I’m not sure what you mean by the question. Catholics, as far as I know, do not hold that the Church is SOLE authority, but that Scripture is authoritative as well. Church teaching and expounding of that authoritative and infallible Scripture is also authoritative and infallible.
I understand that many modern day members of the Roman communion, especially their "apologists," reject the charge of
sola ecclesia, but I don't think they can effectively answer that charge. If the magisterium (their term for church) is the judge both of tradition and of Scripture, then how can it be otherwise than
sola ecclesia? Many of their own theologians and members of their magisterium affirm this description. Notice the following citations from the following Roman cardinals...
Cardinal Archbishop of Westminster, Henry Edward Manning (1808-1892): It was the charge of the Reformers that the Catholic doctrines were not primitive, and their pretension was to revert to antiquity. But the appeal to antiquity is both a treason and a heresy. It is a treason because it rejects the Divine voice of the Church at
this hour, and a heresy because it denies that voice to be Divine. How can we know what antiquity was except through the Church? No individual, no number of individuals can go back through eighteen hundred years to reach the doctrines of antiquity. We may say with the woman of Samaria, ‘Sir, the well is deep, and thou hast nothing to draw with.’ No individual mind now has contact with the revelation of the Pentecost,
except through the Church. Historical evidence and biblical criticism are human after all, and amount to no more than opinion, probability, human judgment, human tradition.
It is not enough that the fountain of our faith be Divine. It is necessary that the channel be divinely constituted and preserved. But in the second chapter we have seen that the Church contains the fountain of faith in itself, and is not only the channel divinely created and sustained, but the very presence of the spring-head of the water of life, ever fresh and ever flowing in all ages of the world. I may say in strict truth that the Church has no antiquity. It rests upon its own supernatural and perpetual consciousness. Its past is present with it, for both are one to a mind which is immutable. Primitive and modern are predicates, not of truth, but of ourselves. The Church is always primitive and always modern at one and the same time; and alone can expound its own mind, as an individual can declare his own thoughts. ‘For what man knoweth the things of a man, but the spirit of a man that is in him? So the things also that are of God no man knoweth, but the Spirit of God.’
The only Divine evidence to us of what was primitive is the witness and voice of the Church at this hour. Henry Edward Manning,
The Temporal Mission of the Holy Ghost: Or Reason and Revelation (New York: J.P. Kenedy & Sons, originally written 1865, reprinted with no date), pp. 227-228.
Cardinal Manning's words above are a declaration of
sola ecclesia with a vengeance. And then, speaking of the difficulty of the so-called Unanimous patristic consent as a reliable
locus theologicus in Catholic theology,
Cardinal Congar wrote: “Application of the principle is difficult, at least at a certain level. In regard to individual texts of Scripture total patristic consensus is unnecessary: quite often, that which is appealed to as sufficient for dogmatic points does not go beyond what is encountered in the interpretation of many texts. But it does sometimes happen that some Fathers understood a passage in a way which does not agree with later Church teaching. One example: the interpretation of Peter’s confession in Matthew 16.16-19. Except at Rome, this passage was not applied by the Fathers to the papal primacy; they worked out exegesis at the level of their own ecclesiological thought, more anthropological and spiritual than judicial. . . . Historical documentation is at the factual level; it must leave room for a judgment made not in the light of the documentary evidence alone, but of the Church's faith.” Yves M.-J. Congar,
Tradition and Traditions: An Historical and a Theological Essay (London: Burns & Oats, 1966), pp. 398-399.
And then
Cardinal Congar even goes on to insist “It is the Church, not the Fathers, the consensus of the Church in submission to its Saviour which is the sufficient rule of our Christianity.” Yves M.-J. Congar,
Tradition and Traditions: An Historical and a Theological Essay (London: Burns & Oats, 1966), p. 399.
When members of the Roman communion are willing to be honest, then they must admit, in the end, their submission to the principle of
sola ecclesia.
Neither the principle of
sola ecclesia nor
sola scriptura mean that the church or scripture are sole authorities. What is meant by each is this;
Sola ecclesia means that the church is the
sole ultimate, infallible authority (i.e. from a Roman perspective), whereas
sola scriptura means that Holy Scripture is the
sole ultimate, infallible authority. Albeit Protestants deny their communion to be infallible. In a Roman apologist's rejection of the description of
sola ecclesia, he cannot be honest with his own system of belief.
