The question “Does doctrine develop?” has caused the felling of many trees over the past two centuries. The question has become a vital one for modern Catholic thinkers for a variety of reasons. First, polemical conflict following the reformation of the sixteenth century, during which the Church was charged with abandoning the faith of the earliest Christians, demanded a Catholic answer. Second, the rise of modern historical studies impressed upon us the importance of seeing how ideas are shaped by the cultural forces that obtain at particular moments in history. In this light, it seemed to some that what the Church teaches simply changes according to those differing cultural forces. Third, the definition of papal infallibility in 1870, as well as the modern definitions of the Immaculate Conception and Assumption have made these questions all the more acute, both for many within the Church as well as for the Church’s external critics.
My argument here will draw heavily on the work of St. John Henry Newman, but I will complement his reflections by considering how far we can speak of development as a concern of early Christian writers. This will then enable me to consider how we might envision a notion of the Church’s growth in knowledge as a vital part of God’s revelatory economy.
The fourth century saw some of the great doctrinal formulae of the faith first promulgated. Before this period, for example, the Spirit is, of course, frequently spoken about; the Spirit’s role in strengthening our faith, in uniting us to Christ, in inspiring prophecy both ancient and new were frequent subjects of Christian writing. But it was only during the late fourth century that Christian writers came to assert that simply “the Holy Spirit is God,” and only then did the doctrine of the Trinity, as we have confessed it ever since, come to be stated unambiguously: God as three divine persons in one nature. A number of thinkers in these decades offer direct comments on such momentous change; I will consider two.
The first is Gregory of Nazianzus, or, as he became known in Eastern tradition, Gregory the Theologian. About the gradual emergence of clear statements that the Spirit is God he writes the following:
. . . growth towards perfection comes through additions. In this way the old covenant made clear proclamation of the Father, a less definite one of the Son. It was dangerous for the Son to be preached openly when the Godhead of the Father was still unacknowledged. It was dangerous too for the Holy Spirit to be made (and here I use a rather rash expression) an extra burden when the Son had not been received. It could mean men jeopardizing what did lie within their powers, as happens to those encumbered with a diet too strong for them or who gaze at sunlight with eyes as yet too feeble for it. No, God meant it to be by piecemeal additions, “ascents” as David called them, by progress and advance from glory to glory, that the light of the Trinity should shine upon more illustrious souls . . . you see how light shines on us bit by bit, you see in the doctrine of God an order, which we had better observe, neither revealing it suddenly, nor concealing it to the last.
Notice two things: first, Gregory treats the slow emergence of a full doctrine of the Trinity to be part of God’s own mode of revelation. God reveals himself to us in times and modes that are fitted to our capacity to understand. To quote a very useful recent discussion of this theme in early Christianity, “God uses time well.” God is both the orator who knows how to pluck at the heartstrings of his listeners so they will be persuaded and the doctor who knows what medicine will heal rather than kill the patient. The unfolding of revelation, then, has both historical context and a divinely governed order to which we should learn to be attentive. Just as the apostles themselves had to come by their knowledge of who Christ was by degrees, so there is also a wider economy within which the Spirit slowly draws us into all truth. When Gregory writes in this way, he is drawing on a long ancient rhetorical and philosophical appreciation for what is “fitting” or “appropriate.” Gregory is calling us to the importance of careful attention to what we are as human beings, and careful attention to the manner in which God leads.
Second, when Gregory speaks about doctrines developing, he is talking about a growth in knowledge. He does not envisage the development of which he speaks as a “change” in what Christians preach, but a “growth” in our understanding of divine realities. Moreover, this growth is not a matter of us becoming smarter, and certainly has little to do with our becoming better Christians, it is a matter of the manner in which God takes hold of us and reveals to us. Indeed, the understanding of which Gregory speaks is as much, I would argue, a potential growth in understanding as it is a growth simpliciter. By this I mean that Gregory does not think that our understanding of what is now drawn out for us by the Spirit automatically offers us insight; those who now confess Father, Son, and Spirit as the one God must learn to pray and speak this language well if they are to enter into the growth in understanding that is offered them.
We can summarize, then, by saying that Gregory sees an increasing penetration of Scripture’s depths, under divine guidance, to be a highly fitting arrangement. It is not only that each of us may learn more as we grow in faith, shaped by the vicissitudes of life and drawing on scripture’s depths, it is that there is a parallel in the life of the Church as a whole, and that life is governed by an economy of revelation known to God and under God’s providential care, even as it also is worked out in the course of human struggles to understand and human fights over meaning and interpretation.
Across the Mediterranean, in southern France, and a couple of generations later we meet St. Vincentius of Lerins. In the 430s Vincent (thus we will call him) wrote a text called the commonitorium, a Latin term that means an admonition, a calling to mind of important truths. Very near the beginning of his text, Vincent tells us that “in the Catholic church itself all possible care must be taken that we hold that faith which has been believed everywhere, always, by all.” This statement is often all that people know of Vincent, and it has often seemed somewhat naive to modern historically-minded commentators.
But there is a second and equally important principle that occurs much later in the text when Vincentius asks whether, if we believe only what the Church has always and everywhere taught, is there then “no progress (profectus) in Christ's Church?” The answer is direct:
Shall there, then, be no progress in Christ's Church? Certainly; all possible progress! For what being is there, so envious of men, so full of hatred to God, who would seek to forbid it? Yet on condition that it be real progress, not alteration of the faith. For progress requires that the subject be enlarged in itself, alteration, that it be transformed into something else. The intelligence, then, the knowledge, the wisdom, as well of individuals as of all, as well of one man as of the whole Christ, ought, in the course of ages and centuries, to increase and make much and vigorous progress; but yet only in its own kind; that is to say, in the same doctrine, in the same sense, and in the same meaning.
Along the same lines as Gregory, when Vincentius talks about profectus, he talks about growth in knowledge and wisdom; and the reason he asserts in such strong terms that there must be development is because he means growth in knowledge. Who would deny that Christians are able to grow in understanding of the words that they read in Scripture or confess in the Creed? But, of course, many problems arise as soon as he offers a parallel between the individual human being who grows and the Church as a whole. In particular, this parallel raises all sorts of questions about how one judges the community’s growth in understanding. Both Gregory and Vincentius were able to point to ecumenical councils guided by the Spirit as organs of discernment, but both also lived in times of theological turmoil, and fought hard for the positions that they best believed represented the faith delivered to them.
While there is growth in knowledge, Vincentius insists that truth growth is a growth “in the same doctrine, in the same sense and in the same meaning.” For many Catholic theologians in recent centuries, this has been a lodestar: if there is development, nevertheless, new expressions must indicate “the same meaning.” Of course, as you will have noted, the phrase is catching, but its meaning is not simply obvious: how does one know whether different expressions have the same meaning? Like Gregory, Vincentius relies on a notion of fittingness. The good of progress in knowledge is a God-given feature of human existence and one of which God (as its Creator) takes full advantage in the way that truth is revealed to us and understood by us. It is thus something of an aesthetic quality, captured most easily and directly by a metaphor or analogy. The judging of true growth, and the distinguishing of growth from diminishment is sometimes easy, but, more often than not, it is a complex matter. Both believe that the Church will not fail and that one should fight for the truth with all one’s heart by attending carefully to the Scriptures and to the faith one has inherited. Neither believes that God’s gift of the possibility of advancing in knowledge is a matter of changing the faith in order to take account of changing times; it is, rather, a gift whose acceptance involves embracing disciplines of attentiveness to that which we have been given and taught, and practices of careful theological reasoning within the body of Christ.
Let us now leave the early Church and turn to the last two centuries. Modern discussions of doctrinal development have taken place against the background, first, of the growing secular belief in inevitable change and progress that was so important in the nineteenth century, and then, second, and in our own day, against a growing sense that modern historical consciousness renders somehow obvious a certain cultural relativism—ideas change and shift across time and cultural space, and so discontinuity and radical change is simply the stuff of human life. Against such backgrounds, it is not at all surprising that the question of doctrinal development became extremely controversial—allowing certain forms of development might seem to push us down a slippery slope that would undermine the dependability of the Church’s teaching. And thus, modern discussions of this issue should be seen as part of a wider crisis of authority not so much in the Church as in modern Western culture as a whole. However, one of the things that theologians need to do constantly is to put down the newspaper and look up at the icons of the saints, look away from the moment and towards the long history of which we are part.
I am going to spend a lot of time with the famous account of St. John Henry Newman, both because I think it remains a fruitful vision for our times, and because of the interesting parallels that I think we can see back across the centuries. For Newman, it is of the very nature of human existence that ideas mature:
It will often happen, perhaps from the nature of things, that it is impossible to master and express an idea in a short space of time. . . . How many men are burdened with an idea, which haunts them through a great part of their lives, and of which only at length, with much trouble, do they dispossess themselves? I suppose most of us have felt at times the irritation, and that for a long period, of thoughts and views which we felt, and felt to be true, only dimly showing themselves, or flitting before us; which at length we understood must not be forced, but must have their way, and would, if it were so ordered, come to light in their own time.
This vision of the human mind slowly coming to grasp an idea and its dimensions, an idea in all its depths, is presented in a deeply personal manner, but it is very close to that which we saw in Gregory Nazianzus.
It is something like this that Newman saw at work in the growth of Christianity. Christian teaching is, for Newman, at its heart, an idea, or a collection of ideas and judgements, that lives in the mind and heart. Newman argues that when we read, “This is eternal life, that they may know you, the only true God, and Jesus Christ whom you have sent” (John 17:3), the knowledge of which John speaks is the fundamental idea given to us in faith. He writes thus:
Knowledge is the possession of those living ideas of sacred things, from which alone change of heart or conduct can proceed. This awful vision is what Scripture seems to designate by the phrases “Christ in us,” “Christ dwelling in us by faith,” . . . . And though it is faint and doubtful in some minds, and distinct in others, as some remote object in the twilight or in the day, this arises from the circumstances of the particular mind, and does not interfere with the perfection of the gift itself.
So, we are given as a gift an idea by Christ dwelling in us, and that idea lives within us and in those with intellectual gifts is drawn out slowly into many propositions and statements. But just as this is so in the individual Christian, so also it is true in the Church.
Newman, however, thinks also—just like Gregory and Vincent—that one significant difference between the life of the individual and the Church as a whole is that the Church as a whole speaks, and does so reliably as a guide for us in our own personal struggles to understand and interpret the faith we have been given.
To understand more fully what Newman offers us, we need to turn away from Newman’s direct discussions of development and think about how he envisages human decision making. Newman emphasizes that we reason on the basis of assumptions and authorities far more commonly than we work purely in logical terms:
However full and however precise our producible grounds may be, however systematic our method, however clear and tangible our evidence, yet when our argument is traced down to its simple elements, there must ever be something assumed ultimately which is incapable of proof, and without which our conclusion will be as illogical as Faith is apt to seem to men of the world.
We like to think that we reason by saying to ourselves, supposing that A and B are so then C seems to follow. In fact, the reality is far more complex. Especially in arguments that pertain to the important realities of life, we always find ourselves enmeshed, for Newman, in incalculable webs of assumption and antecedent probability on the basis of which we reason.
In The Grammar of Assent, Newman gives many examples of the phenomenon. Let us take one he does not give. Lewis decides that he needs to eat more healthily and that he’s going to change his breakfast cereal. So, Lewis goes to the grocery store and looks at the endless packets of cereal on display and opts for one that says it has more fiber and less sugar. This seems like a logical decision. But, as Newman would point out, my decision is actually founded on a host of assumptions that I cannot test. I assume that the cereal packets identify accurately what is in them, I accept on trust the frequent message that sugar is bad for me, I accept also the message that more fiber is good for me. These may be excellent assumptions, but I can hardly test them all. So, it is not that we do not reason, it is that reasoning is no escape from the webs of assumed probability within which we think. In all this, Newman does not think he is showing us that we know less than we thought, but that virtually all significant certainties that human beings come to are of this form, they are based on what he calls “antecedent probability.” This vision of the importance of inference will help us understand the character of theological reasoning in the Church over time.
How then may we imagine theological reasoning, especially the theological reasoning of the Church? Consider the definition of Mary’s Immaculate Conception. For some of those who can countenance doctrinal development as the logical extrapolation of the implicit from the already explicit, clear scriptural warrant is required. Could we say, for example, that because Mary is “full of grace,” it follows as a matter of logic that she cannot have been subject to the normal consequences of conception and birth as a human being? From Newman’s perspective this is a self-deceptive argument. Someone who makes it, for example, assumes that the phrase is appropriately subject to this sort of parsing—but that is an assumption based on a wide range of prior and not logically demonstrable commitments about scripture and its interpretation. There may be nothing wrong with those commitments per se, but their existence needs to be acknowledged.
And so, what we should look for in the development of the Church’s life and belief is a growth that reflects these realities of life. God has given us these minds and these modes of reasoning, and it is through them that the Church is led to grow in the way that it has. There is much here that reflects a commonality between Newman’s mode of reasoning and that of Gregory and Vincentius. For all three authors, God’s ordering of revelation’s unfolding follows an order that is appropriate to the nature of created and fallen humanity, it has beauty and fittingness, it is something on which we may and should dwell. Because this is an unfolding under the guidance of the Spirit, in watching it we watch God at work. The Church makes judgements on the basis of a world of assumptions developed over centuries, often in contexts where theologians have disagreed at length, but the reasons she gives still have a suitability and foundation that human beings can grasp, even as other possibilities were available. But, like Gregory Nazianzus and Vincentius, Newman thinks that the Church is aided in its discernment by the Spirit’s work, activating the “idea” given it by its Lord so that the meaning of the faith is preserved.
In An Essay on the Development of Christian Doctrine Newman, outlines seven “notes” of authentic doctrinal development. We do not need to consider them in detail here, but we should be struck by the extent to which he is always talking about what has happened; Newman is not laying out for us a scheme that enables us to predict where the Church might go next, he is helping us be at peace with the Church as it now is. He is teaching us, one might say, to think with the Church, to attend to and appreciate the complexities and strange paths of its development. At the very heart of these “notes” is a concern to show how developments of doctrine, while not the only logical course that might have been taken, are fitting developments given what has gone before, fitting growths in knowledge, drawn out under the Spirit’s guidance. Once again, as with our early Christian examples, any useful discussion of doctrinal development must go hand in hand with a clear sense of the habits and dispositions that we need to cultivate within ourselves. It is no accident that Newman’s “Fifteenth University Sermon,” which focuses on the question of doctrinal development, begins by citing Mary’s careful pondering in her heart of all that she has witnessed.
Finally, we can come to a fundamental question: does the idea of doctrinal development mean that we know more than the apostles? I hope it will not be too controversial if I say that were we to meet one of the apostles and ask them to set out their faith, we would not expect a recitation of the Nicene Creed. We would not expect this simply because we have their words recorded reliably for us in the New Testament, and we have no evidence that such a formula was somehow kept hidden until it was promulgated in the fourth century. So far, so good. But the question is not yet answered; again, Newman will point us to a useful answer.
The apostles were imbued in the images and stories of the Scriptures and their encounter with Christ before and after his resurrection was molded by this symbolic universe. Those to whom the risen Christ appeared—the apostles in the upper room, those on the road to Emmaus, or Paul on the road to Damascus, for example—were at first shocked, stunned, relieved, surprised, and uncomprehending. The faith that grew in them was a gift, part of the God’s salvific economy; just as Christ has come in the fullness of time, so the apostles were given the gift of faith that they might be able to witness to Christ’s resurrection and preach the meaning of his work. The “idea” of Christianity lived in them in full force through the Spirit’s gift, but they were human, and in God’s economy the unfolding that was to come was to be rooted in the symbolic world of Israel’s scriptures, and in their gradual reconfiguration of that world, that language. The gift they had received worked in different ways to different ends, to the unfolding of different features of the “idea” in different circumstances; in some, it enabled a preaching, such as that of Peter at Pentecost; in Paul, it occasioned also his challenge to the community in Jerusalem; in some, it enabled a witness in the form of martyrdom. In all these different ways the Church’s understanding of what the faith was grew and deepened. Something like this picture is hallowed by the Second Vatican Council’s document on revelation, Dei Verbum, when it speaks of revelation as Christ’s person shaping the apostles both through word and through the impact of his life, and their authoritative response to revelation coming in the form of lives that testified, and of preaching. But we need not expect the apostles to have been able to recite the Creed or know all the language of the Catechism; they had the fullness of revealed knowledge, and the language in which they expressed their knowledge was the language God had intended.
The apostles passed from the stage and the growing life of the faith and the emergent text of the Scriptures was bequeathed to the Church. What follows subsequently is an unfolding of the many dimensions of that life and text, under the guidance of the Spirit. But there is an important difference. The apostles, through the work of Son and Spirit, fill out the body of revelation for us. The Church is subsequently guided such that it can judge and define, that it can interpret reliably whether a particular language interprets or does not interpret well the Christian idea, but the Christian community after the apostles is always poised between the divine gift of faith and the working of the human mind. Through the work of Christ and the Spirit, the body of Christ is prompted and drawn on by grace—exemplary lives, acts of repentance, a variety of theological insights are offered to us down the years, but the community of the Church is full of human lives and human wills struggling to live and think in the light of the gift of faith. In Christ and the apostles, God’s Word is spoken, in the life of the Church a divinely ordered response is given, but given over time as the Church slowly grows in knowledge and is guided to speak authoritatively and more fully of the mystery given in revelation.
But the question has not yet been answered: “do we know more than the apostles?” I think we need to give more than one answer simultaneously. In the most important sense, of course not. The life of faith working in us is the very same divine gift given at Pentecost, and it is faithfulness to that gift that they and we are saved. And yet from another angle, we can also say yes, there are things that we can say that the apostles did not; we can say the Nicene Creed, we can say in simple form, “the Spirit is God.” We have both such clear statements and what Newman called “a scientific vocabulary,” which has grown in the Church to discuss doctrine, and this has given us over the centuries a memoria technica, “condensing the tradition of a thousand questions and answers.”
But—and the “but” is vital—the gift of such articulate expressed knowledge is always an opportunity for us to contribute to the slow restoration of the human race; were we to assume that we had by ourselves achieved something in the realm of speculative knowledge, then that knowledge would be a curse. Perhaps the gift of further expressed knowledge should be seen as parallel to the growth of the Church’s spiritual traditions. It would be utterly daft to think that this means that the Christians of an age before the Ignatian Institutes, before the Franciscans, before the emergence of icons, somehow were less able to grow in knowledge of Christ; but at the same time, we can also celebrate the flowering of these traditions as a gift suitable for the Church in its various ages. So, how we answer the question, “do we know more than the apostles?” is one that should inevitably draw us to ask about the dispositions that we should cultivate when we reflect on what we know or do not know. We must struggle to know what we know, and yet, see that as gift, we must struggle to hold in tension the Spirit’s leading of us into all truth with a recognition that our faith seems always to lack the depths of Peter and Paul.
The value of Newman’s account of doctrinal development, and the reason that much of it can still form a foundation for our thoughts today, is that it is not a merely defensive notion, designed to account for differences in teaching over time that have only become more obvious to modern historical consciousness. It is, rather, part of an ecclesiological and soteriological vision, a vision of God speaking through the Incarnate Word, and the through the gift given to the apostles, and then allowing the human answer to that word to flower in the time of the Church.
Editorial Note: This essay has been developed from a much longer talk for the Thomistic Institute given in Toronto. I would like to thank Fr. Andrew Summerson and Liam Farrer for hosting the event.
 Gregory Nazianzus, Oration 31. 26–7. Translated in St. Gregory of Nazianzus, On God and Christ. The Five Theological Orations and Two Letters to Cledonius, tr. by Frederick Williams and Lionel Wickham (Crestwood NY: St Vladimir’s Seminary Press, 2002), 137–8. It is sometimes argued that Gregory should not be read as parallel to modern western theories of development because he sees the fullness of knowledge in the apostles. I think this a misreading of the passage; he is merely showing that even in the apostles knowledge of Christ had to grow; so much more did knowledge of the Spirit need to grow in the Church.
 Thomas Guarino, Vincent of Lerins and the Development of Christian Doctrine (Grand Rapids MI: Baker, 2013).
 And this, among other reasons, is why Catholic theologians who sustain a vision of doctrinal development should also see Scripture as, through the action of its divine author, sustaining multiple readings, as possessing depths that we continue to plumb. See, e.g., John Henry Cardinal Newman, An Essay on the Development of Christian Doctrine, foreword by Ian Ker (Notre Dame IN: University of Notre Dame Press, 1989), 58–60.
 For a deeper introduction to Vincentius, see Thomas Guarino’s Vincent of Lerins and the shorter article by the same author, “St Vincent of Lerins and the Development of Christian Doctrine,” Logos: A Journal of Catholic Thought and Culture 17 (2014): 103–117.
 Vincentius, Commonitorium, 23. An English translation may be found in Nicene and Post-Nicene Fathers, second series, vol. v/2, ed. Philip Schaff and Henry Wace (Grand Rapids, MI: Eerdmans, 1978), 131–56. This translation is also easily available online.
 I have suggested that at the heart of the vision of orthodox Trinitarian belief that emerged in the fourth century was a particular “culture” of discernment, and attention to the divine mystery. See Nicaea and Its Legacy (Oxford: Oxford University Press, 2004), chapters 11–13.
 John Henry Newman, Fifteen Sermons Preached Before the University of Oxford, ed. J.D. Earnest and G. Tracey (Oxford: Oxford University Press, 2006), 218–9. The text is also available at Newmanreader.org (accessed 11 June 2023).
 Newman, Fifteen Sermons, 223–4.
 There is also here in Newman a remarkable balance between insistence on the necessity of the Church speaking and guiding us as the Christian idea unfolds, and the fundamental principle that whatever terms the Church defines in the Spirit are a priori transcended by the mystery of God. Thus, he writes, “The Catholic dogmas are, after all, but symbols of a Divine fact, which, far from being compassed by those very propositions, would not be exhausted, nor fathomed, by a thousand.”
 Newman, Fifteen Sermons, 149–50 (Sermon 11). See also the extensive discussion in John Henry Newman, An Essay in Aid of a Grammar of Assent, ed. Ian Kerr (Oxford: Clarendon Press, 1985), chapter 8.
 For a very helpful discussion of the ways in which Newman’s account is related to such alternate accounts of doctrinal development, see Andrew Meszaros, “John Henry Newman and the Thomistic Tradition: Convergences in Contribution to Development Theory,” Nova et Vetera 19 (2021): 423–468. Also of great interest in this regard is C. Michael Shea, Newman’s Early Roman Catholic Legacy 1845–54 (Oxford: Oxford University Press, 2017).
 For Newman’s argument that it is in the nature of revelation there is an antecedent probability that there must be an authority to make decisions about its meaning, see An Essay on the Development of Christian Doctrine, 78ff.
 Newman, An Essay on the Development of Christian Doctrine, chapters 6–11.
 A particularly important source for these paragraphs is Newman’s letter or small treatise addressed to Fr. Stanislaus Flanagan of Feb 15, 1868, available in J. Derek Holmes, ed., The Theological Papers of John Henry Newman on Biblical Inspiration and Infallibility (Oxford: Clarendon Press, 1979), 151–160.
 As Newman writes in “Letter to Flanagan,” 158: “The apostles did not merely know the Apostles Creed; what knowledge could be more jejune, unless the meaning of each separate word of it was known in fullness? They must know all and more than all about the word “Son of God,” which the Church has enunciated since their time. And so of every article, and portion of an article. What then is meant by the Depositum [the deposit of faith]? Is it a list of articles that can be numbered? No, it is a large philosophy; all parts of which are connected together. . . . Thus the apostles had the fullness of revealed knowledge, a fullness which they could as little realize to themselves, as the human mind, as such, can have all its thoughts present before it at once.”
 The language of “response” here is taken from Joseph Ratzinger, Principles of Catholic Theology, trans. Sr. Mary Frances McCarthy SND (San Francisco CA: Ignatius Press, 1987), 147ff.
 Newman, “Letter to Flanagan,” 157: “Such a scientific apparatus has its evils; for common minds, instead of throwing themselves into the genius and animus of the philosophy, will make the technology the beginning and end of their study; and will be formalists, pedants, bigots, and will be as little made philosophers by their verbal knowledge, as boys can swim because they have corks or run because they have belts.”