Misunderstandings about the Canon must be answered before these questions can be. At the time of Christ, there was no single canon. There was the Law, held by all Jews, including Sadducees and (laxly) Samaritans as divinely inspired. There were the Prophets, held by Pharisees as the Word of God, but not by Sadducees. There were the Writings, held as inspirational, but not in the same standard as the Prophets. (By this tripartate division, David and Solomon were considered Prophets, so Samuel and Psalms were considered among the books of the Prophets.)
Certain of the Writings were published along with the Prophets and the Law in the Septuagint. Unlike the Palestinian Jews, the Dispersed Jews became Christians in large numbers. Thus, the Septuagint became a canon unto itself, simply because it was published as a book.
It’s not that Catholics “added” books to the Canon; it’s that Catholics never infallibly defined a canon until the Council of Trent. The modern debate about the canon revolves around what may be used to establish doctrine. Absent the doctrine of Sola Scriptura among Catholics, there was no need to define such a canon.
“The Bible” simply consisted of those books used during mass, which in turn. Several Church Fathers routinely referred to what Protestants call “apocrypha” as scripture, including to settle doctrinal disagreements among Christians. Others warned that the Jews did not regard the “apocrypha” as scripture, so it made little sense to cite the “apocrypha” as defense of Christian doctrine to Jews. Still others used “apocrypha” to describe certain books which Catholics reject as non-biblical.
Thus, there was no distinction between “oral tradition” and “scripture.” What was “scripture” was what was accepted by tradition as doctrinally correct. Thus, many books were rejected as doctrinally unsound (The “Gnostic” Gospel of Thomas, etc.), outside of the apostolic tradition (the Shepherd of Hermes), spiritually beneficial but doctrinally unnecessary (The Didache), or containing far too many local variants (most Acts of the individual Apostles).
This notion can still discerned within the ambiguities of the Council of Trent: The canon is defined as those which contain unique doctrine which must be defended. “Greek Esdras” is left in a limbo: unnecessary, since it contains virtually nothing unique, but not condemned. Psalm 151 and 3 Maccabees, commonly read at mass by the Orthodox, but lacking among Western masses, go unmentioned.
As local Traditions diverged, Scripture emerged as a test of what comprised authentic Tradition: nothing contrary to Scripture could be regarded as authentic. But this is a practice for discerning Tradition, not for subjugating Tradition as an invalid authority. Thus, we come to the authority of the Pope: where a doctrine has gone without contradiction from among the authoritative orthodox (small “o”) who have properly considered the notion, the Pope can discern that a doctrine has been Tradition, and can thus declare that the doctrine is infallible; he cannot decide that his own opinions are infallible. Nor can a Catholic in good faith contradict a doctrine of the Church simply because no pope or council has ever ruled on it.
Thus, it’s not a matter of a Pope lacking the free will to affirm a false doctrine; it’s a matter of him lacking the authority to do so. As a matter of being author of History, not as a matter of denying free will, God has affirmed that the Pope cannot with proper authority infallibly declare what is false (”Whatever you declare bound on Earth is bound in Heaven.”).
In a sense, then, the issue of whether a tradition carries authority, the answer is that it is a matter for the Church to decide as a whole (as in an ecumenical council that is approved by the Pope), or for the Pope to discern has been decided.
Nor now in Christiandom, though largely the same.
(By this tripartate division, David and Solomon were considered Prophets, so Samuel and Psalms were considered among the books of the Prophets.)
And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me. Then opened he their understanding, that they might understand the scriptures , (Luke 24:44-45)
It’s not that Catholics “added” books to the Canon; it’s that Catholics never infallibly defined a canon until the Council of Trent.
They added as infallible books that aforetime and during Trent were yet subject to scholarly dispute. You last statement, while true, many RCs find unsettling, as they see Luther as dissenting from an indisputable canon, as well a man Prots follow as a pope (which would make them rather Catholic).
Thus, there was no distinction between “oral tradition” and “scripture.” What was “scripture” was what was accepted by tradition as doctrinally correct.
Separating what was wholly inspired and authoritative, which Christ thus opened the eyes of the disciples to (which were more than the 11) from that which was not.
And as was the case before there was a church, both men and writings of God came to be est. as being so essentially due to there unique and enduring Heavenly qualities (Ps. 19; 119) and attestation, which the magisterium is to confirm, but which are such regardless. Thus the church began in dissent, with the common people recognizing what the magisterium did not/would not. (Mk. 11:27-33)
This notion can still discerned within the ambiguities of the Council of Trent: The canon is defined as those which contain unique doctrine which must be defended. “Greek Esdras” is left in a limbo: unnecessary, since it contains virtually nothing unique, but not condemned. Psalm 151 and 3 Maccabees, commonly read at mass by the Orthodox, but lacking among Western masses, go unmentioned.
Yes, unlike as against Prots, this disparity never seems to be an issue, and the Byzantine Rite is not so technical as the West. And yet there is discussion among Catholics as whether Trent infallibly closed the canon.
As local Traditions diverged, Scripture emerged as a test of what comprised authentic Tradition: nothing contrary to Scripture could be regarded as authentic.
RC Tradition cannot contradict Scripture as Rome alone is authoritative on what a contradiction is. Yet even o the EO "opposes the Roman doctrines of universal papal jurisdiction, papal infallibility, purgatory, and the Immaculate Conception precisely because they are untraditional.” - Clark Carlton, THE WAY: What Every Protestant Should Know About the Orthodox Church, 1997, p 135
Thus, we come to the authority of the Pope: where a doctrine has gone without contradiction
What teaching, or part thereof (Bulls, encyclicals, etc.) constitutes an infallible teaching is itself a matter of interpretation (as is often their meaning to some degree), with some seeing an extensive list, but usually it is a very small list. Yet "without contradiction" does not mean it is actually taught in Scripture or even that its veracity is based upon or requires weight of Scriptural substantiation, or even that the reasons or arguments upon which it may be based are infallible.
Nor on our end is he necessarily consistent with it. Its veracity rests upon the premise of the assured infalliblity of Rome. As Keating states as regards there strictly being zero proof from Scripture for it, "The mere fact that the Church teaches the doctrine of the Assumption as definitely true is a guarantee that it is true.” — Karl Keating, Catholicism and Fundamentalism (San Francisco: Ignatius, 1988), p. 275; http://www.catholic.com/tracts/immaculate-conception-and-assumption].
Thus, it’s not a matter of a Pope lacking the free will to affirm a false doctrine; it’s a matter of him lacking the authority to do so.
No one has authority to teach false doctrine, with Scripture being the assured Word of God and transcendent standard for obedience and testing and establishing truth claims, as is abundantly evidenced .
God has affirmed that the Pope cannot with proper authority infallibly declare what is false (”Whatever you declare bound on Earth is bound in Heaven.”).
That this translates into Rome's magisterial perpetual formulaic assured infallibility is an extrapolative interpretation, and which presumes this is necessary for the binding and loosing we see in Scripture, and by which Rome has presumed to infallibly declare she is and will be perpetually infallible whenever she speaks in accordance with her infallibly defined (scope and subject-based) formula, which renders her declaration that she is infallible, to be infallible, as well as all else she accordingly declares.
In a sense, then, the issue of whether a tradition carries authority, the answer is that it is a matter for the Church to decide as a whole (as in an ecumenical council that is approved by the Pope), or for the Pope to discern has been decided.
And as the latter's authority is unlimited, incalculable, and can punish every one, allows no appeal and is itself Sovereign Caprice, being subject to no one, and cannot be deposed, then it is the height of individual autocracy and interpretation.