With the new millennium, papal power sought to restore Christian rule in the Holy Land through a series of eight crusades, but these campaigns were military and political failures, especially at the expense of the Papacy. However, they did succeed in opening the way for the scholarship of the Islamic world to enter western European intellectual life. With the founding of universities, new scholarship slowly emerged. The pioneering teachings of Pierre Abélard, Roger Bacon, and Albertus Magnus led to a revival of interest in the ancient writers with their emphasis on rational thought to secure human knowledge. This movement, called Scholasticism, reached its pinnacle with the writings of St. Thomas Aquinas who sought a reconciliation of Aristotle’s rationalism and Christian theology. A major implication of Aquinas’ success was the acceptance by scholars within the universities and the Church that both reason and faith serve as sources of human knowledge. William of Ockham extended the Scholastic movement and his predecessor Roger Bacon by presented a law of parsimony in scientific explanation, which in turn laid the foundation of empirical science.

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.

Peter Casarella presents the themes in Joseph Ratzinger/Benedict XVI’s reflection on conscience. An important part of Benedict’s theory is his theology of culture. Current ideas about conscience and culture minimize truth. Benedict posits that conscience is a law on the heart and is not merely consciousness. He submits that culture points to the unveiling of a Redeemer. He proposes “interculturality,” the meeting of cultures in which their hope for Advent is kept. Regarding truth and conscience, Benedict works with Newman and Socrates. He concludes that conscience is the voice of truth in the subject. Benedict’s theory of conscience hews the Thomistic line between synderesis and conscience as an act of judging upon a good. Benedict guards against relativism by suggesting that synderesis can be known by the Platonic idea of anamnesis: memory of the true and good. This is tied to Benedict’s anthropology, namely humans’ reliance upon God and capacity for dialogue with Him. Though social circumstances can be sources of moral knowledge, the person should consult God’s will. Consciences are formed through Scripture, the Holy Spirit, the magisterium, beauty, and identification with Christ.

Christian Brugger treats a question of Catholic theology: the sensus fidei (the sense of the faith) in relation to conscience. Some theologians have claimed that when a significant number of the faithful conclude about a matter of faith or morals, they are expressing the sensus fidei, which merits recognition. Thus, such a conclusion can unfailingly inform the conscience. The sensus fidei has a long history but was noticeably used in Lumen Gentium from the Second Vatican Council. There it concerned the capacity of the baptized to know the truths of the faith, by the Holy Spirit. It is an intellectual power, however many false ideas about it followed the Council. Properly understood, the sensus fidei is inclusive of the teachings of Jesus and the Church about right and wrong. It is about the Church as a whole and is witnessed by consent of the whole Church – lay, hierarchy and religious. It can be blunted by poor liturgy and formation. It is limited to matters of faith and morals, and attendant to building up the Church. When properly exercised, it is one of the ways the Church can speak infallibly about what is to be believed.