This Element provides an account of Thomas Aquinas's moral philosophy that emphasizes the intrinsic connection between happiness and the human good, human virtue, and the precepts of practical reason. Human beings by nature have an end to which they are directed and concerning which they do not deliberate, namely happiness. Humans achieve this end by performing good human acts, which are produced by the intellect and the will, and perfected by the relevant virtues. These virtuous acts require that the agent grasps the relevant moral principles and uses them in particular cases.

Thomas Aquinas produced a voluminous body of work on moral theory, and much of that work is on virtue, particularly the status and value of the virtues as principles of virtuous acts, and the way in which a moral life can be organized around them schematically. Thomas Osborne presents Aquinas's account of virtue in its historical, philosophical and theological contexts, to show the reader what Aquinas himself wished to teach about virtue. His discussion makes the complexities of Aquinas's moral thought accessible to readers despite the differences between Thomas's texts themselves, and the distance between our background assumptions and his. The book will be valuable for scholars and students in ethics, medieval philosophy, and theology.

This book sets out a thematic presentation of human action, especially as it relates to morality, in the three most significant figures in Medieval Scholastic thought: Thomas Aquinas, John Duns Scotus, and William of Ockham. Thomas, along with his teacher Albert the Great, was instrumental in the medieval reception of the action theory of Aristotle's Nicomachean Ethics. Scotus and Ockham were part of a later Franciscan theological tradition. Thomas, Scotus, and Ockham worked in the context of a new moral theology that focused on the description and evaluation of human acts. Organized thematically, discussing the causes of human action, the role of practical reasoning, the stages of action, the specification of moral action, and an act's supernatural and natural worth. Each chapter compares the three main figures on the same set of issues. The book shows that although the different philosophies of action cannot be explained in terms of any one major difference or principle, there are some common themes that deserve attention. The most notable themes are 1) a developing separation between nature and the will, 2) an increased emphasis on the will's activity, and 3) a changing view of mental causation. The book is important for those who are interested in medieval philosophy, the philosophy of action, and the intellectual background to Reformation and early modern thought.