Before Infallibility: What the Medieval Canonists Actually Believed

In 1870 the First Vatican Council defined the doctrine that the pope can teach infallibly under certain conditions when speaking on matters of faith and morals. For many Catholics the decree was understood as a formal confirmation of a belief that had always existed in the Church. Yet when historians began to examine the legal and theological sources of the medieval Church, the picture proved far more complicated. In his influential study The Origins of Papal Infallibility, 1150–1350, the historian Brian Tierney explored the writings of medieval canonists and theologians and discovered that the question of papal authority; and even the possibility of papal error, was debated far more openly than modern readers might expect.

During the debates leading up to the First Vatican Council in 1870, supporters and critics of papal infallibility agreed on one thing: declaring the pope infallible would greatly strengthen papal authority. Ultramontane writers celebrated this openly, while critics warned that it would create a form of ecclesiastical absolutism.

But historian Brian Tierney points out an unexpected problem. The ideas of infallibility and sovereignty do not actually fit together very well. A sovereign ruler must be free to change the policies of previous rulers. Yet infallible teachings are supposed to be permanent and irreformable. If earlier popes issued infallible decrees, later popes would be permanently bound by them.

This creates a dilemma. If every past papal teaching on faith and morals were truly infallible, the Church today would be tied to many positions shaped by the circumstances of earlier centuries. To avoid this problem, modern theologians have developed increasingly complex rules about when a pope is actually speaking infallibly. The result is that, although the doctrine was defined in 1870, there is still disagreement about which papal statements qualify as infallible.

Since the definition of papal infallibility at the First Vatican Council in 1870, the practical scope of the doctrine has remained surprisingly uncertain. In practice, the only papal definition widely regarded as clearly infallible since that council is the proclamation of the Assumption of Mary by Pope Pius XII in 1950. Yet a broader difficulty immediately arises. If papal teachings are truly irreformable, then later popes would appear to be permanently bound by a vast body of earlier decrees that addressed the political, moral, and theological problems of very different historical contexts.

Modern Catholic theologians have attempted to address this tension in several ways. Some have limited the doctrine by arguing that only a very small number of papal statements qualify as infallible. Others have emphasized the authority of the pope’s ordinary teaching office, a theme developed by Pius XII in his encyclical Humani Generis. Yet these approaches introduce further complications, since papal teachings from different periods sometimes appear to conflict—particularly on issues such as religious toleration.

As a result, discussions of infallibility often depend on careful distinctions about when a pope is truly speaking ex cathedra and which teachings must be considered permanently binding. By the time of the Second Vatican Council, the doctrine had become surrounded by a complex network of interpretations and qualifications.

Rather than attempting to resolve these modern theological debates, historians such as Brian Tierney have approached the issue from a different angle. Instead of asking how the doctrine should be interpreted today, they ask a more fundamental historical question: how did earlier generations of canonists and theologians understand the authority—and possible fallibility—of the pope?

To explore this question, Tierney examines the origins of the ideas that later culminated in the doctrine of papal infallibility. His study focuses particularly on the writings of medieval canon lawyers between roughly 1150 and 1250, the period when systematic reflection on papal authority first began to take shape.

Among the key questions are these: What is the source of revealed truth; Scripture alone, or Scripture together with apostolic Tradition? Under what circumstances can the pope speak infallibly on matters of faith and morals? Is the pope’s teaching authority part of the primacy traditionally associated with the apostle Peter? Can the decisions of a pope be appealed to a general council as to a higher authority? And finally, when the pope makes a definitive doctrinal statement, is that decree permanently irreformable?

These issues were not invented in the nineteenth century. Their roots lie deep in the legal and theological debates of the medieval Church. By examining how early canonists approached these questions, Tierney hopes to shed light on the historical foundations; or possible absence; of the doctrine that was later defined in 1870.

Questions

If a pope is supreme, how can he be bound by the irreformable decrees of earlier popes?

If earlier canonists believed a pope could fall into heresy, what exactly is supposed to have “developed” into infallibility?

If infallibility is real, why is there no clear and agreed list of infallible papal statements before 1870?

If the Church needs an infallible pope to avoid uncertainty, who removes the uncertainty about which papal acts are infallible?

Early Christian writers frequently appealed to the authority of the Church’s Tradition when interpreting Scripture. Figures such as Augustine of Hippo and Vincent of Lérins emphasized that the true meaning of the faith could be recognized through what the universal Church had consistently believed. In this sense, Tradition served as a guide to understanding Scripture. Yet the early Fathers generally did not treat Tradition as a separate source of divine revelation alongside Scripture. Rather, Scripture and the teaching of the Church were understood as deeply interconnected, with the Church interpreting and preserving the truth contained in the biblical texts.

This outlook largely continued in the medieval period. Twelfth-century theologians and canon lawyers assumed that the essential truths of Christian faith were already contained in Scripture. Traditions outside Scripture; such as liturgical practices or church customs; were acknowledged, but they were not usually treated as independent revelations of new doctrines. The Church’s role was primarily to interpret and transmit the meaning of Scripture to each generation.

Some modern scholars have argued that medieval canon lawyers gradually introduced a different view, in which Tradition became an independent source of revelation and papal decrees acquired an authority equal to or even greater than Scripture. However, a closer look at the medieval legal texts suggests otherwise. The canonists did treat Scripture and Tradition as important foundations of church law, but they still maintained a clear distinction between divine truths revealed by God and human laws created by the Church. In matters of faith, papal authority was not understood as standing above Scripture but as operating within the framework of Scriptural revelation itself.

One of the most important medieval texts for understanding church law is the Decretum Gratiani, compiled in the twelfth century by the canonist Gratian. The very opening lines of this work reveal something crucial about how medieval canonists understood authority in the Church.

Gratian explained that human society is governed by two kinds of law: natural law and human law. Natural law, he said, is expressed in Scripture itself; especially in the moral teaching of the Gospel, such as the “golden rule.” Human laws, by contrast, include the customs and statutes created by societies and institutions, including the Church.

This distinction had an important consequence. Because church laws were considered part of human law, they were not absolute. Gratian stated explicitly that if any human law; whether secular or ecclesiastical, contradicted natural law, it must be rejected. In other words, the authority of church legislation was understood to be subordinate to the moral principles revealed in Scripture.

This framework makes something clear about medieval thought: canon lawyers did not view the Church; or even the papacy, as possessing unlimited authority to define new truths. The ultimate standard remained the revealed principles contained in Scripture. Church laws and papal decrees could regulate the life of the Church, but they were still subject to a higher rule.

In the Decretum Gratiani, the canonist Gratian carefully arranged different kinds of authority within church law. Natural law and Scripture stood at the highest level. Beneath them were the laws created by the Church itself, including statutes and customs. While statutes carried greater authority than customs, Gratian acknowledged that certain customs; especially those that could be traced back to apostolic times, deserved respect and continuity.

To illustrate this point he cited a passage from Basil of Caesarea which explained that some practices of the Church came directly from Scripture while others had been handed down through apostolic tradition. Gratian used this example not to argue that Tradition was a separate source of divine revelation, but simply to show that long-established customs should be preserved when they did not contradict higher laws.

In this framework, Tradition was not treated as an independent body of revealed doctrine alongside Scripture. Instead, it was understood largely as inherited practice within the Church’s legal and liturgical life. Medieval canonists generally followed Gratian in this interpretation. Rather than appealing to Tradition as a separate source of new teachings, they tended to assume that the essential truths of the faith were already contained in Scripture, with the Church responsible for preserving and interpreting that revelation over time.

Questions:

When a doctrine appears only many centuries later, should it be called Tradition; or reinterpretation of the past?

If Scripture contains the original revelation of the faith, what authority can legitimately stand above it?

If church authority interprets Scripture, who judges whether that interpretation remains faithful to the text?

If medieval canonists believed that church laws must submit to higher moral principles derived from Scripture, what does that imply about the limits of papal authority?Can an authority be considered absolute if it remains subject to a higher rule?

The medieval canonists did attribute great authority to the pope, often describing him as the supreme judge and legislator of the Church. Yet this authority was not understood as the power to create new divine revelations. The primacy of the papacy was believed to rest on the authority given by Christ in the New Testament, while later traditions and councils simply affirmed or clarified that original foundation. Even when canon lawyers used extravagant language about papal power, they usually meant the pope’s authority to govern and judge disputes within the Church; not the power to introduce new doctrines apart from Scripture.

Some medieval canonists did use remarkably strong language when describing the authority of the pope. In certain legal texts the pope is said to possess the “plenitude of power,” to stand above all human law, and even to act as God’s representative on earth. At first glance such claims might appear to place papal authority on a level equal to divine revelation itself. But a closer examination of their context shows that something quite different was intended.

The key to understanding these statements lies in the legal framework in which they were written. Medieval canon law was deeply influenced by Roman law, which treated the sovereign ruler as possessing ultimate legislative authority within the realm of human law. Roman jurists explained that laws had to change as human circumstances changed, since “nature continually produces new forms.” Medieval canonists applied this principle to the governance of the Church. The pope, as the supreme legislator of the Church, had the authority to create new legal rules, modify earlier ones, or grant dispensations from existing regulations when new situations arose.

This authority, however, operated only within the sphere of human or positive law; the body of regulations created to organize and govern the life of the Church. It did not extend to the realm of divine revelation. Even the popes themselves acknowledged this distinction. While they claimed the authority to alter human laws issued by earlier popes, they did not claim the ability to change the truths of faith grounded in Scripture. Indeed, one pope, Innocent III, famously declared that he stood “between God and man,” even though the New Testament proclaims that Christ’s sacrifice tore the veil and opened direct access to God through Him, he could still be judged by the Church if he were to fall into error in matters of faith.

This distinction is important because it corrects a common misunderstanding. When modern readers encounter the bold language of medieval canonists about papal authority, it is easy to assume that they were claiming for the pope a kind of unlimited theological supremacy. But the context shows that their claims were usually legal rather than doctrinal. The canonists were borrowing categories from Roman law in order to describe the pope’s authority as the supreme legislator within the system of canon law.

Once this legal background is understood, the rhetoric becomes far less surprising. A sovereign legislator in Roman law could create new statutes, modify earlier laws, or dispense from them when circumstances required. Medieval canonists applied this model to the governance of the Church. In that sense the pope could “make something from nothing” by creating a new legal rule or resolving a case that had not previously been addressed by law. Yet this authority operated within the sphere of human legislation. It did not extend to the creation of new articles of faith or new revelations.

Recognizing this distinction helps clarify the real limits that medieval canonists placed on papal authority. Even while they described the pope as the highest judge and legislator in the Church, they still assumed that the truths of faith were grounded in Scripture and that those truths lay beyond the reach of papal legislation. In other words, the pope could shape the legal order of the Church, but he could not redefine the foundations of the faith itself.

Medieval discussions about the pope’s ability to “dispense from Scripture” must be understood carefully. Canonists did not mean that the pope could override divine revelation or create new truths of faith. Rather, they were dealing with a more practical question: whether certain biblical commands were meant to be observed literally for all time, or whether they were disciplinary rules that could change under different circumstances.

When questions arose about how particular biblical texts should be applied within the life of the Church, it was natural that the authority of the Roman see would be consulted to determine whether a given command was permanent or disciplinary.

This issue became particularly visible in debates about ecclesiastical discipline. One famous controversy concerned whether the pope could allow a man who had been married twice and widowed twice to be ordained as a bishop, even though a passage from the writings of St. Paul states that a bishop should be “the husband of one wife.” Canonists debated whether the pope had the authority to grant such a dispensation. Yet even those who allowed for the possibility insisted that such a decision would lie at the extreme limits of papal authority. The question concerned church discipline, not the substance of Christian belief.

The debate is especially revealing because the prohibition in question came directly from the Apostle Paul. Since medieval canonists often taught that the pope inherited the authority of Peter; who was regarded as the head of the Church and therefore greater in rank than Paul, one might suppose that the pope could simply override a Pauline command. In reality, however, the canonists placed clear limits on papal power. They agreed that while the pope might in rare cases modify disciplinary rules derived from Scripture, he could never alter matters of faith.

This principle appears repeatedly in the standard legal commentaries of the Middle Ages. Canonists consistently maintained that the pope might dispense from certain scriptural rules in matters of discipline, but not in doctrines of faith. The teachings of the New Testament; whether spoken by Christ himself or written by the apostles; remained binding on all popes. Papal authority therefore operated within the framework of scriptural revelation rather than above it.

Seen in this light, the medieval doctrine of papal sovereignty did not make the pope a second source of divine revelation or the bearer of a Tradition that could rival Scripture. The canonists’ strong language about papal power must be understood within the context of church reform in the eleventh and twelfth centuries. Reformers faced a Church weighed down by centuries of entrenched customs, many of which were corrupt or inconsistent with the ideals of the Gospel. To reform the Church required an authority capable of overriding these inherited practices.

The rediscovery of Roman legal ideas about sovereignty provided such a framework. In Roman law the sovereign ruler was not bound by earlier laws enacted by inferior authorities, nor even by laws enacted by previous rulers. This concept allowed canonists to describe the pope as possessing the legislative authority necessary to reform church discipline and establish new legal regulations when circumstances required.

Yet this sovereignty operated only within the sphere of human law. The pope could change ecclesiastical regulations, grant dispensations, and resolve disputes about discipline. But the truths of faith grounded in Scripture remained beyond the reach of papal legislation. In the medieval legal imagination, divine revelation formed the permanent foundation of the Church, while papal authority governed the changing legal structures built upon that foundation.

If papal sovereignty was modeled on Roman legal ideas about the power to modify human laws, does that analogy really support the claim that a pope can pronounce infallible teachings about divine revelation?

Brian Tierney points out that early canon lawyers in the twelfth century; the Decretists, who wrote the first commentaries on Gratian’s Decretum; did not interpret the biblical foundations of papal authority in the same way that later medieval theologians did. In particular, they did not read Christ’s prayer for Peter in Luke 22:32 as a promise that the pope would be doctrinally infallible.

Luke 22:32: Ego autem rogavi pro te ut non deficiat fides tua

“But I have prayed for you that your faith may not fail.”

Later defenders of papal infallibility often argued that this statement guaranteed that Peter’s faith, and therefore the faith of his successors in the papacy, could never fail when teaching the Church. But Tierney observes that the Decretists knew nothing of this interpretation. Their reading of the passage followed the older tradition of the Church Fathers.

A representative example comes from the canonist Huguccio. He explains that Christ’s words do not mean that Peter was incapable of failure. Peter’s faith could falter temporarily; as shown by his denial of Christ during the Passion; but it would not collapse permanently. Christ’s prayer ensured that Peter would ultimately return to faith. The promise therefore concerns Peter’s eventual perseverance rather than any kind of immunity from error.

Huguccio also presents another interpretation common in patristic exegesis. In this reading Peter stands as a figure representing the Church itself. The assurance that “your faith will not fail” refers not to Peter individually but to the faith of the universal Church. Individual believers, including church leaders, might fall into error, but the Church as a whole will never lose the true faith before the end of time.

Tierney’s point is that, for these early canonists, the passage did not grant Peter; and certainly not later popes, an infallible teaching authority. Instead it was understood either as a promise of Peter’s restoration after failure or as a guarantee that the Church collectively would remain faithful. The idea that this verse establishes papal infallibility is therefore a later theological development, not something assumed in the earliest canon law tradition.

Medieval canonists were familiar with the biblical language of the “keys” and accepted that Christ’s promise of the keys to Peter signified a special authority in the Church. In their view, the key of power referred to Peter’s governing authority; his jurisdiction as head of the Church. This was the basis on which canonists justified the pope’s role as the Church’s highest judge. Peter, and by extension the pope, possessed the authority to bind and loose, to admit or exclude, and to settle disputes within the Christian community.

At the same time, medieval theology also spoke of another key: the key of knowledge (clavis scientiae). The phrase itself comes from Scripture, where Christ rebukes the lawyers for taking away the “key of knowledge” (Luke 11:52). Early commentators such as Bede connected this passage with Christ’s promise to Peter of the “keys of the kingdom of heaven.” From this association arose the common idea that Peter had received two keys: one of power and one of knowledge. This terminology was repeated by major medieval authorities, including Hrabanus Maurus, Peter Lombard, and Gratian. By the twelfth century it was firmly embedded in both theology and canon law.

Yet an important fact stands out. Although the canonists accepted that Peter possessed both keys, they did not interpret the key of knowledge as granting the pope an infallible teaching authority. The possibility was logically available. If the key of power established the pope’s supreme authority to govern the Church, it would have been easy to argue that the key of knowledge established his supreme authority to teach without error. But the medieval canonists never developed the idea in this direction.

Gratian’s discussion of the two keys shows why. He introduced the distinction in order to clarify the difference between theological interpretation and judicial authority. In explaining Scripture, he suggested, great theologians such as Augustine or Jerome might even surpass the pope in learning and insight. But in deciding legal disputes or issuing binding judgments within the Church, the pope held the final authority. Knowledge and power therefore functioned differently: theological understanding belonged to scholars and teachers, while the authority to govern and judge belonged to the papal office.

This raises an obvious question.

If the pope’s key of knowledge did not make him the Church’s most reliable interpreter of Scripture, how could it later come to be understood as guaranteeing an infallible teaching office?

Gratian himself seemed comfortable admitting that other theologians could excel the pope in knowledge. That admission sits uneasily beside later claims that the pope’s doctrinal judgments are uniquely protected from error.

Some Decretists realized that Gratian’s neat separation between theology and law could not always be maintained. Papal judgments; especially in cases of heresy, could have doctrinal consequences. In such cases they acknowledged that the pope’s official ruling carried binding authority. Yet even here they did not claim that the pope possessed an inherent immunity from error. Instead they distinguished between the pope acting as a private theologian and the pope acting in his official judicial capacity. One canonist illustrated the point by suggesting that if the pope and Augustine each wrote theological treatises privately, Augustine’s work might well be the better guide. But if the pope issued an official judgment on a matter of faith, that decision would bind the Church.

Even then, caution remained. Huguccio warned that a pope should not depart lightly from the teaching of the Church Fathers when issuing such judgments. If the pope truly possessed an infallible “key of knowledge,” why would such restraint be necessary? Why would his authority need to be anchored so firmly to earlier tradition?

What emerges from these discussions is a picture of papal authority quite different from the one that would later dominate Catholic theology. Twelfth-century canonists strongly affirmed the pope’s governing authority in the Church. But they did not transform the language of the “key of knowledge” into a guarantee of doctrinal inerrancy. Their silence on this point is historically significant. The scriptural texts and patristic sources were already available to them. If papal infallibility followed naturally from those sources, why did these early canonists; who were deeply concerned with defining papal authority; not draw that conclusion?

The most plausible answer is that the idea had not yet taken shape. For the Decretists, authority in the Church did not automatically imply infallibility. That connection would only emerge later, when the meaning attached to the familiar language of the “keys” began to change.

Gratian’s discussion of the keys makes clear that, in the early canon law tradition, the special authority of the pope did not come from a supposed “key of knowledge,” but from the key of power. In other words, what distinguished the pope was not a unique capacity to teach the truth without error, but his position as the Church’s supreme judge. The authority attributed to him in matters of faith therefore functioned juridically rather than intellectually. When doctrinal questions arose in the context of disputes or cases, the pope could issue a binding judgment. But this did not mean that he was regarded as an infallible theologian.

Huguccio makes this distinction particularly clear. He considered the case of a pope who happened also to be a learned scholar. If such a pope expressed a theological opinion in debate with another theologian, his status as pope did not make his interpretation automatically more reliable. In matters of scholarship he stood on the same footing as other learned teachers. Yet if that same pope issued a decision as pope; settling a case or giving a formal ruling; then the Church was obliged to accept the judgment because of his jurisdictional authority.

This distinction reveals how differently medieval canonists understood papal authority compared with later theories of papal infallibility. The pope’s authority lay primarily in his role as judge within the Church’s legal order. It was not based on the assumption that he possessed a uniquely protected teaching office. If a pope happened to make an erroneous judgment in a case touching on faith, canonists generally assumed that the mistake would eventually be corrected; either by the pope himself or by one of his successors. Historical examples, such as the correction of earlier papal errors, reinforced this expectation. The security of the Church’s faith therefore rested not on the impossibility of papal error, but on the belief that the Church as a whole would not be permanently led astray.

Significantly, none of the Decretists used Gratian’s discussion of the “key of knowledge” to develop a theory of papal magisterium, still less an infallible magisterium. In fact, they seem not to have thought in terms of a public teaching office of the pope established through the power of the keys. The concept that the pope possessed a divinely guaranteed doctrinal authority; distinct from and superior to other teachers; simply does not appear in their writings.

This raises an important historical question. If the language of the keys and the relevant biblical texts were already central to twelfth-century theology and canon law, why did the canonists not interpret them as establishing an infallible papal teaching authority? These were scholars deeply invested in defining papal authority, yet they stopped short of making that claim. Their silence suggests that the later doctrine of papal infallibility did not arise naturally from the earlier canonical tradition but represented a later theological development, one that gradually transformed the meaning of concepts that originally served a very different purpose.

Early canon lawyers (the Decretists) discussed the authority of councils and the pope mainly by interpreting two passages in Gratian’s Decretum. One passage quotes a letter from Pope Gregory, later known as “Gregory the Great,” a designation that reflects later tradition rather than the humility expected in Christian leadership, stating that the first four general councils should be honored “like the four Gospels” because they had been accepted by the universal agreement of the Church. Another passage recorded Gratian’s own statement that the Roman Church gives authority to the canons but is not itself bound by them.

Once canonists began writing detailed commentaries on Gratian around the middle of the twelfth century, they quickly realized that this second statement could not be taken too literally. It was obvious that the pope could not simply overturn the doctrinal decisions of the great early councils such as Nicaea or Chalcedon. These councils had defined fundamental teachings about the Trinity and the person of Christ, and such teachings were not regarded as changeable. The canonists believed that these dogmatic definitions were fixed because they were grounded in the truth of Scripture.

At the same time, the early councils had also issued many rules about church discipline; regulations dealing with practical matters of church life. These disciplinary decisions, the canonists argued, could be modified if circumstances required it. In other words, a pope could alter the practical regulations issued by councils, but he could not alter their teachings on matters of faith.

From this distinction some canonists drew an important conclusion. When questions of doctrine were involved, a general council held an authority that was greater than that of a single pope. This idea was expressed clearly by the canonist Johannes Teutonicus, who wrote that when a matter of faith was at stake the pope was obliged to consult a council of bishops, and in such cases the authority of the council surpassed that of the pope acting alone.

The canonists based this view partly on Gregory the Great’s statement that the first four councils deserved special reverence. However, they did not interpret Gregory as claiming that councils were equal to Scripture itself. Scripture always remained the highest authority. Councils were placed below Scripture but above other sources of authority. Even so, the canonists did not seriously consider the possibility that the early councils might have erred in defining the faith. A council supported by the agreement of the whole Church was regarded as a more reliable guide to doctrine than the judgment of any single pope.

It is also important to note that the canonists were mainly thinking of the great councils of the early Church, not of future councils that might be convened in their own time. Gratian listed eight ancient general councils, and among them the first four; Nicaea, Constantinople, Ephesus, and Chalcedon; were regarded as having special authority because they had defined the central doctrines of Christian belief. These councils, accepted by the whole Church, were seen as enduring landmarks of orthodoxy that even the pope could not overturn.

“Among universal councils there are eight outstanding ones and, of these, four have superlative authority … these the holy Roman church cannot change or mutilate by one iota.”

This statement reflects how medieval canonists understood the authority of the early ecumenical councils. The “eight outstanding” councils refer to the ancient councils recognized in the medieval Church, but special emphasis was placed on the first four. These councils were regarded as uniquely authoritative because they defined the central doctrines of Christianity; especially teachings about the Trinity and the nature of Christ.

The key point in the quotation is the claim that even the Roman Church cannot alter these councils “by one iota.” In other words, the pope does not possess the authority to revise or overturn the doctrinal definitions established by these councils. Their authority was seen as permanent because their teachings were believed to express the true meaning of Scripture and the consensus of the whole Church.

This reveals something important about medieval canonical thinking. The pope certainly had immense authority in governing the Church and settling disputes. But when it came to the foundational doctrines defined by the great ecumenical councils, the canonists believed those teachings stood above the authority of any individual pope. The pope could interpret or defend them, but he could not rewrite them.

This raises an interesting historical question. If the pope truly possessed an infallible teaching authority capable of defining doctrine independently, why would canonists insist that even the Roman Church could not alter the doctrinal decisions of these councils “by one iota”? Their statement suggests that doctrinal certainty was thought to reside not in the pronouncements of a single bishop; even the bishop of Rome; but in the shared judgment of the universal Church expressed through its councils.

Medieval canonists often said that the pope was bound by existing law when questions of faith were involved. What they meant by this becomes clear in the writings of Huguccio. Commenting on a case involving pope Anastasius, he explained that although a pope can change even good laws made by earlier popes when there is a good reason, there are certain things he cannot touch. A pope cannot alter the teachings of Scripture, the fundamental articles of faith, or doctrines necessary for salvation. In other words, the pope’s authority allowed him to revise many church laws, but it did not extend to changing the basic truths of the Christian faith.

This distinction also explains why some papal statements appeared to bind later popes. For instance, when pope Alexander III declared that Christ is both fully God and fully man, the statement carried lasting authority. However, this was not because Alexander’s own decree was considered unchangeable. Rather, it was binding because the statement simply repeated an ancient and universally accepted doctrine of the faith. In many similar cases found in the Decretum and the papal decretals, the authority of a papal statement came from the traditional doctrine it expressed, not from the personal authority of the pope who issued it.

The canonist Johannes Teutonicus also addressed the question of whether one pope could bind another. Discussing the controversy surrounding pope Anastasius and the Acacian schism, he argued that in certain circumstances a pope could indeed fall under a rule established by a previous pope. But this did not mean that one pope’s doctrinal opinion permanently set the standard for all later popes. Johannes’ point was different: if a pope fell into a known heresy that had already been condemned by a council or canon, he could incur the penalty laid down in those earlier laws. In that situation he would effectively cease to be pope because by becoming a heretic he would no longer stand within the Catholic Church.

Taken together, these discussions show that the Decretists did not believe that papal pronouncements were automatically permanent or beyond revision. When they said that a pope was bound by earlier decisions in matters of faith, they usually meant one of three things. First, the pope was bound by the doctrinal definitions of general councils that had already been approved by the Church. Second, he was bound by the teachings of Scripture and the accepted articles of faith that earlier decrees might repeat. Third, if a pope fell into heresy, he could be subject to penalties established by earlier canon law because by that very act he would have forfeited his authority.

What is striking is that none of this resembles the later idea that papal teachings are irreformable in themselves. The canonists believed that popes could make doctrinal mistakes and that such errors might later need correction by another pope. A strict theory of irreformable papal teaching would therefore have contradicted their basic assumptions.

Looking more broadly, the theology of the twelfth-century canonists differs sharply from the ecclesiology that emerged much later, especially at Vatican I. The canonists did not treat tradition as an independent source of revelation alongside Scripture, they did not speak of a special papal teaching office derived from the “keys,” and they often held that a general council carried greater authority than a pope acting alone in matters of faith. Most importantly, they did not teach that the pope possessed infallibility. On the contrary, many of their texts contrast the unfailing faith of the Church as a whole with the possible fallibility of individual popes. As far as the surviving evidence shows, neither canonists nor contemporary theologians in the twelfth century taught that the pope shared in the Church’s infallibility in the way later Catholic doctrine would claim.

In the thirteenth century the Franciscan theologian Bonaventure presented a stronger vision of papal authority than most earlier canonists. Later interpreters—including Joseph Ratzinger; have suggested that Bonaventure’s theology points toward the later doctrine of papal infallibility. In this view, the pope is not merely Peter’s successor or an administrative head of the Church, but now the living representative of Christ’s continuing rule. If that is the case, it becomes easier to imagine how the Church’s infallibility might be concentrated in the papal office.

Some Catholic scholars have even argued that Bonaventure anticipated the doctrine formally defined at Vatican I. Yet earlier canonists had generally described the pope’s authority in more limited terms. They spoke of the pope’s “plenitude of power,” but they understood this primarily as jurisdiction; the authority to govern and judge within the Church. Bishops, in their view, were successors of the apostles and therefore received their authority directly from Christ, not from the pope.

Bonaventure adopted a more centralized model. Following thinkers such as Thomas of York, he suggested that the authority of the entire hierarchy flows from the pope, who possesses the fullness of the authority Christ gave to the Church and distributes it to others. But this raises difficult questions. If all ecclesiastical authority flows from the pope, what becomes of the apostolic authority of the bishops themselves? Are they still successors of the apostles, or merely delegates of Rome? If Christ gave authority to the apostles collectively, on what basis can that authority later be said to pass through a single bishop?

Even deeper questions emerge. If the pope represents Christ’s ruling presence in the Church, does that mean his judgments carry divine certainty? Or does it simply describe a governing role within the Church’s structure? If infallibility truly belongs to the Church as a whole, why should it be concentrated in one office-holder? And if the pope possesses the fullness of authority, how are we to explain the historical reality that popes have contradicted one another, or even supported positions later judged erroneous?

The New Testament itself also raises questions for such a model. Where do we see a single universal ruler over the Church? Why do the apostles appear to act collectively rather than under the command of one supreme authority? If Peter had universal jurisdiction, why does the early Church in Acts deliberate through councils rather than simply receiving Peter’s ruling?

Ultimately the issue becomes unavoidable: is the later doctrine of papal infallibility the natural unfolding of apostolic teaching, or does it represent a later attempt to secure certainty by locating authority in one institutional office? And if doctrinal truth truly depends on the voice of one bishop, what happens when that bishop errs; or when history shows that several of them have?

A deeper problem with later theories of papal supremacy is that they often begin their analysis within the framework of Latin medieval Christianity, rather than the broader historical setting in which Christianity actually emerged. The early Church was born in the Middle East, not in Rome. The first centers of Christian life were Jerusalem, Antioch, and other eastern communities. Long before Rome developed claims of universal jurisdiction, Christianity had already spread throughout the eastern Mediterranean world.

In the New Testament itself there is no clear statement that Christ established the Roman see as the supreme authority of the Church. The authority given to the apostles appears collective. Christ speaks to Peter, but he also gives authority to the other apostles, and the early Church seems to function through shared leadership rather than through a single universal bishop. If this is the case, an important question arises: where exactly does the idea originate that the bishop of Rome inherited a unique governing authority over the entire Church?

The historical evidence complicates the later claim that such authority was present from the beginning. Early Christian centers such as Antioch, Alexandria, and Jerusalem exercised major influence in the life of the Church. The New Testament itself shows Peter active in Antioch and associated with the mission to the circumcised, while Paul and others carried the gospel across the eastern Mediterranean. The structure that later elevated Rome above all other churches developed gradually over centuries as Christianity moved into the Roman imperial world.

This raises several deeper questions about the development of papal authority.

If Christ truly intended to establish a single universal head of the Church located in Rome, why is this not clearly articulated in the New Testament?

Why does the earliest Christian leadership appear plural rather than monarchical?

And why did the most influential early Christian communities emerge in the eastern regions of the empire, rather than around the Roman episcopate?

Even more fundamentally, if the authority of the Church originally rested in the apostolic community as a whole, how did it later become concentrated in one episcopal office?

Was this concentration a natural unfolding of apostolic teaching, or was it shaped by the political and institutional environment of the crumbling Roman Empire once Christianity became aligned with imperial structures?

These questions do not necessarily deny that Rome eventually came to occupy a prominent place within the Church. But they challenge the assumption that Roman supremacy was present from the beginning. Instead, the historical evidence suggests a much more complex development, in which authority within Christianity gradually shifted as the Church’s geographic and political center moved westward.

At the heart of the entire debate lies a deeper tension that Brian Tierney himself recognized. On the one hand, the medieval theory of papal sovereignty required that the pope possess freedom of action. A sovereign ruler cannot be permanently bound by the decisions of earlier rulers; otherwise his authority would be constrained by the past. Papal monarchy, therefore, naturally emphasized the pope’s ability to legislate, interpret, and even modify earlier decisions when circumstances required it.

Yet the doctrine of papal infallibility points in the opposite direction. If a pope defines a teaching on faith or morals in an infallible way, that teaching becomes permanent and irreformable. Later popes cannot alter it without undermining the claim that the original definition was protected from error. In this sense, infallibility fixes certain teachings beyond change, while sovereignty demands the freedom to adapt, correct, or develop the Church’s laws and decisions over time.

The result is an unavoidable tension. A pope who must remain free to govern cannot be entirely bound by his predecessors; yet a pope whose predecessors have spoken infallibly cannot simply revise their judgments. To manage this difficulty, later theologians have increasingly narrowed the situations in which papal statements are considered infallible. The doctrine remains formally affirmed, but its practical application becomes extremely restricted.

The historical record examined by Brian Tierney reveals that the earliest canon lawyers of the medieval Church did not believe that the pope possessed an infallible teaching authority. They assumed that popes could err and that the ultimate security of the faith lay in the Church as a whole, expressed through Scripture, and the collective judgment of the Christian community. If these texts and traditions were present from the beginning, yet the doctrine itself only appeared much later, the question becomes difficult to avoid: does papal infallibility represent the preservation of an apostolic teaching, or the gradual construction of a theological solution to the problem of authority within an evolving institution? If the earliest canonists believed that the faith of the Church could not fail even though individual popes might err, and if the historical foundations of Roman supremacy remain debated, should the certainty of Christian truth ultimately rest in the voice of a single bishop; or in the enduring witness of the whole apostolic Church from which Christianity first emerged?

“But you are a chosen generation, a royal priesthood, a holy nation, a people for His own possession, that you may proclaim the excellencies of Him who called you out of darkness into His marvelous light.”— 1 Peter 2:9

Peter is describing all believers collectively, not a special clerical class. The phrase “royal priesthood” echoes Exodus 19:6, where Israel is called a kingdom of priests.

“You also, like living stones, are being built into a spiritual house to be a holy priesthood, offering spiritual sacrifices acceptable to God through Jesus Christ.”— 1 Peter 2:5

Together these verses emphasize the idea that the priestly role belongs to the whole community of believers, a point many theologians later described as the “priesthood of all believers.”

Blessed Sabbath from sunset today.

Peace.