Session six of the Second Council of Nicea 2 has an interesting discussion of what is required for a council to be truly ecumenical:
It [the Council of Hiera] did not enjoy the cooperation [lit. ουνέργεια] of the then Pope of Rome or his priests, neither by means of his representatives or an encyclical letter, as is the rule for councils; nor did it win the assent [lit. ουμφρονοῦντας] of the patriarchs of the east, of Alexandria, Antioch, and the holy city, or of their priests and bishops…Nor did ‘their voice’, like that of the apostles, ‘go out into the whole earth or their words to the ends of the world’, as did those of the six holy ecumenical councils. (Price, p. 442)
The preceding definition is important because it delineates the differences between Rome and the rest of the Pentarchy. A true ecumenical council does not require Rome’s “assent” (as Father Price translates the term), but rather their “cooperation.” The Greek word for “cooperation” (ουνέργεια) is a generalized word that literally translates to “energy” or “activity.” “ουμφρονοῦντας” is a word for “partisans” or “to be minded of.” The latter Greek term is more powerful, and implies a powerful faculty of thought that conceptualizes an issue. In other words, the passive cooperation of Rome is needed while hands-on, unconditional assent (hence, to be a partisan) is required of the rest of the Pentarchy. As Price notes in Footnote 58 on the same page:
As noted by Schatz (1987) 266, a distinction is made between the ουνέργεια or ‘cooperation’ of the Roman see and the ‘assent’ (ουμφρονοῦντας) of the oriental patriarchs. In fact, during the sessions of Nicaea II one of the oriental representatives, John the synkellos, played a more prominent role than either the Roman representatives.
Rome’s “cooperation” historically has proven to be indirect (through legates) or extremely indirect (vague, retroactive approvals). So, while Rome merely sent legates to some councils (Nicea I, Constantinople III, and Nicea II) it did not to others (Constantinople I and Constantinople II). Saint Cyril of Alexandria during the Council of Ephesus considered the council’s work binding before the Roman legates’ arrived, so it is sort of a cross between the preceding, the legates retroactively approving the work of the council they had not attended and approving its status as ecumenical retroactively at a later session.
Some of the historical details surrounding the councils with the most indirect Roman participation are quite illustrative. For example, while Constantinople I had some element of Roman participation though the Bishop of Thessalonica, Saint Ascholius. In fact, the Pope sent a letter to this effect. Yet, Saint Ambrose indicated in Letters 12 and 13 that his participation was not automatically accepted by the western Bishops, including the Pope (who maybe now had buyer’s remorse), as adequately representing them. They wanted eastern legates to finalize things in a council in the West. The Council replied with a synodical letter flatly refusing. Despite all of this, the Papacy as well as the rest of the West accepted the Creed and Canons of this council. One may perceive how Rome’s “cooperation” was inferred and justified by Rome’s tacit acceptance of the council, though without much fanfare.
Constantinople II takes the historian a little more digging in discerning how it met the criteria of Nicea II as laid out above. Unlike any other ecumenical council, the Pope (Vigilius) was actually “in town” and was supposed to attend. Instead of playing some chief role in presiding over the council, he was in opposition to it the whole time it was in session. He had in effect held a counter-council in penning the First Constitutim and disputed Constantinople II’s premises, with the intent of making this Rome’s (and other western Bishoprics) official position to the whole world. So, no legates of his attended Constantinople II.
In response, the council had in fact “excommunicated” him in its seventh session, as evidenced by his title as Bishop not being used and his name being removed from the diptychs (more formal excommunications occurred to Nestorius and Dioscorus in the two preceding councils, the fifth council merely deposing Vigilius for heresy but not for failing to answer three summons–likely for the reason that if he recanted his restoration would be much easier).
With the preceding taken into account, precisely how did the Pope “cooperate” during the fifth council so as to make it legitimate? It was either “by means of his representatives or an encyclical letter, as is the rule for councils.” One can discount the former criteria, because Vigilius did not send legates. So, the latter (“an encyclical letter”) is the means the Pope cooperated.
The seventh session of the council asserted that the Pope had pre-emptively cooperated despite his lack of cooperation in the present, citing an array of documents to this effect:
[A] brief and formal condemnation of the Three Chapters [from Vigilius], written in 547 to satisfy Justinian and not hitherto made public, a virtually identical document written for the empress Theodora, a long letter from Vigilius to his former deacons Rusticus and Sebastian, depriving them of their office as a penalty for the campaign they had been conducting…to undermine his authority and oppose his Iudicatum of 11 April 548 [a conciliar document], in which had condemned the Three Chapters, a letter from Vigilius to Bishop Valentinus of Tomi [about the Iudicatum]…, a similar letter from Vigilius to Bishop Aurelian of Arles…, the text of an oath taken by Vigilius on 15 August 550 and hitherto kept secret in which he had promised to cooperate with the emperor in securing the condemnation of the three chapters. (Price, Constantinople II, Vol 2, p. 72-73)
One can surmise that the preceding documents missed the mark of actual cooperation or an encyclical to that effect, with perhaps the exception of the Iudicatum. In any event, Constantinople II took the preceding as proof the Pope had approved of their work, condemned the Three Chapters (Nestorianism) in its eighth and final session, and otherwise asserted the necessity of conciliarity (over an against Vigilius’ claims in the First Constitutim that he had settled the matter himself in favor of the Three Chapters). Vigilius, due to his continued house arrest (and likely fear of losing his job due to his deposition, see Ibid., p. 214), wrote a letter to Eutychius of Constantinople recanting his previous position, affirming the canons of the council (Ibid.), and asserting that “we…are in agreement over the one faith” (Ibid., p. 215) This would have been sufficient retroactive cooperation with the council, but the audience was not wide enough due to it being specifically to one bishop. The letter would not properly be understood as an encyclical.
The Second Constitutim corrected this and reiterated what was stated in the letter to Eutychius, but in far more detail. The canons in Session VIII were affirmed in order, (Ibid., see Footnote 4) demonstrating that Vigilius approved of the decree of the council (which had, in effect, condemned him and upheld conciliarity). Just as the First Constitutim was directed to the whole Church against the council, the Second Constitutim was likewise directed to the whole Church in favor of it.
And so, Nicea II gave a realistic, historical criteria for what constitutes an ecumenical council. Rome does not have to affirm every jot and tittle of a council for it to be truly ecumenical. In fact, they could oppose a council while it is happening. Historically, “cooperation” can simply mean affirming the ecumenical council’s canons. This sufficed in lieu of Rome’s unconditional assent in every respect. In this way, Constantinople I and II, which had conditional Roman acceptance only after the time of the council (especially in the latter case), were in fact legitimate councils. Even Chalcedon, in which Rome would not affirm all of the council’s canons (specifically the 28th), confirmed this principle. The fact Rome in some official capacity cooperated with the council (in most respects) sufficed for the council to be official. Their full assent was not necessary for Canon 28 to be perceived as legitimate (and ironically, only after the Great Schism would Rome come around and accept this canon).
In conclusion, the difference in Greek wording as to what is required of Rome and the rest of the Pentarchy interestingly makes Rome of secondary importance when it comes to the work of an ecumenical council. The see’s full assent is not even required, according to the definition. However, to the chagrin of many Orthodox, the Orthodox Church today (though they can still have binding Pan-Orthodox Synods) cannot have an ecumenical council without the Pope of Rome.
In any event, one may readily perceive that the answers to these issues which history provides is often inconvenient to most people’s preconceptions. That is not always bad. It makes things more fun.