Benedict XVI is one of the few pontiffs with the brainpower to make a case for his own job. Let’s see how he does:
That the primacy of Peter is recognizable in all the major strands of the New Testament is incontestable.
“Primacy” is a loaded word. Peter was a natural, albeit wavering, leader. These are personal qualities, not official qualities. His character traits are hardly transferable to an ecclesiastical office. To do so would be to personify an office, which is a category mistake.
And although Peter was a leader of the early church, he was not the only leader. He was not even the leader of the mother church in Jerusalem.
The real difficulty arises when we come to the second question: Can the idea of a Petrine succession be justified? Even more difficult is the third question that is bound up with it: Can the Petrine succession of Rome be credibly substantiated?
Concerning the first question, we must first of all note that there is no explicit statement regarding the Petrine succession in the New Testament. This is not surprising, since neither the Gospels nor the chief Pauline epistles address the problem of a postapostolic Church—which, by the way, must be mentioned as a sign of the Gospels' fidelity to tradition.
They don’t address the problem of a postapostolic church? The very fact that you have a NT, that the Apostles bequeathed to the church a permanent written record of the Christ-Event and its theological significance in the Gospels and Pauline epistles and other NT documents is nothing if not a preparation for the postapostolic church.
In addition, the NT does set up a rudimentary form of church office to carry on the work of the Apostles. And it’s rudimentary because that’s all that’s needed in the life of the church. No elaborate bureaucracy is required.
Ratzinger is begging the question in his own favor by assuming that the NT left the problem unresolved. Why presume that NT teaching is incomplete in this respect? Why presume that the Apostolate left the job half-finished? Why not credit the NT authors with having said what needed to be said?
Indirectly, however, this problem can be detected in the Gospels once we admit the principle of form critical method according to which only what was considered in the respective spheres of tradition as somehow meaningful for the present was preserved in writing as such.
i) What about what was meaningful for the future as well as the present?
ii) This form-critical axiom will also be relevant to the question of dating. If, as the form critics would have it, the gospels were written late, as etiologies, to historicize preexisting dogma; if, that is to say, the gospel writers make up stories to illustrate the doctrine and practice of the post-70 AD church, so that the post-70 AD church supplies the sitz-em-leben of the Gospels, then why, on his own accounting, do the Gospels fail to address the problem of the postapostolic church if they were written in the postapostolic era? His position is self-refuting.
In those writings of the New Testament that stand on the cusp of the second generation or else already belong to it-especially in the Acts of the Apostles and in the Pastoral Letters—the principle of succession does in fact take on concrete shape.
Notice that Ratzinger is implicitly treating the Pastorals as deutero-Pauline. This is a euphemism for forgery.
The Protestant notion that the "succession" consists solely in the word as such, but not in any "structures", is proved to be anachronistic in light of what in actual fact is the form of tradition in the New Testament. The word is tied to the witness, who guarantees it an unambiguous sense, which it does not possess as a mere word floating in isolation. But the witness is not an individual who stands independently on his own. He is no more a wit ness by virtue of himself and of his own powers of memory than Peter can be the rock by his own strength. He is not a witness as "flesh and blood" but as one who is linked to the Pneuma, the Paraclete who authenticates the truth and opens up the memory and, in his turn, binds the witness to Christ. For the Paraclete does not speak of himself, but he takes from "what is his" (that is, from what is Christ's: (Jn 16: 13).
i) This is a straw man argument. Except for say, the Plymouth Brethren, most Protestants do not deny that you have church office in the NT. There is a “structure” in place.
The real issue is whether the high churchman is entitled to go beyond the NT church to mandate all manner of unscriptural accretions.
ii) How is the appeal to the Holy Spirit relevant to his case? Evangelicals do not deny that the Apostles and other NT writers were inspired. So how does the “pneumatic” criterion distinguish the Catholic position from the Protestant position?
This binding of the witness to the Pneuma and to his mode of being-"not of himself, but what he hears" -is called "sacrament" in the language of the Church. Sacrament designates a threefold knot-word, witness, Holy Spirit and Christ-which describes the essential structure of succession in the New Testament. We can infer with certainty from the testimony of the Pastoral Letters and of the Acts of the Apostles that the apostolic generation already gave to this interconnection of person and word in the believed presence of the Spirit and of Christ the form of the laying on of hands.
i) Notice the leap of logic. How does the category of “sacrament” emerge from what he just said? It doesn’t. He’s laid no foundation for this momentous inference. It just pops in out of the blue. This is, indeed, a key step in his argument, but he didn’t arrive at that juncture by stepwise logic. Rather, he’s skipping over many preliminary steps to get there. Observe the anachronistic equation of holy orders with the imposition of hands. There’s no logical transition from point A to point Z.
In opposition to the New Testament pattern of succession described above, which withdraws the word from human manipulation precisely by binding witnesses into its service, there arose very early on an intellectual and anti-institutional model known historically by the name of Gnosis, which made the free interpretation and speculative development of the word its principle. Before long the appeal to individual witnesses no longer sufficed to counter the intellectual claim advanced by this tendency. It became necessary to have fixed points by which to orient the testimony itself, and these were found in the so-called apostolic sees, that is, in those where the apostles had been active. The apostolic sees became the reference point of true communio.
i) The Gnostics didn’t merely reinterpret the Bible. They wrote their own apocryphal “scriptures.”
ii) Why is it necessary to counter an intellectual claim by an anti-intellectual appeal to tradition? Why not counter an intellectual claim on its own grounds? Why not point out that the Gnostics were guilty of Scripture-twisting?
iii) Tradition is also subject to interpretation.
iv) Restricting the interpretation of the Bible to the sole jurisdiction of the “Church” does not withdraw the Bible from human manipulation, but merely relocates the arena of manipulation. If the Gnostics can manipulate the Scriptures, so can the bishops.
But among these sees there was in turn–quite clearly in Irenaeus of Lyons–a decisive criterion that recapitulated all others: the Church of Rome, where Peter and Paul suffered martyrdom. It was with this Church that every community had to agree; Rome was the standard of the authentic apostolic tradition as a whole.
Moreover, Eusebius of Caesarea organized the first version of his ecclesiastical history in accord with the same principle. It was to be a written record of the continuity of apostolic succession, which was concentrated in the three Petrine sees Rome, Antioch and Alexandria-among which Rome, as the site of Peter's martyrdom, was in turn preeminent and truly normative. 
This may well be an accurate description of what took place, but what Ratzinger is describing is a polemical short-cut. Instead of out-arguing the heretics, appeal is made to tradition on the assumption that the teaching of a then-current apostolic see is identical with the teaching of the apostles. But this assumption is quite tendentious. For example, the seven churches of Asia Minor (Rev 2-3) were apostolic sees, founded by the Apostle John. Yet some of them were already on the brink of apostasy.
This leads us to a very fundamental observation.  The Roman primacy, or, rather, the acknowledgement of Rome as the criterion of the right apostolic faith, is older than the canon of the New Testament, than "Scripture".
We must be on our guard here against an almost inevitable illusion. "Scripture" is more recent than "the scriptures" of which it is composed. It was still a long time before the existence of the individual writings resulted in the "New Testament" as Scripture, as the Bible. The assembling of the writings into a single Scripture is more properly speaking the work of tradition, a work that began in the second century but came to a kind of conclusion only in the fourth or fifth century. Harnack, a witness who cannot be suspected of pro-Roman bias, has remarked in this regard that it was only at the end of the second century, in Rome, that a canon of the "books of the New Testament" won recognition by the criterion of apostolicity-catholicity, a criterion to which the other Churches also gradually subscribed "for the sake of its intrinsic value and on the strength of the authority of the Roman Church".
We can therefore say that Scripture became Scripture through the tradition, which precisely in this process included the potentior principalitas–the preeminent original authority–of the Roman see as a constitutive element.
Two points emerge clearly from what has just been First, the principle of tradition in its sacramental form-apostolic succession—played a constitutive role in the existence and continuance of the Church. Without this principle, it is impossible to conceive of a New Testament at all, so that we are caught in a contradiction when we affirm the one while wanting to deny the other.
This is hardly a new argument. It’s a stock objection to the Protestant rule of faith. By way of reply:
i) The incomplete state of the canon is irrelevant to the authority of Scripture in relation to the institutional church.
To take a comparison, the OT canon was far from complete when the preexilic prophets were called up to denounce a decadent religious establishment. The Levitical priesthood preexisted the exilic and postexilic books of the Bible. That did not prevent the prophets from denouncing a corrupt religious establishment.
Just imagine an apostate high priest using Ratzinger’s argument on Isaiah or Jeremiah: “Now look here, Jeremiah: the priesthood is older that the canon of the OT. The canonization of the OT is more properly speaking the traditional work of Ezra. So don’t you go quoting the Mosaic Covenant to me! Without the primacy of the priesthood, it is impossible to conceive of an OT at all, so that you are caught in a contradiction when you affirm the one while wanting to deny the other!”
ii) Since the books of the NT were written at different times and places, it naturally took a while to collate them all. But that is a mere formality. Unless the NT documents are of canonical quality, they cannot be included in the canon--and if they are of canonical quality, they cannot be excluded from the canon.
iii) Just as the NT writings originally existed in geographical isolation, the NT church consisted of house-churches scattered hither and yon. So the state of the NT church is analogous to the state of the NT corpus. Just as the NT canon was instantiated in different times and places, the NT church was instantiated in different times and places. Some NT books were written before some NT churches were founded. Just as the NT writings weren’t written or collated all at once, the apostolic churches (or “sees”) weren’t planted all at once.
And if you want to extend the process of canonization into the 5C, you can just as well extend the process of Roman primacy into the 5C and beyond. So the argument from chronological priority is a double-edged sword.
iv) We aren’t bound by the criterion of Eusebius or Irenaeus. Ratzinger is confounding a historical process with a process of verification. We can have different criteria to justify the same historical outcome.
v) Assuming, for the sake of argument, that the NT does bear witness to the "primacy" of Peter, why is Ratzinger appealing to the NT to validate the papacy? If he's going to argue that Roman primacy is the criterion for the NT canon, then how can he turn around and invoke the NT to legitimate the papacy? See the circular reasoning?
We can add that Rome and Antioch were conscious of succeeding to the mission of Peter and that early on Alexandria was admitted into the circle of Petrine sees as the city where Peter's disciple Mark had been active.
Were “conscious” of succeeding Peter. Wow, how’s that for proof postive! Have you ever noticed that every heretic and cult-leader is privy to this sense of consciousness as well?
Having said all that, the site of Peter's martyrdom nonetheless appears clearly as the chief bearer of his supreme authority and plays a preeminent role in the formation of tradition which is constitutive of the Church-and thus in the genesis of the New Testament as Bible; Rome is one of the indispensable internal and external- conditions of its possibility. It would be exciting to trace the influence on this process of the idea that the mission of Jerusalem had passed over to Rome, which explains why at first Jerusalem was not only not a "patriarchal see" but not even a metropolis: Jerusalem was now located in Rome, and since Peter's departure from that city, its primacy had been transferred to the capital of the pagan world. 
This geographical criterion is a non-sequitur. The logical form of the argument would be that whomever Peter ordained (through the imposition of hands) was Peter’s successor. Of course, in his far-flung ministry, Peter would have had occasion to lay hands on any number of individuals in different parts of the Roman Empire, such as the see of Antioch. And they, in turn, would ordain successors, such as the see of Alexandria.
So Ratzinger’s argument either proves too much or too little. And Ratzinger is about as capable as they come.