Hi Andrew,
A worked example would be a good idea. I'll try to track down Witherington again, or maybe Winter, and lay it out in detail. But before I do that, I have a few more comments.
Andrew Bowles wrote:
The only question with extra-biblical information is whether or not it is true (factual). If it is, then it should inform our interpretation of Scripture. That is not giving it 'interpretative equality' with the text, it is performing exegesis in context. If something changes on the basis of new information, it won't be the Scriptural text, it will be your interpretation, which is of course not immutable.
Firstly, Scripture distinguishes between truth that has been determined from human wisdom (Solomon's lectures for example; 2 Ki 4:29-34), and divine truth, which has been revealed in Scripture alone (Prov 30:5-6). The truth we find out from our own historical studies is not divine truth, but truth which is the fruit of human inquiry or human wisdom. When you state that the only question with extra-biblical information is whether or not it is true (factual), you're not seeing this distinction. All truth is not equal in God's economy. Special revelation alone is immutable, and capable by God's power to lead us into faith and obedience (Jn 17:17).
Once this distinction is recognized, you might be able to see the problem of depending upon extra-biblical information for the interpretation of Scripture. It brings divine truth down to the level of human wisdom; or, it brings human wisdom up to the level of divine truth.
There is a relationship between divine and human truth. God took the rational inquiry of Luke the evangelist for example (Luke 1:1-4), and infused it with his own divine breath. But there is an absolute difference between divine truth and human wisdom at the point of authority. God's Words alone have authority to bind the conscience.
You've also raised the issue of interpretation. Human interpretations of divine truth are mutable to be sure. It is of course possible that extra-biblical background information will challenge a presupposition that underlies a particular interpretation, and lead to a better interpretation which is actually what the biblical text meant in the first place. I agree with you on that.
However, my contention is that though this happens, Scripture is actually sufficient anyway, so that one could have arrived at a better interpretation based on information given in Scripture alone, and that it is not necessary for the church, or individuals, to rely on extra-biblical historical information in order to understand God's Words enough to trust and obey him fully.
In the next post, I'll try to get down to an actual example.
In Christ,
Jordan