In Adolf Von Harnack vs. the Monarchial Episcopacy in Rome, I refuted a recent Catholic convert's attempt to abuse Adolf Von Harnack's The Constitution and Law of the Church in the First Two Centuries (trans. F.L. Pogson; London: Williams and Norgate, 1910) to support Roman Catholic claims about the papacy. For an addendum of sorts, consider the following from Eamon Duffy, Saints and Sinners: A History of the Popes (2d ed; New Haven: Yale University Press, 2001)
All the essential claims of the modern papacy, it might seem, are contained in this Gospel saying about the Rock, and in Irenaeus' account of the apostolic pedigree of the early bishops of Rome. Yet matters are not so simple. The popes race their commission from Christ through Peter, yet for Irenaeus the authority of the Church at Rome came from its foundation by two Apostles, not by one, Peter and Paul, not Peter alone. (p. 2)
The Bishops of Rome
It was against the mid-century background of ritual and doctrinal confusion that the 'monarchic episcopate', the rule of the church by a single bishop, was accepted in Rome. Throughout the Mediterranean world the rule of the bishops came to be seen as a crucial defence against heresy. As Irenaeus wrote in his Treatise against the Heresies, 'It is within the power of anyone who cares, to find the truth and know the tradition of the Apostles . . . we are able to name those who were appointed bishops by the Apostles in the churches and their successors down to our own times.' There is no sure way to settle on a date by which the office of ruling bishop had emerged in Rome, and so to name the first Pope, but the process was certainly complete by the time of Anicetus in the mid-150s, when Polycarp, the aged Bishop of Smyrna, visited Rome, and he and Anicetus debated amicably the question of the date of Easter. Polycarp, then in his eighties, had known John, the 'beloved disciple', in his old age. He therefore strongly urged direct apostolic authority for the practice of the churches from Asia Minor (and their satellite ethnic congregations in Rome itself) of keeping Easter at Passover. Anicetus contented himself more modestly with defending the practice of 'the presbyters who had preceded him; in having no separate Easter festival. (p. 13)