Kaik: I love Midrash and I had a borrowed copy, but it was too extensive to read.
Yes! I understand your feelings. But it is interesting to see what this alternative stream of Biblical tradition, thought about the problems raised by the documents that were selected to be canonical.
As you rightly pointed out, the Jewish interpretations were transferred into Christianity via Christian readers of the Midrash in later times.
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Interpretations (targums, midrash and pesher) and authoritativeness
Dunn, whose book (Unity and Diversity in the New Testament) I'm using as a base for my comments, when discussing midrash, refers to the differences between the Sadducees and the Pharisees over the usefulness of tradition (p.66,67). The Pharisees (much as the Catholic church also does), understood that Torah consisted of both written (the Pentateuch) and unwritten (oral) works. The Sadduccees (as, I'm sure most readers already know) only accepted the written Torah as authoritative. Dunn explains why the Pharisees took the above stand. It was because the Pharisees recognised that no written law cover all the exigencies of a changing culture, and therefore the written Torah had to be continually interpreted and supplemented. So if the tradition (probably no longer merely oral, but necessarily written) was regarded as a justifiable interpretation of the written Torah then it became part of the Torah and authoritative. The Sadducees however, could not/would not see it that way.
(Note: Josephus explains his view of the Sadducee/Pharisee argument in his Antiquities XIII.x6 - a web copy can be found at:
http://sacred-texts.com/jud/josephus/#aoj )
Those of us who took the JW biblical attitudes seriously will easily see how interpretations can and must change as circumstances and the problems that arise as interpretation impacts on authority.
As an example, the problems associated with the JW version of midrash are well-known in the JW policy on blood. We can ask, did the policy as originally stated, cover all the positions allowable under Bible usage? Likely not. So we saw changes to the original, maybe similar to what may have happened in example of Jewish discussion. If you'd like to see a modern day, non-witness discussion on a related topic on the use of blood, check out this essay:
(Religious perspectives on umbilical cord blood banking
Link: http://www.vifm.org/wp-content/uploads/2012/01/Jordens.pdf )Even the form of interpretation had to defined. Eventually, interpretation took two forms - Halakah and Haggadah became defined.
Halakah was a specific declaration of God's will in a particular case, a rule of right conduct to guide the inquirer in the way he should go. Over time a considerable case law developed covering the whole of practical life and dealing inclusively with civil, criminal and religious aspects. The Halakah is what the authors of Matthew and Mark refer to as, 'the tradition of the elders,' and was a process well under way before 70 CE. The rules of Halakah were what the gospel writers have Jesus objecting to when he sets the 'tradition of the elders' against the 'commandment of God.'
Haggadah was different. Essentially it was an interpretation designed to edify the hearer/reader, and not necessarily to regulate conduct. It aimed at inducing piety and devotion in its audience.
In any contemporary Christian church we can read or hear similar things, but the witnesses seem to excel, and modern day audiences may find it all very legalistic and controlling.