Again, where do you get the "previous teaching" part of the definition of ex cathedra?
If there is some powerful interest supporting the error, it may temporarily gain currency. However, any Catholic who detects heresy from ANY source is obligated to resist it.
Did a powerful interest called Pope Honorius promulgate and teach heresy in his official letters, as bishop of Rome, to Sergius, in words "hurtful to the soul", and did that "former Pope of Old Rome, who with the help of the old serpent" scatter "deadly error", or not?
Do you understand how this logic is linear and not at all circular?
It is circular because you simply assume what must proved; namely, that Popes are infallible in their teaching ex cathedra, and therefore it is impossible for any Pope to have erred in a teaching on faith or morals. Regardless of what the historical facts are, all you have to do is claim that any given teaching was not intended it to be a binding statement upon the entire church. If we ask for proof of the dogma we get the dogma as proof, just as you have done with me. It is entirely circular, which is why you completely ignore any historical facts concerning Honorius' anathematization as a heretic.
Cordially,
From your response it would seem that what I have said so far does not make any sense to you. I think I now understand why. I neglected to explain how the Church defines doctrine.
Just about all Catholic doctrine is implicit in her sacraments, such as the mass, baptism, confession, marriage, and consecration of priests, or in the Church hierarchical structure. The sacraments and hierarchy was set by the Apostles. Other than by Scripture, the Church does not define doctrine explicitly unless it is necessary to counter an heresy. Explicitly defined teachings are always based upon implicit teachings that have existed for many years or since the beginning of the Church. Petrine infallibility has been operational since it was established by Christ and exercised by Peter's early successors.
Did a powerful interest called Pope Honorius promulgate and teach heresy in his official letters, as bishop of Rome, to Sergius, in words "hurtful to the soul", and did that "former Pope of Old Rome, who with the help of the old serpent" scatter "deadly error", or not?
Yes, apparently, but I have been trying to show you that this issue of Honorius is moot to our discussion because it does not undermine the doctrine of infallibility.
It is circular because you simply assume what must proved; namely, that Popes are infallible in their teaching ex cathedra, and therefore it is impossible for any Pope to have erred in a teaching on faith or morals.
I was not specifically addressing the proof of infallibility found in Scripture. That is an issue separate from question of whether Honorius undermined infallibility. Papal infallibility is and has always been, at least implicitly, a core doctrine of the Catholic Church. The great bulk of infallible doctrine was fully defined by Scripture and the papally certified councils that took place prior to the Church's finalization of her NT canon.
No Catholic of any rank is allowed to transgress infallible doctrine. If a Catholic pope or Catholic peasant does so, his actions are illicit. The Vatican I Council definition of ex cathedra did not say this because it is a basic tenet know to all. Since a pope is not allowed to transgress infallible doctrine, he obviously cannot do so ex cathedra.