Anyways, to reduce the question of the role of Scripture and Tradition to its bare bones, here are the three things being asked:
- What role, if any, should extra-Scriptural Tradition play in guiding or controlling our interpretations of Scripture?
- Can doctrines come from extra-Scriptural Tradition, if those doctrines are not taught in Scripture?
- Can doctrines coming from extra-Scriptural Tradition be "essential"?
The major splits between different Protestant camps come on their answer to #1. Some say Tradition is binding on our interpretation of Scripture, some say it's a lens through which to view Scripture, and some say it plays little to no role at all. That's an interesting debate, but let's leave it aside, because it's irrelevant to my point. I'm more concerned about the other two questions, because on questions #2 and 3, there's near-unanimity within Protestantism that all doctrines must be derived from Scripture. It may be "Scripture as I read it," or "Scripture as read by the Church Fathers," but the outcome is the same. "No" on 2, and "no" on 3.
Of course, this is where the obvious problem comes in. Scripture doesn't have an inspired table of contents. No Book in the Catholic, Orthodox, or Protestant Bible teaches which other Books are inspired by God. Most of the Books don't even mention that they are themselves inspired, so you can't even rely on the circular "2 Peter is inspired because 2 Peter says it is, and it's inspired" argument -- because 2 Peter doesn't tell us if it's inspired or not. Nor is there anything implicit within the Scriptures.
To be clear, if God wanted us to believe in sola Scriptura, He clearly could have inspired one of the New Testament authors (St. John, for example, the last to die) to write an inspired "Table of Contents" to the canon, listing the other canonical Books, and declaring the "Table of Contents" itself canonical. But that didn't happen, as everyone knows. So no, the doctrine of the canon -- that is, the Church doctrine that says "these Books are in the Bible, and these other books aren't" -- is one derived from totally outside of Scripture itself. So the answer to Question # 2 has to be yes. If no doctrine can come from outside Scripture, you can't determine the canon. If you can't determine the canon, you can't derive any doctrines from Scripture, since you don't know which Books are Scripture.
This also answers Question # 3, for an obvious reason. If you derive all doctrines from Scripture, as Protestants claim to, the single most important question is the question of "which sources are Scripture?" All other questions, from "Was Christ God?" on down to "do works have a role in justification?" are answered in Protestantism from the canon. An incomplete canon risks incomplete doctrine; an inaccurate canon risks inaccurate doctrine. An obvious example: Mormons accept the Book of Mormon, which Catholics, Protestants, and Orthodox recognize as non-canonical and inaccurate. As a result of this faulty canon, the many faulty doctrines the Book of Mormon teaches mislead people into error. So at least one essential doctrine, essential to the faith of all Christians, is taught on the basis of Tradition alone: the canon of Scripture. So the answer to # 3 has to be yes.
Protestantism teaches "No" on Question 2, and "No" on Question 3, and is plainly wrong in doing so. Yes, doctrines can come from extra-Scriptural Tradition, even if those doctrines are not taught in Scripture; and yes, these doctrines include essential, binding ones. If that's true for the doctrine most important to Protestants (the canon of Scripture), on what basis can we possibly claim it's not true of other doctrines? Does Scripture give any indication that it will answer every essential doctrinal issue except the canon? I know of no one willing to advance this argument.
So clearly, Catholics are right that it's possible for doctrines to come from extra-Scriptural Tradition alone, and that at least one doctrine (the canon) does, and that more might. If this is true, there's no excuse for ignoring the Church Fathers. It's time for Protestantism to begin to take seriously the Catholic claim that the Church Fathers teach other essential doctrines not expressly found in Scripture.