At the Council of Florence, the Council Fathers, both Greek and Latin, discussed in a Very Irenic and - there is no other word for it - almost Ecumenical Spirit, for the most part. They admitted the Authority of all the Fathers and Doctors, both Eastern and Western, and tried to arrive at a theological consensus. They almost did, but then the hoped-for Holy Union between Eastern and Western Christendom sadly did not last: "
"Eugenius, bishop, servant of the servants of God, for an everlasting record. With the agreement of our most dear son John Palaeologus, illustrious emperor of the
Romaioi, of the deputies of our venerable brothers the patriarchs and of other representatives of the eastern church, to the following.
Let the heavens be glad and let the earth rejoice. For,
the wall that divided the western and the eastern church has been removed, peace and harmony have returned, since the corner-stone, Christ, who made both one, has joined both sides with a very strong bond of love and peace, uniting and holding them together in a covenant of everlasting unity. After a long haze of grief and a dark and unlovely gloom of long-enduring strife,
the radiance of hoped-for union has illuminated all." (From: Laetentur Caeli)
https://en.wikipedia.org/wiki/Bull_of_Union_with_the_Greeks
We all know the difficulties that ensued. But I firmly believe it is our generation's task to complete the holy work that they so happily began.
So, where were we? Oh yeah, Canon 28 of Chalcedon was being discussed, as was EC 6, Constantinople III, and Pope St. Agatho's Letter.
Biblical Catholic has a good summary, and the words of Patriarch Anatolius of Constantinople are illuminating as to what authority the 5th Century Orthodox Church of Constantinople recognized in the Apostolic See of Rome: " Even so,
the whole force of confirmation of the acts was reserved for the authority of Your Blessedness. Therefore, let Your Holiness know for certain that I did nothing to further the matter, knowing always that I held myself bound to avoid the lusts of pride and covetousness.
-- Patriarch Anatolius of Constantinople to Pope Leo, Ep 132 (on the subject of canon 28 of Chalcedon).
So, the matter was settled; and, for the next 6 centuries, all Eastern churches speak of only 27 canons of Chalcedon -- the 28th Canon being rendered null and void by Rome's "line item veto."
This is supported by all the Greek historians, such as Theodore the Lector (writing in 551 AD), John Skolastikas (writing in 550 AD), Dionysius Exegius (also around 550 AD); and by Roman Popes like Pope St. Gelasius (c. 495) and Pope Symmachus (c. 500) -- all of whom speak of only 27 Canons of Chalcedon."
http://www.biblicalcatholic.com/apologetics/a35.htm
So can we not see the Pope was asked to confirm the Council, and was also recognized as having the power to make a "line item veto"?
But nevertheless, even if Orthodox say, "The Pope's approval was necessary but not sufficient", that's ok. Then let the same be applied today.
Regarding Pope St. Agatho, a scholar who tries to "refute" the letter was cited. But did the Council Fathers try to "refute" it? No, they did not.
Rather, they unanimously said, "Peter has spoken through Agatho", just like EC4 had said "Peter has spoken through Leo". This is the mind of the Church.
Someone mentioned unanimous or universal acceptance. Does this universal acceptance of Pope St. Agatho's Letter at EC 6 not make it correct?
"
We have had with us the most high Prince of the Apostles, for we have received encouragement and a written declaration of the sacred mystery from his imitator and the successor of his See; ... and
Peter has spoken through Agatho.2
4 http://www.cchahistory.ca/journal/CCHA1965/Hanrahan.htm
Some of the second-millenium, post-schism developments, particularly after Florence, are specific to the West only. But above is First Millenium.
What Byzantine and other Eastern Great Saints of the First Millenium said about the Papacy can reasonably be applied to the Papacy today.
If Orthodox believe "Approval from all 5 Patriarchs is necessary to make a Council Ecumenical", then why not ask all 5 Patriarchs to approve?
As a Catholic, I believe seeking the approval from all in the Pentarchy is a legitimate discipline to follow. Question is, why not follow at least that?
I believe most Second Millenium Orthodox Councils could easily be accepted by Catholics. For e.g. the Council of Dositheus is clearly Catholic.
In a similar way, it would be nice if Orthodox accepted, for e.g. the decrees of Trent on the Sacraments. It teaches Real Presence etc as Catholic.
I'm going to start a new thread about that. I believe Orthodox Christians agree with us that the Mass/Divine Liturgy is a Holy Sacrifice etc.