Historically, I don’t think you can find referencec for Papal Infallibility before the 14th century though.
That said…
As I understand it, the dogma such as Papal Infallibility came with some rather strong consequences for non-assent. For me, the main problem is that it the church is creating new stumbling blocks to salvation.
I think you will find the idea present well before that even if it is not framed in terms of “infallibility.” To make our task easier, let’s consider instead the basically equivalent idea that the pope is the final judge in matters of faith and that all the faithful are bound by his decisions. How could the pope have this authority apart from some guarantee of infallibility. We see this idea clearly present throughout the history of the Church. For instance, in his
Contra Errores Graecorum (written 1263), Thomas Aquinas writes,
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.” Footnote And Maximus in the letter addressed to the Orientals says: “All the ends of the earth which have sincerely received the Lord and Catholics everywhere professing the true faith look to the Church of the Romans as to the sun, and receive from it the light of the Catholic and Apostolic Faith.” Footnote Rightly so, for Peter is recorded as the first to have, while the Lord was enlightening him, confessed the faith perfectly when he said to him (Matt. 16:16): You are the Christ, the Son of the living God. And hence the Lord also said to him (Lk. 22:32): I have prayed for you, Peter, that your faith may not fail.”
dhspriory.org/thomas/ContraErrGraecorum.htm#b36
We can see this same principle earlier on. For example, Peter Chrysologus writes to Eutyches (Fifth Century),
In all matters, we urge you, honorable brother, attend obediently to the things which are written by the most blessed pope of Rome: for blessed Peter, who in his own seat both lives and presides, provides to those seeking the truth of the faith. Indeed, for the pursuit of peace and faith, we cannot decide cases of faith apart from the agreement of the bishop of Rome.
(Letters of St. Leo the Great, 25.2)
www.documentacatholicaomnia.eu/01p/0440-0461,_SS_Leo_I._Magnus,_Epistolae,_MLT.pdf
The fact that people did not always “attend obediently” to the rulings of the pope does not mean that it was not believed.
Even earlier Irenaeus writes (Second Century) that all Churches must agree with the Church of Rome on account of its preeminent authority.
Since, however, it would be very tedious, in such a volume as this, to reckon up the successions of all the Churches, we do put to confusion all those who, in whatever manner, whether by an evil self-pleasing, by vainglory, or by blindness and perverse opinion, assemble in unauthorized meetings; [we do this, I say,] by indicating that tradition derived from the apostles, of the very great, the very ancient, and universally known Church founded and organized at Rome by the two most glorious apostles, Peter and Paul; as also [by pointing out] the faith preached to men, which comes down to our time by means of the successions of the bishops. For it is a matter of necessity that every Church should agree with this Church, on account of its preeminent authority, that is, the faithful everywhere, inasmuch as the tradition has been preserved continuously by those [faithful men] who exist everywhere.
(Against Heresies 3.3.2)
newadvent.org/fathers/0103303.htm
As for “strong consequences for non-assent,” isn’t that the idea? What purpose is it for the pope to have the prerogative to define matters of faith if we don’t want to assent to it?
For my Catholic friends, I’m curious - is there any new dogma declared infallible by the Bishop of Rome in the early church history? And if so, was there understanding at the time that it was because the Bishop of Rome made these pronouncement that there were considered infallible.
I think the mistake is to assume that the pope defines doctrine independent of the rest of the Church. The better question that we should ask first would simply be whether the pope decided matters of dogma, and the answer is that he did. Then we can ask the question whether it was understood that the pope’s decisions in matters of faith were binding on account of his office. I think it is clear from the quotations I provided above and others that it was understood that the bishop of Rome possessed that authority as the highest judge in matters of faith. Now, we could also look at those who dissented from the pope and say that this shows that the pope was not infallible (Cyprian would make a good example). The problem with the historical record is that we only have what little was preserved and we we only have a limited idea of the context. Nevertheless, at the very least, it appears that many did have the basic idea of papal infallibility.