This book covers the basic theories of actions that are developed by Thomas Aquinas, John Duns Scotus, and William of Ockham. These three figures are arguably the three most significant philosophers and theologians of the central period in the development of Scholastic thought. Thomas Aquinas, along with his teacher Albert the Great, was instrumental in the reception of Aristotle’sNicomachean Ethics,which had been introduced to the Latin West in the early thirteenth century. Scotus and Ockham were part of a later theological tradition that accepted the authority of Aristotle’scorpusas unproblematic. At about the same time as Aristotle’s...

Thomas Aquinas, John Duns Scotus, and William of Ockham all discuss the relationship between cognition and willing in the context of how a human act is caused. In this context, acauseis something that plays an explanatory role in the effect’s production and is in some sense a source of the effect’s existence. They use the term “cause” in a variety of ways, although each way indicates an explanation for why the effect exists in a particular manner or even at all. It is important to recognize that the medieval understanding of causality differs greatly from many accounts in...

Different views on the relation of the intellect and will to some extent affect descriptions of the role that practical reasoning plays in the production of an act, which involves disagreement over a host of problematic questions. For instance, what is the relation of a conclusion to an action? Can the conclusion of a practical syllogism be the action itself, or must the agent elicit an entirely separate act of the will for there to be an action? According to the first view, the practical reasoning has a stronger appetitive aspect, whereas in the other it is merely cognitive. A...

Thomas, Scotus, and Ockham’s views of the relationship between practical reason and the will in the production of an act are partially expressed in their descriptions of an act’s stages. They each follow a basically Aristotelian structure according to which human acts have three major components: willing the end, deliberating concerning the means, and choosing Nevertheless, they find these three components to be insufficient for fully elaborating an act’s structure. In particular, Thomas adds several stages to Aristotle’s account, in part by drawing on the language of his contemporaries, translations of Greek Fathers, and Augustine. In contrast, Scotus accepts the...

Thomas, Scotus, and Ockham all evaluate an act in terms of its object, end, and circumstances, although these three figures differ in their understanding and application of these terms. Their language has roots in ancient philosophy and the patristic tradition, and also in a particularly medieval interest in individual acts. In particular, the increasing importance of the Sacrament of Penance made it necessary for theologians to consider how to evaluate and describe such acts.¹

The distinction between the object, the circumstances, and the end has three principal sources, namely (1) the rhetorical literature about circumstances, (2) debates over whether some...

Medieval discussions of how acts are characterized are ultimately ordered to considerations about how such acts should be evaluated. Thomas, Scotus, and Ockham not only have different ways of understanding an act’s object and circumstances, but they also disagree about the different kinds of goodness and badness indicated by these features. The three kinds of goodness that belong to acts are natural goodness, moral goodness, and supernatural merit.

The distinction between natural goodness and the other two kinds of goodness is a distinction between the goodness of acts in general and the goodness that belongs to distinctively human acts. An...

No one theme or historical narrative fully accounts for all the differences between the theories of action that are developed by Thomas, Scotus, and Ockham. Any one grand theory that would account for the differences would neglect the individual genius of each thinker and the particular historical circumstances in which that thinker worked.

Many differences can be explained in terms of their individual propensities, their interests, and their reasons for writing. Scotus’s discussions often have an ad hoc character. Frequently his immediate concern seems to be only the question at hand in the particular quodlibetal discussion or lecture on the...