I don't see how these disparate, disconnected ideas "defend" the man-made doctrine of Sola Scriptura. Section I affirms the value of Sacred Scripture (which I don't think anybody is arguing against) and Section II warns against doing a bunch of stuff that generally nobody is doing.
It's interesting because Sola Scriptura is allegedly this bulletproof, unassailably obvious doctrine and yet nobody can find a passage from Sacred Scripture saying words to the effect of "Sacred Scripture is the only source the faithful should use".
Typically, adherents of Sola Scriptura write War & Peace-length posts replete with flow charts and faulty logic arguing in circles about how wonderful Sacred Scripture is (which nobody questions) but never a decisive quote from Sacred Scripture (which the great majority of the Christian world questions).
If I may jump in here for a moment without reading all the previous exchanges, the premise that under SS something must explicitly stated in order to be Scriptural is simply a straw man, and thus your argument is invalid insofar as resting upon that premise.
Using the Westminster Confession as a historical authority, it plainly states that what is "necessary for God's own glory, man's salvation, faith, and life, is either expressly set down in scripture, or by good and necessary consequence may be deduced from scripture:"
To which it adds that souls by "a due use of the ordinary means, may attain unto a sufficient understanding of them" (necessary things). And also that ."we acknowledge...that there are some circumstances concerning the worship of God, and government of the Church, common to human actions and societies, which are to be ordered by the light of nature , and Christian prudence, according to the general rules of the Word, which are always to be observed.”
Chapter I
Among other examples, Christ showed the Pharisees how it can be deduced that the Messiah was not merely a son of David in the light of the fact that David called Him Lord. (Matthew 22:41-46) Likewise we can deduce that God is not an absolute unity in the light of the demonstrable facts that Christ and the Spirit are persons, and take part in creative activity (which angels nowhere are down to do), and possess other uniquely Divine attributes, and Christ is explicitly called God.
Less substantively, we do not have any clear statement that the practice of consensual
endocannibalism is wrong, but based upon what God contextually said was food for man, (Genesis 9:1-6) and that cannibalism is only spoken of negatively, then have a sound basis for condemning it as a practice.
As for the basis for the deducement that SS is Scriptural , first, it is indisputable that God manifestly made writing His most-reliable means of long-term preservation. (Exodus 17:14; 34:1,27; Deuteronomy 10:4; 17:18; 27:3,8; 31:24; Joshua 1:8; 2 Chronicles 34:15,18-19, 30-31) Psalm 19:7-11; 119; John 20:31; Acts 17:11; Revelation 1:1; 20:12, 15; Matthew 4:5-7; 22:29; Luke 24:44,45; Acts 17:11)
And thus, contrary to Catholicism, as written, Scripture became the transcendent supreme standard for obedience and testing and establishing truth claims as the wholly Divinely inspired and assured, Word of God. As is
abundantly evidenced.
Thus the veracity of even apostolic oral preaching could be subject to testing by Scripture, (Acts 17:11) and the church began with the Lord and His disciples establishing Truth claims upon Scriptural substantiation in word and in power, in dissent from the valid historical magisterium, and stewards of expressed Divine revelation.
Therefore at the very least the unique sola prima authority is established, contrary to the novel and unScriptural self-proclaimed premise of ensured perpetual magisterial infallibility as per Rome (and basically in primary cults), in which the real basis for assurance of what is to be believed is based upon that premise. Thus, "...the mere fact that the Church teaches the doctrine of the Assumption as definitely true is a guarantee that it is true." - Karl Keating, founder of Catholic Answers; Catholicism and Fundamentalism San Francisco: Ignatius, 1988, p. 275),
For Rome has presumed to infallibly declare she is and will be perpetually infallible whenever she speaks in accordance with her (scope and subject-based) formula, which means her declaration that she is infallible, is infallible, as well as all else she accordingly declares.
There is also the argument that what Catholicism decrees to be apostolic truth in the form of oral tradition is a necessary supplement to Scripture, as part of being led into all Truth by additional, extra-Scriptural revelation being decreed.
However, while even the veracity of even apostolic oral preaching could be subject to testing by Scripture, yet men such as the apostles could speak as wholly inspired of God, and also provide new public revelation thereby, neither of Catholic popes and councils do or claim to do. Our assurance now that something from oral or written transmission is part of the word of God which God wants us to know, such as the names of the two men who opposed Moses, (2 Timothy 3:8) is by the record of them in wholly inspired Scripture.
In addition, while Divine Truths can be passed down, and some (not all) of Scripture is that of Truth that was passed down, this does not mean they were spoken under Divine inspiration as Scripture was penned by. The pagan prophet quoted by Paul (Acts 17) did express an infallible statement, but he was not writing as a wholly inspired writer.
Moreover, not only is written God's chosen means of preservation, but it allows for recasting and or expansion (or contraction in duplicate accounts) of what even the Lord Himself and others said (as seen by comparing duplicate accounts) in providing a more suitable as well as overall a fuller complimentary and conflative revelation than only simply recording verbatim words.
Secondly, having established the primacy aspect of SS in support for the deducement of SS, we have the sufficiency aspect of SS. Which can not be restricted to simply referring to what Scripture formally or explicitly reveals, such as how one can receive forgiveness of sins, (Acts 10:36-43) but is also must include what Scripture materially provides for, from reason, to reading, to discernment to conciliar judgments, to the basis for which and to hermeneutical principles, etc.
We do not see the different classes of literary genres explicitly stated, but Scripture makes it clear that such exist (and that historical accounts are to be taken literally, as the NT does of such in the OT, contrary to what
abounds in RC Bible scholarship ).
Likewise, Scripture provides for both men of God and a body of wholly inspired-of-God writings to be discerned and established as authoritative (essentially due to their unique enduring Divine qualities and attestation), and thus the Lord and His disciples could appeal to writings of a body of these in establishing the prophetic and doctrinal foundation of the NT church and kingdom of God. (Luke 24:27,44,45; Acts 17:2; 18:28)
Therefore, contrary to Catholic claims, the establishment of a canon, affirming as well as reproving tradition, is not inconsistent with SS. But the premise that faith in a (self-proclaimed) infallible church is essential for ascertaining which writings are of God is not valid, nor is the premise of ensured perpetual magisterial infallibility itself.
Then there is the argument that magisterial infallibility is the only effective means of unity, which Catholicism examples, and without it then anarchy must reign, which Protestantism examples. However, this is based upon the false premise that what a church officially says is the basis for determining what it believes, but which is not the Scriptural basis, which instead is based on what one does and effects, (James 2:18; Matthew 7:20) for what we choose to do manifests what we truly believe (at least at the moment).
And the reality is that rather than holding Scripture to be the wholly inspired and accurate and thus authoritative word of God, overall those who most strongly affirm this
testify to being the most unified (in conservative Biblical beliefs) major religious body here , far more than Catholics, and much show it, and thus are treated the most potent religious force by both liberals and trad. RCs alike. Despite their differences, most of which should not be.
Meanwhile, having a central magisterium - which should be a goal but not as in sola ecclesia (SE) Rome with her fantasy of ensured veracity and thus require assent of faith on that basis - does not solve the problem of variant interpretations. For the interpretive body is itself subject to interpretation, and indeed, V2 has even resulted in Catholics being more divided. Division in Catholicism consists both of things which RCs can validly disagree one, as well as variant opinions that what Rome implicitly sanctions.
For in showing what she partly believes, Rome treats most everyone as church members, from liberal proabortion, prohomosexual public figures to cultic traditionalists (though it is a class of which who are the ones said to be in formal schism).
Thus there is division both under sola ecclesia and SS, but the NT church did not begin under the novel and unScriptural premise of ensured perpetual magisterial infallibility, but upon
Scriptural substantiation in word and in power. And with men speaking as well as writing as wholly inspired of God, in contrast to Catholic popes and prelates who presume to decree what the word of God is, and require implicit assent to it.
The NT church saw its limited unity under manifest men of God, in purity, probity, power and passion, which we much miss today, while Rome's so-called apostolic successors fail of their qualifications and credentials (as do I). (Acts 1:21,22; 1Cor. 9:1; Gal. 1:11,12; 2Cor. 6:1-0; 12:12)
Now that was exhausting for me to write, thanks be to God.