Did Blessed John Henry Newman say
"It was Oxford that made me a Catholic"? Or did he say
"It was the Fathers that made me a Catholic"? Or did he, as I rather think, say both?
It is certainly true that Henry Manning said, referencing Newman, that "it is the old Anglican, patristic, literary Oxford tone transplanted into the Church". And who durst say that an Archbishop of Westminster can err?
For Newman, what has actually happened in the history of the Church makes a good starting point.
This is one of the reasons why I have been so attracted by Newman's argument that the papal or episcopal teaching office may be seen as being in 'Suspense' if the pope or bishop stops using it, or gets into the habit of using it improperly. We do not, in my view, profit by discussing 'formaliter' and 'materialiter'. If we adopt Newman's modes of discourse, discussions of how or whether a Roman bishop can lose his office, or the exercise of it, become no less fascinating but quite a lot less necessary. We do not need to break or fracture the canonical unity of the Church Militant, the Church Visible.
Blessed John Henry came to his conclusions as the result of his long studies of the Arian Crisis, in which, for sixty years, a pope and most bishops taught error or at least subverted the Truth by their weakness. The Magisterium was indeed in suspense. It is an objective fact of History. Syllogisms be damned: Newman's accounts and interpretations describe reality. That is what makes them, and his methods, attractive.
I have written before about Pope Honorius. We might also consider the Great Schism of the West. If you believe that the 'Urbanist' popes were the true popes, then from 1378 until 1415, the papal Magisterium was in suspense in France, Scotland, Spain, and Naples. If, on the other hand, you are a 'Clementine', then, from 1378 until 1429, the papal teaching office was in suspense in the Empire, England, Ireland, North Italy, Poland, Hungary, and Northern Europe (editions of the Annuario pontificio have given fluctuating lists of 'true' popes, but there has never been a Magisterial decision ... the pompous list of popes on the walls of Westminster Cathedral gets its shambolic knickers into quite a self-contradictory twist).
The history of the Church is not a tidy phenomenon in which we can say: there has never been a dodgy pope because, as soon as a pope does become dodgy, he ... like magic!! ... 'Beam me up, Scotty!' ... automatically ceases to be pope (even if nobody is actually aware that this invisible cessation has occurred).
Church history is a messy business in which there really have been dodgy popes, and ... whatever all the syllogisms in all the universe might anxiously jostle to say about it ... they have not thereby ceased to be popes or ceased to be recognised as such.
So when Sedevacantists solemnly and under threat of Sin tell Christian people that they ought never go to Mass unless they can cadge a lift to their nearest sedevacantist Mass a thousand or three miles away, they ought to remember that for half a century during the Great Western Schism, half the Christians in Europe attended Masses in which an 'invalid' pope was mentioned in the una cum. They also ought to remember that, in cases where there is a genuine doubt, a stricter view should not be imposed on penitents even if that stricter view appears, to the mind of the Confessor himself, to be the very much more probable view (vide H Davies Vol I pp 91sqq). It is a grave responsibility to drive Christifideles laicos away from the Sacraments (I am not discussing here the question of Sacramental Validity).
During the Western Schism, were those who moved across the border between England and Scotland required to be absolved from Schism because they had been attending Masses in which the 'wrong' pope was named? When the Schism was over, did the Council of Constance require the clergy and laity of half Europe to go to confession to be absolved of the 'sin' of attending Masses in which a 'wrong' papal claimant was silently named? Go on, give me a Denzinger number!