed in the first chapter: he identifies a trend of separating nature from will and an increasing emphasis on the will's activity.

The third chapter, on the stages of the act, involves a similar mass of detail. Osborne threads his way through the multitudinous stages of the act in Aquinas (including remarks on the historical background of stages such as "consent") and the much simpler versions provided by Scotus and Ockham. As with the previous chapter, to Osborne the significance of this complex maze lies in the fact that it reflects the causal theories elaborated in chapter 1: Scotus and Ockham do not incorporate natural inclination into their understanding of the will's stages, and for them intellect and will act in separate stages, while for Aquinas they cannot be separated.

Chapter 4, on the evaluation and specification of the human act, presents a topic that is perhaps...