Cajetan Cuddy looks at conscience through the thought of St. Thomas Aquinas. Conscience is an act of ordering knowledge – some universal and some particular – to an act, whether past, present, or future. Conscience directs future acts, and regarding past acts, can accuse or excuse. Aquinas compares conscience and synderesis – the person’s inclination shaping her understanding. Synderesis turns human nature to good and objects to evil. It gives awareness of the principles of morality to be applied to actions. Synderesis concerns knowing the principles applicable to all actions, and conscience applies knowledge to a specific act. Thus, conscience comes from synderesis. But conscience has limits and can be wrong and need correction. A mistaken conscience does not stop a person’s orientation to the truth, and error can be fixed. Conscience and God’s law both bind for Aquinas, not because conscience is perfect or reason is independent of the law, but because conscience mediates God’s norms to humans doing a particular action. This is done through the application of synderesis, which is always ordered to moral truth, meaning to God.

Alexis Torrance considers early Church Fathers’ many treatments of the origins and roles of conscience in patristic literature. Contemporary commentators are especially prone to speak of conscience to affirm private judgments about personal feelings. Early Church Fathers, however, stressed that conscience is a communal gift presupposing shared convictions. They also stressed that conscience may become impaired under a variety of influences. The idea of conscience existed in Greek and Roman culture. Christians’ reflections, especially St. Paul, were crucial to the deliberations of Church Fathers. New Testament letters speak of conscience as a human faculty. Though not God’s voice, conscience does bring God’s voice to bear in our lives. Christian innovation connected conscience with the idea of a divine law, and some patristic authors identify conscience with a natural law. Human knowledge of right and wrong will be clouded by sin, thus conscience needs cleansing, by baptism, by following the commandments, and by continual examination of conscience and confession. It continually requires the grace of the Holy Spirit to govern one’s moral action in a way that might lead to God.