Below is not a formal blog article, but a copy-paste of a response I made to an Anglican interlocutor who had denied that St. Thomas Aquinas held to something akin to what would later be defined as the infallibility of the Pope when the latter speaks ex cathedra, i.e. as supreme pastor of all Christians, in a manner to bind the universal church on a teaching of faith and morals.
The first reference I would draw the readers to is Quodlibet IX, article 16 where St. Thomas poses the question of when the Popes canonize Saints, can we be certain they are truly in heaven, or whether there is still reason to doubt.
“Dico, ergo, quod judicium eorum qui praesunt Ecclesiae, potest errare in quibuslibet, si personae eorum tantum respiciantur. Si vero consideretur divina providentia, quae Ecclesiam suam Spiritu sancto dirigit, ut non erret, sicut ipso promisit. Joan 14, quod Spiritus adveniens doceret omnem veritatem, de necessariis scilicet ad salutem; certum est quod judicium Ecclesiae universalis errare in his quae ad fidem pertinet, impossible est”
“I say, therefore, that the judgement of those who preside over the Church can make errors in any matter insofar as their private persons are concerned. If, however, we consider the divine providence of God, the Holy Spirit…..it is certain that it is impossible for the judgement of the universal Church to be in error”
Now, lest you concede this on behalf of some vague and undefined notion of “universal church”, we should first be aware that for Aquinas, the universal Church spoke through the Pope. He even used the infallible utterance of Caiphas the High Priest to compare the sort of divine protection against error in the teaching of the Pope on this very matter.
“..cum cayphas, quamvis nequam, tamen quia pontifex legatur etiam inscius prophetasse” Quod Ix, article 16.
In his Catena Aurea (Golden Chain) of the four gospels (Lectio #3), where he seeks to pile a Patristic commentary on the texts of Matthew 16 and Luke 22:32. Aquinas quotes from Pseudo-Cyrill with the following words:
“According to this promise of the Lord, the Apostolic Church of Peter remains pure and spotless from all leading into error, or heretical fraud, above all Heads and Bishops, and Primates of Churches and people, with its own Pontiffs, with most abundant faith, and the authority of Peter. And while other Churches have to blush for the error of some of their members, this reigns alone immoveably established, enforcing silence, and stopping the mouths of all heretics” [granted, this was probably not written by holy Cyril, but why would Aquinas use it in his Catena Aurea if he himself did not consider it true? And besides, with as man spurious texts Aquinas cites from the Fathers to prove a certain point, there is always a corresponding text which no one doubts which proves the same. See here for a short article by Dr. James Likoudis on this matter].
In his Contra Errores Graecorum , chapter 36, why would Aquinas write the following?
“It is also demonstrated that to the aforesaid Pontiff belongs the right of deciding what pertains to faith. For Cyril in his Thesaurus says: “Let us remain as members in our head on the apostolic throne of the Roman Pontiffs, from whom it is our duty to seek what we must believe and what we must hold.”
And for further grounds upon which Aquinas asserts the above, he says in the Summa (II, q. 1, art. 10) regarding the addition of the filioque to the holy creed:
“….a new edition of the symbol becomes necessary in order to set aside the errors that may arise. Consequently to publish a new edition of the symbol belongs to that authority which is empowered to decide matters of faith finally, so that they may be held by all with unshaken faith. Now this belongs to the authority of the Sovereign Pontiff, “to whom the more important and more difficult questions that arise in the Church are referred,” as stated in the Decretals” [again, these are forged Decretals, but there are authentic texts that no historian disputes which speak to the same – see the Likoudis link above].
Now, the telos of “unshaken faith” is the achievement of certainty. Why would this be established by the authority of the Pope if there was no divine protection against error for Papal teaching (i.e. the transmitter of data)?
In answer to the objection of how the Council of Chalcedon locked the creed, Aquinas writes (same Article as above, reply to objection 2):
“This prohibition and sentence of the council was intended for private individuals, who have no business to decide matters of faith: for this decision of the general council did not take away from a subsequent council the power of drawing up a new edition of the symbol, containing not indeed a new faith, but the same faith with greater explicitness. For every council has taken into account that a subsequent council would expound matters more fully than the preceding council, if this became necessary through some heresy arising. Consequently this belongs to the Sovereign Pontiff, by whose authority the council is convoked, and its decision confirmed.”
In his Lectura on the Gospel of St. Matthew , a classroom lecture from his 2nd stay in Paris, Aquinas writes the following from the texts on St. Peter:
“Ecclesia tamen Romana non fuit ab haereticis depravata quia supra petram erat fundata. Unde in Constantinopli fuerunt haeretici et labor apostolorum amissus erat; sola Petri ecclesia inviolata permansit (Luke 23:32). Et hoc non solum refertur ad Ecclesiam Petri, sed ad fidem Petri, et ad totam occidentalem Ecclesiam. Unde credo quod occidentales maiorem reverentiam debent Petro quam aliis Apostolis”
“He argued that although the heresies existed in other church — Constantinople was the typical example – through the centuries the Church of Rome alone had kept its faith whole. In it, Christ’s prayer (i.e. to Peter of unfailing faith) is fulfilled, and from it the true faith had spread to the entire Western Church. Yet here there is an important additional claim: that the faith remained whole was due not only to the Roman church, but also to the faith of St. Peter” (The Dominicans and the Pope: Papal Teaching Authority in the Medieval and Early Modern Thomist Tradition, Ulrich Horst, O.P. , page 18)
Thus, I think it is clear that Aquinas held that the transmitter of the content of divine revelation , and not just the transmitted, is divinely preserved from error, in light of the fact that he discriminated Peter and his successors (the Roman church) in the midst of all the others as having the divinely bestowed authority, not just for the sake of some external ecclesial polity, but also on matters of religious faith/dogma (i.e. the Creed, the dogma of the procession of the Holy Spirit from both the Father and the Son).
We may summarize thusly:
(1) It is impossible for the Church to err on faith/morals
(2) The Pope speaks on behalf of the Church (though, not in his private personal capacity, so on that you are right), in order to providentially secure an “unshaken faith” in the members of the Church
(3) The Roman pontiff has always kept the faith in his official teaching capacity, in fulfillment of the divine promise that this will be so until the parousia of Christ. While other churches, bishops, pontiffs, and religious teachers have erred in faith, the prelate of the Roman see has not, in light of what is promised to St. Peter and to his successors.