The evangelical doctrine of Biblical inerrancy claims that the books of the Bible were without error "in the autographs", that is, in the originals. The idea is that when David or Moses or Luke or Paul put "pen" to "paper", God guided the process so that nothing untrue was written down.
In an earlier post, I talked about the fact that, since we are so far (historically) from having the autographs, this claim is meaningless. Pointing to an unknowable document is of no use at all. The doctrine of inerrancy does little more than to 1) serve as a test of faithfulness and 2) provide a vaguely defined foundation to excerise authority over others ("You're not arguing with me, but with God's Perfect Word".)
But there is more to it than that.
When it comes to Paul's letters to the Romans or the Philippians, I can at least imagine what the "original manuscript" might be. After all, both of these are epistles which seem to be the work of one author. It's possible to conceive of the author writing the whole document in one or two sittings. The final product is the autograph, the original copy, the one evangelicals claim was without error.
But when it comes to the Gospels, for example, things are more complicated. In Luke, the author (who doesn't sign a name) says that "many have undertaken to compile an account of the things accomplished among us, just as they were handed down to us by those who from the beginning were eyewitnesses and servants of the word" and claims to have "investigated everything carefully" before writing a new, orderly account. (I recently heard a Bible scholar sum up Luke's prologue as "You've read the rest, now read the best!")
If Luke did research - if he talked to eyewitnesses (or those who talked to eyewitnesses), if he used sources (he seems to have used Mark, and he may have used Matthew or else another sayings source that has been lost to history - and he may have looked at the "many" accounts he mentions) - then it's a bit more blurry as to what was the original manuscript. Was it the sources he used, or the testimony he heard from others? Was it the oral stories that were passed around? Was it his notes? His first draft? Just the final draft?
The problem is even more apparent in the Old Testament. The books of Psalms and Proverbs are clearly collections of writings and sayings from many sources (often anonymous). The stories in the Pentateuch often bear the marks of being edited together from different versions, and at a much later time than when the events are said to occur.
None of this is unusual, nor is it particularly controversial, even among evangelical Bible scholars. But it leads me to think that the "original manuscripts" are mythical creatures, impossible to define in many cases. They exist in the mind because the believer needs them to exist.