A couple weeks ago, I finished Bart Ehrman's bestselling Misquoting Jesus: The Story Behind Who Changed the Bible and Why. I'm not going to do a full review of the book at this point, but I wanted to record some thoughts on what I see as Ehrman's master argument.
The bulk of the book is just standard textual criticism. Ehrman tends to be more radical on a few points than the average textual critics, but most of the book simply presents consensus views on the history of the discipline and gives examples that mainly do illustrate the points he wants to make. He's often criticized for the suggestion that the examples he picks are only the most extreme and thus give the impression that the textual changes are more common and more extreme than they really are. He responds that he does say that most changes are extremely minor and that the cases he's presenting are unusual. But what his response ignores is that his own master argument makes an explicit case for the point that his critics are only accusing him of suggesting, and he takes offense even at that accusation.
His master argument is presented in the introductory chapter and then again in his conclusion. The argument is basically as follows:
1. We know that there are textual changes in manuscript transmission.
2. Some of these are ideologically-motivated.
3. The earlier manuscripts have more diversity due to less-careful copying practices.
4. It's possible that there were changes in ideology from the original manuscripts that we no longer thus have any evidence of.
5. Therefore, we can't have much confidence about what the original New Testament manuscripts said. All we can do is give arguments for which of several existing readings were the earliest.
I think he overstates the ideological changes, although there indisputably are some. I didn't find myself agreeing with all his cases, several of which were extremely controversial among scholars (e.g. I Cor 14:34-35, which a few but only very few notable scholars think is an addition to the original text). I think the fact that there are more readings in earlier manuscripts makes it more likely that the original reading is among the surviving manuscripts in any given case, even if it also raises the possibility that we can't know if the original survives. So that same fact provides some support for opposite views.
But the main issue is really epistemological. Ehrman holds to a skeptical standard when it comes to being sure of original manuscript readings that would lead to hopeless conclusions about ordinary knowledge. Hardly anyone in epistemology accepts this kind of standard anymore, even if it has had firm support in the history of philosophy (perhaps most famously with Rene Descartes). The chance that any particular well-attested reading among the NT manuscripts is really the product of an ideological change from the original manuscript is extremely low.