Piet Fransen’s Research on Fides et Mores

David Stagaman, S.J. Theological Studies, 64, 2003, pp. 69-77

DAVID STAGAMAN, S. J., is docteur en théologie from the Institut Catholique de Paris. He is chair of the department of theology and professor at Loyola University, Chicago. His areas of special interest include ecclesiology, trinitarian theology, and the thought of Wittgenstein. He has recently edited Wittgenstein and Religion: A Bibliography and several articles. He is currently working on “Empowering the Urban Poor in Metro Manila,” based on interviews with people at NGOs there, a project of the University of California, directed by Richard Madsen.

[At Vatican I fides et mores were key terms, ordinarily translated as “faith and morals” and understood as separable terms. Were they always so distinguished? Did mores traditionally mean “morals”? Piet Fransen traced their origin to a letter of St. Augustine and followed their use through the Middle Ages to the Council of Trent. Afterwards, the meaning of mores changed from ecclesiastical customs to morals; fides became a concept rather than the lived faith of the Church.]

AT THE First Vatican Council, in the dogmatic constitution Pastor aeternus, it is decreed that: “we teach and define as a divinely revealed dogma that when the Roman pontiff speaks ex cathedra, that is, when, in the exercise of his office as shepherd and teacher of all Christians, in virtue to be held by the whole church, he possesses . . . that infallibility which the divine Redeemer willed his church to enjoy in defining doctrine concerning faith or morals. . . . It is divinely revealed dogma that the Roman Pontiff when he speaks ex cathedra, that is, when acting in the office of the shepherd and the teacher of all Christians, he defines, by virtue of his supreme authority, a doctrine concerning faith and morals to be held by the universal Church” (DS 3074).(1)

The Latin terms used in the official text, fides et mores, is the subject of my inquiry. (2) Archbishop Vinzenz Gasser, the Secretary of the Deputation of the Faith, the council’s theological commission, in his official commentary, stated that the meaning of fides et mores was quite evident, i.e. well known, to the theologians. (3) What is that evident meaning? In regard to the latter term, Reidl has argued that mores was understood by the Council Fathers as morals. Furthermore, they saw mores as a part of fides where faith extends its domain into the matters of moral responsibility. (4) Joseph Kleutgen, whose influence at the council cannot be underestimated, confirms Reidl’s view and adds that Vatican I confined its proclamation to the primary object of infallibility, i.e., moral principles that have been expressed in divine revelation. (5) The late Flemish Jesuit theologian Piet Fransen (1913–1983), in a valuable historical study, observed that fides et mores, as used in the above passages, might best translate as “faith or morals.” Here I intend to follow Fransen’s guidance as he asked: did fides et mores always have the meaning that Vatican I ascribed to these terms?

Before we examine the history of fides et mores, we should note that Vatican I used the terms twice in other contexts. This occurred when the dogmatic constitution Dei Filius confirmed what Trent has said about the authority of the Church in the interpretation of the Bible (DS 3007). Also, in an earlier section of Pastor aeternus, the Council Fathers asserted:“ . . . this not only in matters concerning faith and morals, but also in those which regard the discipline and government of the Church throughout the world” (DS 3060). The bishops were speaking of the papal jurisdiction and wished to affirm that its primacy involved both faith and morals as well as discipline in and reform of the Church. (6)

Augustine, Bishop of Hippo

According to Fransen, Augustine was the first to use the phrase fides et mores in two letters to a layman named Januarius who was deeply worried about the liturgy and practice of Christian life in the Church. Specifically, he had focused on the date of Easter: why is its dating dependent upon the Jewish Sabbath and the phases of the moon?

In Epistola 54, Augustine responded as follows: “The best rule of conduct for the earnest and intelligent Christian is to follow the practice of the local community wherever he happens to be.” He, then, added: “And what is not evinced to be against the faith (fides) or against the good usages (bonos mores) should be taken indifferently (i.e., as not binding) and should be observed taking into account the community one is living with.” (7) Augustine’s advice here to Januarius probably reflects the counsel that Ambrose had given Augustine’s mother when Monica became deeply disturbed that in Milan Christians did not fast on Saturday whereas in Carthage they did. Ambrose had told her: “When I am in Rome, I fast on Saturday; when in Milan, I don’t. You do the same. So, whenever you are visiting a church, follow its customs if you don’t wish to scandalize the others, or be scandalized by them.” (8)

In Epistola 55, Augustine elaborated on his earlier advice: “There is further one very healthy rule in the matter: whatever is not against faith (fides) and the good usages (mores) and contains some suasions for bettering one’s life, whenever we see that they are being introduced (instituti) or have already existed, we do not intend to reprove (improbare); but accept them with favor, and keep them, as long as the weakness of some leave them open to scandal.” (9) For Augustine, these good usages are found in the Scriptures and the decrees of the episcopal councils (especially, Nicaea and Chalcedon where he thought that the whole Church had been represented). Derived from these two sources, these traditions became universal in the Church; and their very universality manifested the apostolic origin of the tradition in question.

Piet Fransen drew the following conclusions about Augustine’s use of fides et mores:

There is no doubt about the meaning of mores. The term has nothing to do with so-called “morals,” and even less with “natural law or ethical principles” as some people may think. It simply refers to the manifold forms of Christian life, especially sacramental and liturgical, as rooted in the living tradition of the Church. . . . By “faith” Augustine meant the body of doctrines, universally accepted by the Church, that is, the living concrete life of faith of the Christian communities under the guidance of their bishops, their priests and theologians and other competent persons. (10)

In other words, fides et mores denoted the living fidelity of Christians in their lives to the depositum fidei handed down from Christ and his apostles. In no sense did the terms allude to any kind of juridical succession. And this living fidelity was linked to the Church’s indefectibility. (11)

The Middle Ages

While the medievals did not make frequent use of fides et mores, they did express ideas similar to those of Augustine. Explicit usages of the terms under consideration here appear rarely in this period. (12) Thomas Aquinas also used the terms. In his Commentary on the Psalms (48, 2) where he considers them as the substance of the tradition, which places limits on the exercise of the Church authority.(13)

In regard to fides, the medievals used frequently the expressions “secundum fidem” and “contra fidem.” At issue here is the fides quae, the content of the faith rather than the act of faith, which has preoccupied modern theologians. This fides occupied a middle position between opinio and scientia. It possessed the certitude of the latter while involving the obscurity or lack of evidence of the former. The truths of faith were contained in the creeds (that of the Apostles Creed, the Nicene-Constantinopolitan Creed, and especially the Athanasian Creed), the teaching of the saints (the testimonia sanctorum which meant the Church Fathers and the great theologians of the past), the first four councils (to which Gregory the Great had attributed an authority equal to that of the four Gospels), and any related truths whose rejection might endanger either faith or the universal laws of the Church. All these truths as propounded by the Church were necessary because Christians were morally obliged to accept them in order to be saved. They constituted an extensive scale of truths embodied in the living

Tradition of the Church’s faith. This extensive body of truths of faith was characterized by its universality and its inner cohesion or unity. The universality and inner cohesion guaranteed the apostolicity of the fides of the faithful because the fidelity exhibited in their lives indefectibly linked them to the message of Jesus Christ.

The preferred terminology in the Middle Ages was articuli fidei et sacramenta. Articles of faith referred to the three cited creeds; sacraments denoted the seven sacraments (including their administration). Both these articles of faith and the sacraments belonged to the living unity of the Apostolic Tradition. Magisterial documents of the period often distinguished among articles of faith (with special emphasis on the Trinitarian and christological dogmas), the sacraments (used in the same sense as above), and “decretals” which stipulated reforms for Christian life in the Church. (14)

Yves Congar pointed out that the medieval faith consisted of the content of the tradition found whole and entire in the Scriptures as read by the Church and in the oral Apostolic Tradition. “Scripture” included the“christological explanation of the Old Testament and the ecclesial understanding of the mystery of Christ and the Church as witnessed to by the Scriptures.” The Apostolic Traditions generated liturgical and disciplinary practices, which were held universally and were bound up in the Church’s life. For this mentality, divine revelation was communicated in realities, and not just in words. (15)

Finally, it should be noted that Christian life and its concomitant practices were experienced concretely. They embraced the entire existence of the baptized. Thus, medievals saw their faith and customs (or articles of faith and sacraments) present in a Christian Commonwealth, which was structured and ruled by “the Lords spiritual and temporal.” Heresy arose when some individual or a group obstinately refused to conform to the social and hierarchical order established in God’s wisdom and mercy. This commonwealth, however, was not perfect. It was infected by sinfulness and remained in continuous need of reform. Hence, medieval men and women felt free to criticize this commonwealth, including its ecclesiastical dimension. A special target of their criticism was the clergy and monks. (16)

The Council of Trent

The Council of Trent twice invoked the phrase fides et mores at the fourth session on April 8, 1546. The first instance occurred in “The Decree on the Acceptance of the Sacred Books and Apostolic Traditions” where it is stated: “the council accepts and venerates with a like feeling of piety all the books of both the old and the new Testament, since the one God is the author of both, as well as the traditions concerning both faith and conduct (nec non traditiones ipsas, tum ad fidem, tum ad mores pertinentes), either spoken directly by Christ or dictated by the Holy Spirit, which have been preserved in unbroken sequence in the catholic church” (DS 1501).

The second passage can be found in the “Decree on the Acceptance of the Latin Vulgate Edition of the Bible, Rule on the Manner of Interpreting the Scriptures.” The relevant passage reads that “no one, relying on his own personal judgment in matters of faith and customs (in rebus fidei et morum) which are linked to the establishment of Christian doctrine, shall dare to interpret the sacred scriptures . . . by twisting its text to his individual meaning . . . ” (DS 1507).

Fides at Trent meant the content of truth contained in the gospel of Christ; mores embraced the practices and customs of the apostolic Church, i.e., unwritten traditions embodied in doctrine, discipline, and liturgy. Together fides et mores comprised the deposit of faith entrusted to the Church from its inception; they included the doctrine and forms of Christian life whose unity and cohesion originated in the fact that they were inspired by the one Spirit of Jesus Christ.

This broad interpretation of fides et mores, which began with Augustine and continued through the Council of Trent, can be found in a number of post-Tridentine theologians: Melchior Cano, Robert Bellarmine, and Francisco Toledo. (17)

How and Why Did the Meaning of Fides et Mores Get Changed?

An intermediary figure in the change is the Jesuit theologian Francisco Suárez. First and foremost, he distinguished between two aspects of the tradition: the doctrinal and the moral. When he used the term mores, he spoke of a moral tradition, which consisted of moral precepts, which had been handed down to us from Christ and his Apostles. From Suárez, the path was opened toward a supernatural faith as it was understood at Vatican I. Fides came to be seen as a supernatural way of discovering the truth about things which was exclusively illuminated by God’s revelation. Fides was set in opposition to all forms of natural knowledge where truth was attained through the “light of reason.”

After the Enlightenment, Roman Catholic theologians insisted that believers could not experience the gracious presence of God in their innermost being unless they had received an infused mystical grace. As a result, theologians drew a sharp distinction between pure nature and the supernatural, and the latter became the action of God upon human beings without their experiencing that action. Thus, a spiritual, mystical tradition in theology which had insisted that divine grace was and could be experienced by the recipient was excluded from theological reflection. As a result, theologians began discussing a fides implicita, a faith possessed by the simple faithful which drew its sustenance from the authority of the magisterium. (18)

Three witnesses to this change stand out. They are Philippus Neri Chrismann (1751–1810) who published his Regula fidei catholicae in 1792; François Véron (1578–1649) in Règle générale de la Foy, published in 1646; and Henry Holden (1596–1662) who, in 1652, brought out Divinae fidei analysis. Thus, we have testimony from Germany, France, and England of a consensus that faith was a purely supernatural action without any natural, i.e. experiential, correlative. This trend came to fruition in the work of Stephen Wiest (1748-1797), for whom fides et mores meant dogmatic doctrine and Church discipline. Wiest had an enormous amount of influence on Giovanni Perrone, S.J., of the Roman School, who played an important role at Vatican I.(19)

In addition to this theological development, Yves Congar has called our attention to a number of other factors that promoted the change. First of all, he cited the investiture controversy of the 11th century, plus the Renaissance and the Reformation in the 16th century. All three of these factors contributed to a polarization of papal and episcopal authority. During the Renaissance, the re-discovery of Roman law precipitated an emphasis on the personal exercise of authority and provided such exercise with a juridical cast.

Secondly, in the 19th century, Popes Gregory XVI and Pius IX, confronted by emerging secular states that acknowledge no authority above themselves, argued for greater attention to church authority. They especially appealed to their own supreme sovereignty as a sure means of clarifying for the faithful what were the true traditions of the Church. Gradually, teaching authority in the Church came to be concentrated in one person whose power was first and foremost jurisdictional. This clarification of the Church tradition through competent ecclesiastical authorities which was unknown in much of the Church’s history, appeared to be tolerated throughout the Church because only a handful of truly Roman Catholic nations remained in Europe and most countries where the gospel was being proclaimed were considered mission territories.

Congar contrasted this 19th-century development with roughly 15 centuries in which fides et mores denominated an ecclesial reality where the“living Tradition” of the Church played a key role, and bishops functioned as privileged witnesses to the nature and content of that reality. This “living Tradition” was justified by its internal harmony. Congar added that this view of the Tradition perdures in the churches of the East today; and that the mutual excommunications of the 11th century contributed to the eventual narrowing of the understanding of fides et mores. (20)

Vatican II

Given these developments, the Second Vatican Council used the terms in two different ways. In Lumen gentium, the council adhered to the meaning adopted by Vatican I. This interpretation stands out in the two places where Vatican II appealed to fides et mores. In Lumen gentium no. 12, the council, speaking of the sensus fidei of the faithful, acknowledges its significance when it attains universal agreement in the matters of faith and morals (the Council Fathers also emphasize the supernatural character of this sensus on such occasions). In no. 25 the constitution states that bishops, dispersed around the world but in union with Peter’s successor, can teach authentically and infallibly on matters of faith and morals if they coalesce in a single viewpoint and insist that this view be held definitively (in no. 48, they say that this is true even more so when these bishops and the pope are gathered in ecumenical council).

In Dei Verbum, the Council reflects a more Tridentine approach to fides et mores. This approach is obvious in no. 7 when they assert that Christ the Lord commissioned the Apostles to preach the gospel. That the use of fides et mores in this chapter derives from the earlier tradition is confirmed in the elaboration of the meaning of this commission in the remainder of no. 7 and in no. 8.21


When speaking of fides, Fransen noted: “We may describe it [the meaning of fides] as a shift from a more comprehensive, more complex and more concrete meaning towards a more specific, more technical and precise, even towards a more national [sic] (22) and therefore abstract meaning.” (23) The same could be said of the shift in the meaning of mores. (24) Furthermore, the understanding of fides et mores became more conceptual and less connected with a “living Tradition”; this conceptualization no doubt resulted from the attempts on the part of the church officials and its theologians to respond to the Enlightenment and 19th-century rationalism. Finally, the shift in meaning and toward a more conceptual understanding was accompanied by a greater stress on the jurisdiction of the teaching magisterum in keeping the faithful loyal to the original message of Christ regarding fides et mores. (25)


1. The English version of this constitution and further conciliar statements is cited from the translation of Norman Tanner, Decrees of the Ecumenical Councils, 2 vols. (Washington: Georgetown University, 1990) 2.816.

2. Piet Fransen, “A Short History of the Meaning of the Formula ‘Fides et Mores’,”Hermeneutics of the Councils and Other Studies, collected by H.E. Mertens & F. de Graeve (Leuven: Leuven University, 1985) 287–318. This essay had earlier appeared in the Louvain Studies 7 (1978–1979) 270–301. In this note I am following quite closely this essay. Fransen first explored this topic in a paper, “Unity and Confessional Statements,” that he delivered at a meeting of Jesuit ecumenists in Dublin (August, 1971). The papers of that conference were published as The Dublin Papers on Ecumenism, ed. Pedro S. de Achútegui (Manila: Loyola School of Theology, 1972) 35–82.

3. Bishop Vinzenz Gasser (1809-1879) in his Official Relation on Infallibility at Vatican Council I (replying to suggestion # 45) in The Gift of Infallibility: The Official Relatio on Infallibility of Bishop Vincent Gasser at Vatican Council I, trans. with commentary by James T. O’Conner (Boston: Daughters of St. Paul, 1986) 68–69.

4. Alfons Riedl, Die kirchliche Lehrautorität in Fragen der Moral nach den Aussagen des ersten Vatikanischen Konzils (Freiburg: Herder, 1979) 269–71.

5. Kleutgen believed that natural law was contained in revelation. See John Boyle, Church Teaching Authority: Historical and Theological Studies (Notre Dame: University of Notre Dame, 1995) 44–49. See also Joseph Kleutgen, Die Theologie der Vorzeit verteidigt, vol. 1, 2nd ed. (Innsbruck, 1878; orig. ed. Múnster: Theissing, 1867–1874).

6. Fransen, “Short History” 307–8.

7. Ad inquisitiones Januarii, 54, II, 2 (PL 33.200; CSEL 34.159–160). English translation from F. van der Meer, Augustine the Bishop, trans. Brian Battershaw and G.R. Lamb (New York: Sheed & Ward, 1961) 295–96.

8. Ad inquisitiones Januarii, 54, II, 3 (PL 33.200; CSEL 34. 160–161).

9. Ibid. 55, XVIII, 34 (PL 33.220–221; CSEL 34.207, 9–17). See Fransen, “Short History” 291 n. 31

10. Fransen, “Short History” 293–94.

11. Ibid. 294.

12. Fransen cites Brian Tierney, Foundations of the Conciliar Theory (49, n. 4) as saying that Gratian, in his Decretals, quotes Augustine when speaking of the ecclescastical customs. The footnote does not appear in the enlarged new edition of Tierney’s work. Furthermore, a search for all case forms of fides et mores in the Concordantis canonum discordantium also known as Decretum aureum revealed no used (sic) by Gratian. See Fransen, “Short History” 295, n. 26.

13. Super Psalmos, 48, 2: “quando praedicamus fidem et mores, docemus res.

14. Fransen, “Short History” 296–300.

15 .Yves Congar, Tradition and Traditions, trans. Michael Naseby and Thomas Rainborough (New York: Macmillan, 1967, orig. French ed. 2 vols. Paris: Fayard, 1960–1963) 63. See Fransen, “Short History” 301–2, and nn. 46–48.

16. Fransen, “Short History” 302–3.

17. Ibid. 304–8, 310.

18. Ibid. 313–14.

19. Ibid. 309–11.

20. Tradition and Traditions 177–229; see also Congar’s “The Historical Development of Authority in the Church: Points for Reflection,” in Problems of Authority, ed. John Todd (Baltimore: Helicon, 1962) 119–50.

21. Fransen, “Short History” 314–17.

22. I presume he meant to write “notional.”

23. Fransen, “Short History” 309.

24. My own opinion is that the interpretation of fides et mores at Vatican I is a clear instance of development of doctrine. On this, see my Authority in the Church (Collegeville: Liturgical, 1999) 115.

25. Fransen, “Short History” 312–18.