1. Church documents never use the word “conscience” to mean superego or awareness of social convention.5 The Church is interested in conscience only in the third sense, as the ability to know moral truth.
2. In Scripture the judgment of conscience often is attributed to the “heart” (see Jb 27.6; Ps 16.7), which receives and retains God’s law (see Dt 6.6–9; Ps 37.31; 40.9; Prv 7.1–3) and which can be enlightened by his gift of wisdom (see Ps 90.12; Prv 2.9–11). Again, the work of conscience in Christian life is assigned to the renewed “mind” (see Rom 12.1–2). But the technical term “conscience” seldom is used; indeed, no Hebrew word exists for this specific concept. In the New Testament “conscience” refers mainly to awareness of wrongdoing, especially the pangs experienced after one has done wrong.6
3. Although they lack divine revelation, even the Gentiles are said to have this awareness of right and wrong; it is part of the human make up created by God. Conscience, which is joined to knowledge of moral norms written in the heart, serves the Gentile as the demand of the revealed law serves the Jew (see Rom 2.14–16).
4. As a source of warnings, conscience is helpful for Christians, too, much as law is. But it is not infallible. A clear conscience does not necessarily mean one is justified (see 1 Cor 4.4–5); and one’s heart can charge one with something even though one is at peace with God (see 1 Jn 3.19–20).
5. Vatican II emphasizes the dignity of conscience, a dignity rooted in the law written in our hearts. We do not make this law; we discover it (see S.t., 1–2, q. 91, a. 3, ad 2). It consists of a group of moral principles which God gave us in creating us and which we can know naturally. Although this law written in our hearts is made up of general principles, it has implications for particular moral issues (see GS 16).
6. As used by Vatican II, “conscience” refers at once to awareness of principles of morality, to the process of reasoning from principles to conclusions, and to the conclusions, which are moral judgments on choices made or under consideration. St. Thomas uses a particular word for each: “synderesis” for awareness of principles, “practical reasoning” for the process of moving from principles to conclusions, and “conscience” for the concluding judgment only (see S.t., 1, q. 79, aa. 12–13; 1–2, q. 94, aa. 2, 6).
7. According to St. Thomas, conscience is an intellectual act of judgment. This judgment is primarily practical and forward-looking, corresponding to and guiding each choice one is about to make. Conscience is one’s last and best judgment concerning what one should choose. With this judgment in mind, one chooses, either in agreement with conscience or against it (see S.t., 1, q. 79, a. 13).7
8. Conscience plays a further role after choice. One compares the choice one actually made with one’s judgment as to the choice one ought to have made (for example, in examining one’s conscience). Even here, conscience is an act of knowledge, not to be confused with feelings of guilt or security, which may also be present.
9. Given this understanding of conscience, it is true by definition that one ought to follow one’s conscience. As one’s best judgment concerning what is right and wrong, an upright person has no alternative to following it. “Follow conscience” does not indicate one possible source of moral guidance in contrast to some other possible source or sources; supposing one thought in some case that it was better to follow a norm other than that previously provided by conscience, by that very fact the new norm would become one’s real judgment of conscience.
The teaching of Vatican II on conscience is mainly contained in one article of the Pastoral Constitution on the Church in the Modern World (GS 16). It deserves close reading. “In the depths of his conscience, man detects a law which he does not impose upon himself, but which holds him to obedience. Always summoning him to love good and avoid evil, the voice of this law can when necessary speak to his heart more specifically: do this, shun that. For man has in his heart a law written by God. To obey it is the very dignity of man; according to it he will be judged” (GS 16; translation supplied). At this point the Council refers to what is probably the most important passage in Scripture in which “conscience” occurs: “When Gentiles who have not the law do by nature what the law requires, they are a law to themselves, even though they do not have the law. They show that what the law requires is written on their hearts, while their conscience also bears witness and their conflicting thoughts accuse or perhaps excuse them. On that day when, according to my gospel, God judges the secrets of men by Christ Jesus” (Rom 2.14–16).
The law mentioned here is called “natural law” in Catholic teaching. It is known by everyone, even persons who do not have faith, for its demands are “written in their hearts”—that is, known spontaneously. Conscience here is a co-witness with the law. The two together will accuse or defend, which implies that they must agree with each other. Vatican II expresses the same idea in its image of conscience as a voice of the law written by God in the heart—God writing it by creating persons of human nature.
The use of the scriptural word “hearts” does not mean that conscience is considered by St. Paul or Vatican II a power of feeling what is right or a disposition to love what is good. “Heart” in the Bible has a much wider reference than in current English. The reference includes the whole of one’s interior life, including one’s mind and will.8
Vatican II continues with a metaphorical description of conscience taken from a document of Pius XII: “Conscience is the most secret core and sanctuary of a man. There he is alone with God, whose voice echoes in his depths. In a wonderful manner conscience reveals that law which is fulfilled by love of God and neighbor” (GS 16). Here the Council refers to the precept of love formulated in the New Testament (see Mt 22.37–40; Gal 5.14). Implicit is the statement: The law Christian love fulfills and must fulfill is the natural law (see S.t., 1–2, q. 99, a. 1, ad 2; q. 100, a. 3, ad 1; q. 105, a. 2, ad 1; S.c.g., 3, 117).
Since conscience expresses the natural law, which can be known by everyone, and since this law is objective, the Council proceeds to point out: “In fidelity to conscience, Christians are joined with the rest of men in the search for truth, and for the genuine solution to the numerous problems which arise in the life of individuals and from social relationships. Hence the more that a correct conscience holds sway, the more persons and groups turn aside from blind choice and strive to be guided by objective norms of morality” (GS 16). Here the Council speaks of “correct conscience.” When correct, conscience demands that one be reasonable, not arbitrary; that one conform to objective or true norms, not to subjective substitutes chosen arbitrarily. But conscience is not always correct; the Council distinguishes two ways in which conscience goes wrong. (These will be considered in question C below.)
Vatican II teaches that every human person has a right to religious freedom (DH). This teaching often has been misunderstood and sometimes has been exploited to promote a false conception of freedom of conscience. John Courtney Murray, S.J., the theological expert whose work was most fruitful for the development of this document, comments: “It is worth noting that the Declaration does not base the right to the free exercise of religion on ‘freedom of conscience.’ Nowhere does this phrase occur. And the Declaration nowhere lends its authority to the theory for which the phrase frequently stands, namely, that I have the right to do what my conscience tells me to do, simply because my conscience tells me to do it. This is a perilous theory. Its particular peril is subjectivism—the notion that, in the end, it is my conscience, and not the objective truth, which determines what is right or wrong, true or false.”9 Vatican II does teach about conscience in this document (DH 3 and 14), but in a very traditional way.
5. For a rich summary of the scriptural and patristic sources which underlie the teaching on conscience of St. Thomas and Vatican II: Philippe Delhaye, The Christian Conscience (New York: Desclée, 1968), 36–99. For a concise statement of the meaning of “conscience” and criticism of certain prevalent errors: William B. Smith, “The Meaning of Conscience,” in Principles of Catholic Moral Life, ed. William E. May (Chicago: Franciscan Herald Press, 1980), 361–82. For a more extensive systematic treatment, rooted in classical moral theology but not entirely confined by it: Pietro Palazzini, La coscienza, Studi cattolici (Rome: Ares, 1961).
6. See C. A. Pierce, Conscience in the New Testament (London: SCM Press, 1955), 108–9. Pierce’s study, considered as a whole, suggests that, although the sacred authors spoke in a variety of ways concerning matters relating to conscience, no developed doctrine on conscience emerges. Some aspects of Pierce’s treatment need to be amended: Margaret E. Thrall, “The Pauline Use of Syneidesis,” New Testament Studies, 14 (1967), 118–25; also Ceslaus Spicq, O.P., “Conscience dans le Nouveau Testament,” Revue Biblique, 47 (1938), 50–80; W. D. Davies, “Conscience,” Interpreter’s Dictionary of the Bible, 1:671–76; and two articles in Encyclopedia of Biblical Theology: Ceslaus Spicq, “Conscience,” 131–34; J. B. Bauer, “Heart,” 360–63.
7. Also see St. Thomas Aquinas, De veritate, q. 17, a. 1. Anthony Battaglia, Toward a Reformulation of Natural Law (New York: Seabury Press, 1981), in a study which makes use of St. Thomas, fails to distinguish between social convention and moral truth, and thus reduces the moral “ought” to the “is” of cultural practices (134). As part of his reconstruction of natural law as a natural, psychosocial principle of conventional morality, Battaglia suggests that the objective reference of moral judgment, which takes us beyond “feeling good about ourselves” (69), is reached by a sense of fitness analogous to the aesthetic sense (79). Battaglia makes no distinction between the judgment of conscience and choice. In individual decision making, one arrives at “what makes sense,” he explains, by balancing the inputs of senses, emotions, intelligence, and intuition, to see what best satisfies these various and contradictory inclinations as a whole (102–9). The trouble with this is that it so generously and indiscriminately takes into account all aspects of human motivation that it is hard to see how one could possibly choose contrary to conscience—that is, commit a sin. Indeed, Battaglia says: “We must over and over again assert that human beings act according to what makes sense to them in the particular circumstances of their particular lives—or at least they try to” (104). The only possibility of immoral action he recognizes is a practice which does not arise out of social consensus (135), for such a practice violates the universalizability criterion as Battaglia understands it, and he thinks this criterion is the specific contribution of reason to moral judgment (108). Thus, even on this theory, conscience in the genuine sense emerges solely and precisely at the point where a rational requirement is violated.
8. In addition to Bauer’s article on “heart” cited above, see Johannes Behm, “kardia,” Theological Dictionary of the New Testament, 3:605–13. Since “heart” in the Bible embraces the whole inner self of the person, it can sometimes be replaced by “conscience.” But frequently such a substitution would be erroneous or at least questionable. Hence, one must be extremely careful about drawing conclusions concerning the scriptural teaching on conscience from passages in which “heart” occurs. One must be even more careful in using the word “heart” in teaching about conscience, since in English “heart” usually means sentiment rather than awareness of truth.
9. John Courtney Murray, S.J., n. 5 to his edition of “Declaration on Religious Freedom,” in The Documents of Vatican II, ed. Walter M. Abbott, S.J. (New York: America Press, 1966), 679.