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Sola Scriptura: The Definition
The Rule of Scripture is the practice of embracing Scripture as the rule ("straight edge") - canon ("measuring stick") - norma normans (the norm that norms) as it is called in epistemology, as we examine and evaluate the positions (especially doctrines) among us.
And your false assumption is that we all need to be epistemologists. That unity advances only insofar as we:
(1) All must explicitly agree that Sola Scriptura is the best epistemology, i.e, all agree that the Bible is the ideal norma normans
(2) All must proceed to put it into practice
However:
(1) This epistemology has proven itself a failure (see my post previous to this one).
(2) The Inward Witness is capable of coercing assent, and thus coercing consensus/unity, even among non-epistemologists.
Thus while Sola Scriptura is ONE possibly theory of solidarity, ANOTHER theory is that we will unify if we properly seek His Voice. When we all are hearing the same thing - especially if it's at the degree of 100% certainty - we will be unified. Since you can't seem to comprehend this concept, please don't object to it. I will just ignore your confused objections. Feel free to ask me questions about my position, and once I am satisfied you have some inkling of an understanding of it, I will then be happy to consider any objections.
You state:
Or what objective and universally embraced rule/canon/norm is best in the arbitration of correctness
But you incorrectly assume that we must EXPLICITLY embrace that epistemology. And one thing (among many) that I've been trying to tell you is that we all IMPLICITLY (tacitly) embrace the following maxim - which has epistemological ramifications!
"If I feel certain that action-A is evil, and B is good, I should opt for B."
For example, suppose you're preaching to 5,000 unbelievers. Suddenly the Spirit convicts/convinces them all that Jesus is Lord. (This is unity, this is norming). They now feel certain about it. They cry out to you, "Yes we are convinced. What shall we do next?".
You've got two basic responses:
(1) You can respond as Peter did. "Repent and be baptized for the forgiveness of your sins" (Acts 2:38).
(2) OR, you can respond, "Do NOT embrace the gospel as yet! Do NOT embrace your navel! Do not accept doctrine until you've undertaken a proper norming process as bona fide bible scholars!" This response is absurd - and immoral because it contradicts the maxim.
And even the exegete, ultimately, looks to feelings of certainty as his epistemological standard. He researches an issue in Scripture until he feels he has reached a satisfying level of certainty that his interpretation is correct. And thus, for example, if he ALREADY felt 100% certain on an issue (due to to Direct Revelation), he wouldn't research it at all.
Thus we all accept certainty as an epistemological standard, even if we are not always EXPLICTLY aware of this tacit acceptance.
Let's say Dave and Fred are neighbors. They decided that they will hire a contractor to build a brick wall on their property line, six feet tall. Dave and Fred hire Bob the Builder. He agrees to build the wall on the property line - six feet tall.
It's totally absurd for you to suggest that you can "establish" a religious epistemology merely by appealing to simplistic empirical, easily reproducible anecdotes and lab-experiments. That's like trying to resolve the history of philosophical debates by running a couple of experiments on lab rats. Seems that YOU are the one posting material that has ABSOLUTELY NOTHING TO DO with resolving the norming-problem raised on this thread.
And let's go back to your silly example of building a brick wall six feet tall. Does it culminate in norming? My Dad WAS a contractor. No matter how much he tried, the customer was never satisfied. For example he'll come back and say, "No, I meant six feet above ground level but that particular spot was already below normal ground level and therefore you needed to erect something taller." At that point it then becomes a question of whether the customer wants to sue my Dad in court - and they often did.
Norming typically involves a norm: WHAT will serve as the rule (straight edge) or canon (measuring stick) - WHAT will be embraced by all parties involved in the normative process that is the reliable standard, the plumbline.
Explicitly embraced? Or tacitly/implicitly? See above.
Why Scripture?
In epistemology (regardless of discipline), the most sound norma normans is usually regarded as the most objective, most knowable by all and alterable by none, the most universally embraced by all parties as reliable for this purpose. My degree is in physics. Our norma normans is math and repeatable, objective, laborative evidence...
Empirically verifiable math and science have ABSOLUTELY NOTHING TO DO with addressin the empirically UNVERIFIABLE questions of religion. Shall we take David as an example? On several cases he had to decide whether to go up and slaughter the Philistines. But a good man, such as David, doesn't run around murdering nations at less than 100% certainty. How was he to arrive at 100% certainty on this issue?
(1) Biblical exegesis?
(2) Or seeking the Voice?
"David enquired of the LORD, saying, Shall I go and smite these Philistines? And the LORD said unto David, Go, and smite the Philistines…Then David enquired of the LORD yet again. And the LORD answered him [again]…I will deliver the Philistines into thine hand (1Sa 23:2, 4, KJV)."
Why a second inquiry? Either the level of certainty on the first iteration was less than 100%, or was indeed so but subsequently waned. But here's the clincher. When an evangelical is unsure about a possible revelation, he says to himself, "I need to 'check it out with Scripture'". David's attitude was, "If I'm unsure about a revelation what I need to do is - seek more Direct Revelation!"