The Ehrman Project has posted an answer to someone who asked about scribal alterations to the New Testament text. The person notes that some alterations were made to New Testament documents for theological reasons. They want to know how this squares with the claims of inerrancy.
The response begins by noting that inerrancy and inspiration only apply to the original autographs and that textual criticism can help scholars determine what those autographs looked like. The responder then suggests that theological alterations do not have any impact on the original autographs.
"If one claims that the scriptures are inerrant in the original autographs, the practice of textual criticism can help scholars determine which variants are more likely to be original and, therefore, inerrant."
The problem with this response, however, is that we do not have the original autographs and ultimately cannot be sure what they looked like. Yes, we are probably very close. But there is no guarantee that the copies of the copies we have are exactly the same as the originals. Let me give two examples both from Paul's letter to the Thessalonians.
The first comes from 1 Thessalonians 3:2 and is an example of an alteration theologically motivated. In this verse Paul calls Timothy "God's co-worker." This was a problem for some scribes, however, since they saw this as perhaps making Timothy equal to God. Thus some variants drop the reference to God, others read "God's servant" rather than "co-worker" and some have a combination of "co-worker" and "servant." All of these are attempts to alter what looked theologically improper to the scribe. And the fact is, while "God's co-worker" may be original, there is very good evidence for the other readings. Usually the more awkward reading is accepted as original, and in this case it may be. But this is such an unusual way for Paul to refer to others it may in fact not be original. Thus, ultimately we are never really sure if it is correct.
The second example comes from 1 Thessalonians 2:7. Here Paul says one of two things. He either says "we became gentle among you" or "we became as children." The problem is created by the fact that in the manuscripts there are no spaces between words. Thus we have two words smashed together and it is not clear where one of the letters should be placed. If it belongs on the end of the first word then the reading is "gentle." If it belongs on the second word then the reading is "children." No one knows for sure. The internal and external evidence gives equal weight to both. The KJV, NAS, NRSV, and CEB all have "gentle." But the NIV has "children." But the NIV has changed. In 1984 it too read "gentle." The fact is, we don't know.
So while it is certainly a problem that we have to deal with variants to the New Testament manuscripts, some are the results of mistakes and others were purposely altered, I think it is misleading to suggest that we can somehow get back to the original. No one has seen them in a very long, long time and we are never sure how close we are. Rather, we have to work with what we have and acknowledge our limitations. So yes, scribal alterations do present a problem for the belief in inerrancy because it ends up making claims about the autographs that we cannot support.