It looks to me as though your questions about the first three items do not specifically relate to interpretation. Even if it was completely ambiguous as to what books to highlight, these principles would still be valid, just as they are to any secular collections or what not. I am not saying that your questions are unreasonable questions, only pointing out that they do not change the validity and usefulness of the principles.
However, your questions also give me an opportunity to make sure that everyone understands that the NT
is a collection of various documents and not one unified writing. So, very often we think about 'external' evidence for the Bible as though because it is all in one book for our convenience the various books in it are not independant entities of their own. In otherwords, you can get external corroboration of Matthew by looking to Luke.
Some think that is a copout, but it is a plain and obvious fact. If it was argued that something like Tacitus' Annals were a real external source, in order to prove my point imagine if we decided to bundle every single ancient document into
one single book. Does Tacitus or any other document cease to become an external source because it happens to be bound together in one anthology for our convenience?
I know that you are not arguing otherwise, I'm just using your post as an opportunity to point out that we could add another set of principles that pertain to interpreting a passage. First you look at the context of the passage within its own limits, ie, you'd look for internal evidence. Looking towards other books of the NT for help in interpreting the documents in the collection is an obvious next step, but in doing so, technically it is external evidence.
Now, what about how these documents were selected? This was not an arbitrary thing and the history of the canonization of the NT is really a history of RECOGNIZING authorized works in the midst of the Christian community rather then endowing upon them that authority.
There was a basic criteria: 1. the documents had to have been written by an apostle or one with apostolic authority. 2. The documents had to have had wide use in the Christian church. 3. The documents needed to have a solid textual tradition at the congregation presenting it. 4. And the documents needed to agree with what had been received orally.
1. Some very good documents like the Sheperd of Hermes were excluded from the canon because they were not written with apostolic authority. This is very wise. It means that the norm for the doctrine in the community would rest primarily on the actual teachings of those who first received them. One should expect it to go without saying that those actually sent out by Jesus personally should have the highest levels of credibility possible for the transmission of 'true Christianity.'
2. If a work was highly favored in one church but no other church used it, it was rightly doubted. Worthy documents were spread throughout the Christian church. If the document was really worthy, the majority of the Christian church will have recognized it.
3. Very much like the papist succession, there was some concern about carefully transmitting documents from one generation to the next. A document that appeared suddenly in the second century written allegedly by some apostle was not going to be trusted. In theory the document could have been really written by an apostle. But if so, where was it for 150 years and why hadn't any of the other churches heard about it?
4. The canon didn't come into fully delineanted until about 350 AD but that doesn't mean that it wasn't being outlined far earlier. The four Gospels, for example, appear to have been eleveated above all others that were in circulation by 130 AD. And Paul's letters had also gained prominence. Certain books, like 2 Peter or 2 or 3 John took longer to be trusted. But the point is that these documents had already achieved wide circulation.
For example, one of our earliest fragments, the Rylands Fragment, is a piece of John dated about 120ish AD. It was found in Egypt and scholars believe that the copy really originated from there. Though it isn't geographically far, it shows that these documents were already moving far and wide WITHIN THE LIFETIME OF THE SECOND GENERATION CHRISTIANS.
The Apostle John, for example, taught Ignatius, who taught Polycarp. And we have some writings of Ignatius. Five letters, I think. In otherwords, right alongside the transmission of the written documents there was oral transmission, as well. There was real effort and real pride within the churches to say that they had been founded by an Apostle and had a clear transmission of authority (this came to a head with the rise of the church of Rome and the papacy).
However, it would not be reasonable to expect this oral transmission to last accurately for a long time. At least, it would be difficult, obviously, to authenticate an oral transmission, after, say 1,000 years. So, it is really natural that the oral transmission would have been used as a final check and balance on the documents recognized as authoritative, but then allowed to fade away, allowing the documents themselves to become the source for the final word.
The canon was probably actually done by about 250 AD (ish) but it took the Christianizing of the Empire under Constantine for it to be ratified by all the churches. Remember that before this, such a ratification wasn't really possible. Since Claudius (c. 50 AD), Christians had been persecuted, and this lasted right up to Constantine (c. 310 AD). It really wasn't in their best interest to gather together in one spot, you understand. Even after this there were some Roman emporers that turned against the Christian church.
Interesting note: The high value that Christians had placed on the Scriptures was in fact very well known by the Romans from early on. When Romans arrested or threatened Christians, they always came after the sacred documents, as well, recognizing their power within that community. Christians that turned over the documents were called 'turner-overs,' or, in Latin, 'traditor,' our 'traitor.'
http://www.thefreedictionary.com/TraditorI'd suggest reading Bruce Metzger's "The Canon of the NT" and check out
www.ntcanon.org for some good raw material.