From the dawn of the Middle Ages to their end, moral theorists struggled to explain what makes a person good by human standards, what it takes to merit happiness in the afterlife, and what, if anything, the two have to do with each other. Some inveighed against the worldly ethics of ancient philosophers; others praised the ancients for important moral insights. Yet every leading medieval thinker worked to develop an account of the moral life far more comprehensive than most professors of philosophical ethics or moral theology today would attempt. The idea that a serious theologian could dismiss classical ethics as unworthy of study and debate was no more acceptable than the idea that a serious philosopher could dismiss questions about the immortality of the soul and the nature of God as irrelevant to moral life in human society.

I shall begin by sketching Augustine’s pioneering work in ethics, along with some of the puzzles it creates. After a look at respectful but significant revisions of Augustine by Anselm of Canterbury, I turn to the brave new world of universities, where the pagan Aristotle soon emerged as an authority to be reckoned with. Beginning in the mid-thirteenth century, efforts to weave together his insights with Augustine’s became at once highly complex and the occasion for passionate academic dispute.