1. Because individual members of the Church can err, and erring individuals can form movements of opinion, factions within the Church have often disagreed about what belongs to Catholic faith. Typically, all claim to express the same faith and to be committed to the attempt to live up to it, yet diverse parties dispute over the appropriateness of particular expressions and actions. This spectacle has always been repugnant to those who wish to live redemptively, for it diminishes the effectiveness of Christian life as a sign of divine love and truth. In such circumstances, the role of the magisterium is especially important. The unified witness of the bishops in matters of faith and morals enjoys the infallibility of the Church.
2. Vatican II clearly states the criteria for an infallible exercise of the magisterium by the bishops engaged in their day-to-day work of teaching: “Although the bishops individually do not enjoy the prerogative of infallibility, they nevertheless proclaim the teaching of Christ infallibly, even when they are dispersed throughout the world, provided that they remain in communion with each other and with the successor of Peter and that in authoritatively teaching on a matter of faith and morals they agree in one judgment as that to be held definitively” (LG 25; translation supplied). (The Council’s development of this text and use in a footnote to it of four earlier documents are considered at the end of this question.)
3. The development of the conciliar text makes it clear that the first condition—that the bishops be in communion with one another and with the pope—does not mean that they must act formally as a single body, in a strictly collegial manner. It is necessary and sufficient that they remain bishops within the Catholic Church. The voice of the Church is identified, and distinguished from various voices within the Church, by the sacramental ordination and bond of communion which unite the bishops who share in uttering the Church’s teaching.
4. The second condition—authoritative episcopal teaching on a matter of faith and morals—requires that the bishops be acting in their official capacity as teachers, not merely expressing their opinions as individuals or as theologians. As for the subject matter of their teaching—“faith or morals”—the formula has a long history.24 It is sufficient here to say that nothing in the pertinent documents limits “morals,” in the sense intended by Vatican II, in such a way as to exclude specific moral norms, like that forbidding adultery.
5. The third condition—that the bishops agree in one judgment—identifies universality as a requirement for an infallible exercise of the ordinary magisterium. What is necessary, however, is the moral unity of the body of bishops in union with the pope, not an absolute mathematical unanimity such as would be destroyed by even one dissenting voice.25
6. Furthermore, if this condition has been met in the past, it would not be nullified by a future lack of consensus among the bishops. The consensus of future bishops is not necessary for the ordinary magisterium to have taught something infallibly or to do so now. Otherwise, one would be in the absurd position of saying that it is impossible for there to be an infallible exercise of the magisterium until literally the end of time; since at any given moment, one cannot tell what some bishops in the future might say.
7. The fourth condition—that the bishops propose a judgment to be held definitively—obviously does not refer to the formulation and promulgation of a solemn definition, since what is in question is the bishops’ day-to-day teaching. The condition does mean at least this: that the teaching is not proposed as something optional, for either the bishops or the faithful, but as something which the bishops have an obligation to hand on and which Catholics have an obligation to accept. In the case of moral teaching, however, it is unlikely that those proposing the teaching will explicitly present it as something to be intellectually accepted as true; it is more likely that they will leave this demand implicit and will propose it as a norm which followers of Jesus must try to observe in their lives.
8. Vatican II’s teaching on the infallibility of the ordinary magisterium is not new in substance. Catholics have always believed that the apostles and their successors enjoy an unfailing gift of truth in proclaiming Christ’s teaching. As early as the fifth century, St. Vincent of Lerins tried to formulate the conditions for an infallible exercise of the ordinary magisterium (see FEF 2168 and 2174–75).
Very frequently the consensus of the Fathers of the Church is invoked in the Church’s teaching as a witness of faith which cannot be contradicted.26 The Fathers were bishops or closely associated with bishops; their writings as a body indicate what the bishops were teaching during the patristic period. The authority of the Fathers is an instance of the authority of the ordinary magisterium; their consensus in proposing a point of faith or morals to be held definitively makes it clear that the conditions for the infallibility of the ordinary magisterium were met.
9. If one considers that the Church as a whole is infallible in believing and handing on the faith, and also that the bishops as leaders of the Church are her legitimate spokesmen, then the infallibility of the teaching of the bishops under the conditions articulated by Vatican II follows. To deny it is to deny either that the Church is infallible or that the bishops really do exercise the role of apostolic leadership. For if they do exercise this role, they surely cannot all err and call upon the faithful as a whole to accept their error as the truth of the Lord Jesus.
An examination of the development in the conciliar process of the text from Lumen gentium, 25, discussed above makes clear two things the Council is not saying here: first, that a strictly collegial act is necessary for an infallible exercise of the ordinary magisterium; second, that such an exercise of the ordinary magisterium can occur only when something divinely revealed is proposed for acceptance with the assent of divine faith. Had the Council said either of these things, it would have limited the possibility of the infallible exercise of the ordinary magisterium of the bishops. In fact, it said neither.
The unity required of the bishops is unity in communion and judgment. The relevance to revelation required for infallible teaching is that the matter be one of faith or morals, either included in revelation or required to explain and safeguard what is expressly revealed.27 Hence, if the teaching of the bishops meets the stated conditions, one cannot argue that it is not infallibly proposed merely because they did not formally act as a body or because one cannot see precisely how a particular point is included in or implied by divine revelation.
To understand the conditions enunciated by Vatican II, it helps to look at the four documents cited in note 40. The first is a passage from Vatican I’s constitution on the Catholic faith: “Further, all those things are to be believed with divine and Catholic faith which are contained in the word of God, written or handed down, and which the Church either by a solemn judgment or by her ordinary and universal magisterium proposes for belief as divinely revealed” (DS 3011/1792; translation mine). Because this constitution concerns divine revelation, this solemn teaching is limited to matters divinely revealed, to be accepted with divine faith. Nevertheless, the passage has a bearing upon Vatican II’s teaching on the infallibility of the ordinary magisterium. It makes it clear that one must believe not only those things which are defined, but also certain things taught by the ordinary magisterium.
In recent years, many have said or assumed: “This teaching has not been defined; therefore, it is not infallibly taught, and it could be mistaken.”28 This argument is incompatible with what Vatican I and Vatican II teach, for it overlooks the possibility that a teaching which has never been defined is proposed infallibly by the ordinary magisterium.
The note of Vatican II next cites a passage added to Vatican I’s first schema On the Church, namely, a text drawn from St. Robert Bellarmine. Vatican I’s document on the Church was never completed, but it has the weight of Vatican II’s use of it to illustrate its own teaching. Rejecting limits on infallibility urged by some Protestants, Bellarmine writes: “Therefore, our view is that the Church absolutely cannot err, either in things absolutely necessary [for salvation] or in other matters which she proposes to us to be believed or to be done, whether expressly included in the Scriptures or not. And when we say, ’The Church cannot err,’ we understand this to apply both to the faithful as a whole and to the bishops as a whole, so that the sense of the proposition, The Church cannot err, is this: that what all the faithful hold as of faith, necessarily is true and of faith, and similarly what all the bishops teach as pertaining to faith, necessarily is true and of faith.”29 Two things must be noted about this. First, Bellarmine refers both to things which are to be believed and to things which are to be done. Second, he does not limit infallibility to matters explicitly contained in Scripture or to matters which are absolutely essential for salvation.
The third document cited is Vatican I’s revised schema for its never-completed constitution On the Church of Christ, together with a commentary by Joseph Kleutgen. The formula prepared in this schema would have defined the infallibility of the ordinary magisterium in terms very close to those in which Vatican II teaches it. Where Vatican II uses the expression “to be held definitively,” Vatican I’s formulation would have been “held or handed down as undoubted.” Both expressions leave room for the infallible teaching of propositions not expressly revealed, if they are necessary to explain and defend revealed truth. Kleutgen’s commentary discusses this point at length, arguing among other things that the Church can infallibly teach moral truths, whether or not they are included in divine revelation.30
The fourth text to which Vatican II’s note 40 makes reference is a document of Pius IX (see DS 2879/1683), in which the same point is made as in Vatican I’s subsequent solemn teaching: Faith is not limited to defined dogmas.
24. See M. Bévenot, “Faith and Morals in Vatican I and the Council of Trent,” Heythrop Journal, 3 (1962), 15–30; Piet Fransen, S.J., “A Short History of the Meaning of the Formula ‘Fides et Mores,’ ” Louvain Studies, 7 (1979), 270–301. The formula in Vatican I and II certainly includes reference to specific moral norms under “mores,” and in Trent and before, when “fides” was understood more existentially and less rationalistically, under “fides.” See Teodoro López Rodriguez, “ ‘Fides et mores’ en Trento,” Scripta Theologica, 5 (1973), 175–221; Marcelino Zalba, S.J., “ ‘Omnis et salutaris veritas et morum disciplina’: Sentido de la expresión ‘mores’ en el Concilio de Trento,” Gregorianum, 54 (1973), 679–715.
25. At Vatican I, Bishop Martin of Paderborn, speaking for the Deputation of Faith, explained the unanimity required for the infallibility of the ordinary magisterium (which Vatican I teaches: DS 3011/1792) by using the following example: All Catholic bishops believed in the divinity of Christ before the Council of Nicaea, but this doctrine was not defined until then; therefore, up to that time it was taught by the ordinary magisterium: J. D. Mansi et al., ed., Sacrorum conciliorum nova et amplissima collectio, 51:224–25. As everyone knows, there hardly was anything like unanimity about this doctrine either before or even after Nicaea, except to the extent that those who denied it may have ceased to be Catholic bishops, having lost communion by their heresy.
26. See DS, Latin edition, index item A 7 ad, for a list of explicit appeals to the authority of the Fathers in Church teachings.
27. See John C. Ford, S.J., and Germain Grisez, “Contraception and the Infallibility of the Ordinary Magisterium,” Theological Studies, 39 (1978), 264–69, esp. 268–69, n. 29. My own view is that everything infallibly taught is somehow included in revelation, for I consider revelation to be the living, personal reality communicated by Jesus and present in all its vitality throughout the Church and its entire history. Thus the seeming novelty of points needed to expound and safeguard what already is accepted as revealed does not prevent these points also from being parts of revealed truth—new shoots from the old vine.
28. Many theologians who disagree with received Catholic moral teaching are quite imprecise and ambivalent when they deal with the question of its possible infallibility. For example, Daniel C. Maguire, “Morality and Magisterium,” in Curran and McCormick, eds., Readings in Moral Theology: No. 3, mentions and raises some difficulties about the infallibility of the ordinary magisterium near the beginning of his article (37–38), a few pages later ignores the infallibility of the ordinary magisterium and implicitly equates infallible teaching with defined doctrine (42–43), and then goes on to question the very possibility of infallibility, particularly but not only in the moral domain (43–45).
29. In Mansi, ed., op. cit., 579 C (translation my own).
30. Ibid., 53:313 AB (Vatican I’s schema); 324–31 (Kleutgen’s commentary). I gave reasons (7‑B) for thinking all natural law is part of revealed truth. If this is accepted, an argument like Kleutgen’s is unnecessary; if not, then his approach (and the important fact that Vatican II carefully leaves room for continuing to take it) closes the door against those who would argue that points of natural law fall beyond the Church’s authority to teach on moral matters.