1. On Augustine:
You quote Augustine as saying:
"I would not believe the Gospels themselves, had not the Catholic Church recommended them to me"
But Augustine also once said this:
"God alone swears securely, because He alone is infallible." See Augustin on Psalm 89
So whatever Augustine meant regarding his movement to the Gospel by the church, he did not, apparently, draw a connection between that and the much later evolved doctrine of ecclesiastical infallibility. Based on his ability to distinguish between creature and Creator, it seems reasonable he would reject infallibility as a property of any human gathering.
Furthermore, Luther and others dispute whether, in the quote you cite, Augustine was referring to the teaching authority of the Roman See, or whether, more like Ignatius, he was simply referring to the universal congregation of Christ followers as the source of this recommendation of the Gospel.
Furthermore, it has been observed that Augustine is not commending the authority of the church as something he was blindly obliged to obey, but rather that he came to consider the Gospel because the church influenced or stimulated him to investigate it.
From this we can see, as you have observed, that it is helpful to carefully study the use of terms in context, to try and understand them in the most accurate way possible. Unfortunately, for every one of us that reminds others of this principle, it applies equally well to ourselves. Which is why these conversations must be saturated in God's grace, which we all need, because we are all fallible, and those of us who purport to teach others will have the greater judgment. Something to remember.
2. Qualitative Sufficiency.
I observe in your posts a tendency to use the ongoing production of Scripture over time as an argument against "coverage" of the Biblical evidence for Sola Scriptura. I believe this is an error in understanding what Sola Scriptura is, as a formal teaching. The principle of SS does not require that the full extent of Scripture be known. This may surprise you but it is true. SS is a qualitative, not a quantitative assessment. It is in the nature or quality of God communicating with us, in words, that we find His communication sufficient to the purpose He intends for it.
At this point you might suggest I am blurring the line between formal and material sufficiency. Indeed I am, and with deliberation. There is a sense in which the two very closely related categories have been artificially separated for polemical purposes, but I find what holds them together greater than what distinguishes them. Consider for example the cruel fiction of giving a starving person a text that contains every fact necessary to create a wonderful meal, but the poor soul doesn't have his johnny quest decoder ring, and starves to death anyway because he cannot read the encrypted text.
Put another way, a text that was preemptively encrypted would not have material sufficiency to the person who could not read it. No amount of reading would provide the reader with any information they could use. Whether to believe in Christ or reject Him is not even the question. The poor reader can't get so far as to determine whether anything is being said at all, or whether the words were randomly generated by a mindless computer.
Does the Scripture's self-description concerning it's God-breathed nature come anywhere close to that nonsense? Not at all. You can parse away at scope all you like, and that seems to have been your main defense against the obvious. But in fact a young man who feeds on every word that proceeds from the mouth of God will indeed cleanse his ways, and will find his spiritual life sustained by it, and will find, as Paul told Timothy, that everything they need to come to Christ and live for Christ is not only there, but not encrypted at all to the believing heart, and even capable of convicting the unbelieving heart, for the clarity of its message. This is what God's word says about God's word. It's the quality, not the quantity.
3. About Circles in Epistemological Logic.
You have critiqued this axiomatic approach to understanding the supreme authority of Scripture as the a priori application of Protestant definitions in order to come up with Protestant conclusions. I do not believe that is correct (and if I have not represented your view correctly, please feel free to correct me). But I would point out that the escape from circularity in any argument is non-trivial, and Roman epistemology is fraught with far more puzzling circles than the evangelical solution.
To be clear then, we hold that God exists, and that He is a rewarder of those that diligently seek Him. Are we still on the same page? Or are these uniquely Protestant propositions? Moving on, we hold that it is not Protestant, or Catholic, but just generically Christian, to believe the following:
3. That God is love, and so is actively seeking reconciliation with lost sinners,
4. That to do so He communicates with them for the purpose of directing them to believe in Him, and specifically to believe in Jesus, so that they will be saved.
5. That as God, He has a perfect ability to communicate with any human, and is limited only by His own purpose.
6. That according to His purpose, He may reveal His Messiah to Peter and hide Him from Caiphas, at His sole discretion,
7. That Scripture does indeed testify to the superiority of the words of God in discerning the mind of God,
8. That even if Scripture did NOT explicitly declare its own qualitative superiority, such would be implicit in the nature of divine purpose and communication.
9. That God created the world and therefore the entire infrastructure of human processes of thought and communication,
10. That as a result the communication of God by design must be intelligible, else one is accusing God of either irrationality or incompetence or cruelty,
11. That therefore if God communicates at all, it is necessarily sufficient for His purposes, and necessarily intelligible to the audience to whom He is speaking.
Thus both the material and formal sufficiency of Scripture are reasonable and proper inferences from data both you and I hold in common, which inferences are confirmed in many places by Scripture's self-attestation.
What about oral transmission of divine truth? Certainly Paul was justified in expecting compliance with his oral teaching, as he was an apostle after all. Paul never confirms the perpetuation of an oral tradition not traceable to known apostolic teaching. One cannot simply pull a new tradition out of a magic hat and proclaim it sacred by fiat. That requires a different principle, a presumption of authority in the magic hat, which if the hat cannot produce it, why should anyone choose the hat over the indisputable record of God's own words?
Peace,
SR
Thanks for the quality input.
a young man who feeds on every word that proceeds from the mouth of God will indeed cleanse his ways, and will find his spiritual life sustained by it, and will find, as Paul told Timothy, that everything they need to come to Christ and live for Christ is not only there, but not encrypted at all to the believing heart, and even capable of convicting the unbelieving heart, for the clarity of its message. This is what God's word says about God's word.
The manual is sufficient to function as the only wholly inspired rule, thus being the supreme judge, and is sufficient in formally providing Divine Truth, which clear Truth one may (not necessarily will) be saved and grow in grace by reading it alone
However, while sufficient in providing the necessary Truth, SS cannot mean it formally provides the preacher whose preaching may by God's grace, instrumentally convict and converts, and which "breaks down the hay" for the sheep, but which it materially provides for.
For everything from the ability to reason, the ability to communicate, to discern literary genres, the interaction needed to learn to love others, situations needed to learn how overcome temptation, and other things that are part of growing in grace require things which Scripture materially provides (by way of sanction, and in principle etc.)
And for salvation and growth in grace the church instrumentally uses the only wholly God-inspired substantive and sufficient body of Truth there is for doctrine, for reproof, for correction, for instruction in righteousness: That the man of God may be perfect, throughly furnished unto all good works. (2 Timothy 3:16-17) Thanks be to God.
Thus the formal and material aspects need to be explained. You have RCs who think SS must mean Scripture alone provides everything, and or that only Scripture can be used in determining doctrine, perhaps because some SS defenders sound like that.
What is not essential, and can actually be harmful, are extrascriptural and unscriptural traditions which are held as equal with Scripture by the supreme authority of the infallible magisterium. Which itself comes from the oral tradition that it elevates.
Under that model the flock is to implicitly render assent of faith to whatever the supreme magisterium decrees, under the premise of her self-proclaimed but novel and unScriptural premise of ensured perpetual magisterial infallibility. But while both ecclesiastical and civil magistrates are to be generally obeyed as the highest judicial authorities of men, yet they are not the supreme infallible authorities on Truth. To hold that being the magisterial stewards of Scripture means such are infallible is to nuke the church.
It's the quality, not the quantity.
But while Scripture was the supreme rule and sufficient to save and grow in grace to a degree even under the Law alone - understanding it as God illumines as the psalmists extol - it is was not sufficient to provide all the Truth for the Christian until its the final book was inscripturated.