Christian Moral Theology

Thomas Aquinas gave Christian moral theology its lasting shape in the Summa Theologiae's Prima Secundae and Secunda Secundae, written between 1265 and 1274. Rather than listing rules, he organized the whole of moral life around the virtues: the four cardinal virtues of prudence, justice, fortitude and temperance, received from Aristotle, joined to the three theological virtues of faith, hope and charity, and grounded in natural law, the rational creature's participation in the eternal law. Human acts, sin and grace all find their place within that architecture rather than standing as separate topics.

After Trent, the discipline drifted toward the confessional. Manuals of moral theology multiplied through the sixteenth to nineteenth centuries as practical guides for confessors, organized case by case around what counted as sin and how gravely, a method called casuistry. Critics argued the manuals had reduced Aquinas's virtue centred vision to a legal calculus for absolving penitents.

The Second Vatican Council's decree on priestly formation, Optatam Totius, called for moral theology to be renewed by closer contact with Scripture and a fuller account of the Christian vocation to charity, rather than remaining a manual of case law. Pope John Paul II's 1993 encyclical Veritatis Splendor carried that renewal furthest, defending moral absolutes against proportionalist readings of natural law and restating virtue as the discipline's proper centre.

Moral theology asks what is right and why. Pastoral theology, the neighbouring seminary discipline, asks how a minister applies that answer to a particular soul, a distinction the manuals sometimes blurred and Vatican II's reform tried to restore.

The confessional manuals that followed Aquinas were consumed by a controversy for over a century. Probabilism, the position that a confessor may follow any solidly probable opinion about what the law requires even when a stricter opinion is also probable, became standard practice among many Jesuit moral theologians by the seventeenth century, intended to avoid binding penitents to the harshest available reading of a doubtful case.

Jansenist writers attacked the practice as moral laxism dressed up in scholastic language, most famously in Blaise Pascal's Provincial Letters of 1656 and 1657, which mocked probabilist casuistry as a system for excusing almost anything a confessor wished to excuse. Rome eventually intervened against the excesses on both sides: a series of condemnations targeted lax propositions associated with probabilism, while Jansenism's own rigorist alternative, which tended toward withholding absolution and communion until a penitent's contrition was judged sufficiently severe, was condemned as well.

Alphonsus Liguori, an eighteenth century Neapolitan bishop, proposed the resolution that eventually won out, equiprobabilism, holding that a penitent may follow a probable opinion favoring liberty only when it is at least as solidly grounded as the opinion favoring the law, a narrower door than unrestricted probabilism and a wider one than Jansenist rigorism. He was later declared a Doctor of the Church and patron of confessors and moral theologians, and his cautious middle path, not either extreme, became the working standard of Catholic moral theology in the centuries before the Vatican II reform.