Ancient and medieval views of papal authority
Of the Petrine texts, Matthew 16:18 ff. is clearly central and has the distinction of being the first scriptural text invoked to support the primatial claims of the Roman bishops. Although the exact meaning of this passage was debated by patristic exegetes (early Church Fathers who in their interpretation of the Bible used critical techniques), the tradition of Roman preeminence developed very early in the history of the church. In the late 4th and 5th centuries there was an increasing tendency on the part of Roman bishops to justify scripturally and to formulate in theoretical terms the ill-defined preeminence in the universal church that had long been attached to the Roman church and to its bishop. Thus, Damasus I, despite the existence of other churches of apostolic foundation, began to call the Roman church “the apostolic see.” At about the same time, the categories of Roman law were borrowed to explicate and formulate the prerogatives of the Roman bishop. The process of theoretical elaboration reached a culmination in the views of Leo I and Gelasius I (reigned 492–496), the former understanding himself not simply as Peter’s successor but also as his representative, or vicar. He was Peter’s “unworthy heir,” possessing by analogy with the Roman law of inheritance the full powers Peter himself had wielded—these powers being monarchical, since Peter had been endowed with the principatus over the church.
On a purely theoretical level, the distance between the claims advanced by Leo I and the position embodied in the primacy decree of Vatican I is not great. Medieval popes, such as Gregory VII, Innocent III, and Innocent IV, clarified in both theory and practice the precise meaning of that fullness of power (plenitudo potestatis) over the church to which, according to some scholars, Leo I himself had laid claim. In this they were aided not only by the efforts of publicists such as the 13th-century Italian theologian and philosopher Giles of Rome, also known as Aegidius Romanus, who magnified the pope’s monarchical powers in unrestrained and secular terms, but also by the massive development during the late 11th, 12th, and 13th centuries of canon law, which made increasing use of Roman law and legal practices. Gratian’s Decretum (c. 1140), the unofficial collection of canons that became the fundamental textbook for medieval students of canon law, laid great emphasis on the primacy of the Roman see, accepting as genuine certain canons that were based on long-standing tradition but were actually the work of 8th- and 9th-century forgers. Two such canons were restated by the 1917 Code of Canon Law as the principles “that there cannot be an ecumenical council which is not convoked by the Roman Pontiff” and that “the First See is under the judgment of nobody.”
The prevalence of such ideas and the absence of a formidable challenge to papal primatial claims during the High Middle Ages explain the lack of any conciliar definition of the Roman primacy at the great “papal” general councils of that period. Hence it took the (abortive) attempt at reunion with the Orthodox Church at the Council of Ferrara-Florence in 1439 to evoke the first solemn conciliar definition of the Roman primacy, which was included in the decree of union with the Greeks (Laetentur coeli) as follows:
We define that the Holy Apostolic See and the Roman Pontiff hold the primacy over the whole world, that the Roman Pontiff himself is the successor of Peter, prince of the Apostles, that he is the true vicar of Christ, head of the whole church, father and teacher of all Christians, and [we define] that to him in [the person of] Peter was given by our Lord Jesus Christ the full power of nourishing, ruling and governing the universal church; as it is also contained in the acts of the ecumenical councils and in the holy canons.