Conscience, according to Saint Thomas Aquinas, is the act of the human intellect by which “we judge that something should be done or not done.”1 This judgment is to be based on our knowledge of what is right and wrong for us to do, knowledge that we acquire both from our natural God-given ability to discern right from wrong (natural law) and from the truth about right and wrong that God has revealed to us through Scripture and Tradition (divine law). When we make correct judgments of conscience and act accordingly, we participate in God’s wisdom and act in accord with God’s will. Pope Saint John Paul II has referred to this human participation in the law of God as participated theonomy.2 In a similar vein, the Second Vatican Council document Gaudium et Spes calls conscience, “Man’s most secret core and his sanctuary. There he is alone with God whose voice echoes in his depths.”3 When we act according to correct judgments of conscience, we act from the depth of who we are as free persons who are at once masters of our own acts and children of our heavenly Father.

A person’s conscience is to be respected and protected as an essential element of that person’s human dignity. Barring exceptional circumstances, no one should compel another person to act against her conscience. A person’s conscience is her honest judgment about what is right and wrong to do. To act against one’s conscience is to do what one honestly thinks to be wrong. For that reason, conscience is said to be binding. Everyone is morally bound to do what he think is right. Even if someone is in fact wrong, that person is bound to do what he honestly thinks is right.

This doesn’t mean that a person who follows his errant conscience is necessarily excused from guilt. Such a person may or may not be morally responsible for the wrong he does, depending on whether that person should have known better. We are duty bound to follow our consciences, but we are also duty bound to form our consciences. Errant judgments of conscience are without excuse if we have not make an honest effort to discover what is truly right and good.

According to the Catechism of the Catholic Church, “Conscience must be informed and moral judgment enlightened.”4 The duty of forming one's conscience is a prerequisite for living a morally upright life. At the same time, “The education of conscience is a lifelong task”5 that we are to engage in with the help of parents and teachers, with the benefit of experience and moral maturity, and guided by the light of God’s Word and the authoritative teaching of the Church. Such an education leads a person to authentic virtue and the freedom to act with excellence in concert with the Divine Wisdom “whose voice echoes in his depths.”

This understanding of human conscience is the basis for correctly understanding and applying what bioethicists have called the Principle of Autonomy, by which they mean “the right to make moral decisions that affect oneself” that are “free from interference by others.”6 In the medical context, the right to autonomous decision making is seen as belonging primarily to patients. Patients should be free to make decisions about their own health care without interference from others. This right can be seen to be both based on and limited by a Catholic understanding of human conscience.

The right of a patient to autonomous decision making is founded on her right to follow her conscience. To make judgments of conscience and act on them is to exercise the rationality and self-determination that are at the core of human dignity. At the same time, to make well-formed judgments of conscience and act on them it to participate in the wisdom and freedom of God. To prevent a human person from following his or her conscience is therefore to prevent that person from exercising the aspects of his or her personhood that are most authentically human and most approximately divine. Such restriction of personal freedom is usually oppressive and generally to be avoided.

A patient’s autonomy is limited, however, by the involvement of other human beings in that patient’s care. Doctors, nurses, and family members have consciences too. Those who approve, perform, or consent by proxy to a course of action desired by a patient cannot set their own consciences aside. These people are bound by the same duty as the patient both to form and follow their consciences. They, no less than the patient, must follow their honest judgments about what should be done, and thus remain true to their own dignity as autonomous human beings and children of God.

1 Summa Theologiae I, q. 79, a. 13.

2 Veritatis Spendor 41.

3 Gaudium et Spes 16.

4 Catechism of the Catholic Church 1783.

5 Catechism of the Catholic Church 1784.

6 Ashley, deBlois, and O’Rourke, Health Care Ethics 5th ed.,

  p. 257.