Part 1 is available here.
TWH: Let me give you a couple of reasons for why I believe that we do not have an original manuscript (fragment or otherwise) of a New Testament writing. First, most scholars, if not all, do not think any of the earliest extant New Testament manuscripts are original. Let me just point out what a few have said. Philip Wesley Comfort writes:
"Unfortunately, not one autograph of one NT book is extant. The closest copy we have to an autograph is a papyrus fragment (P52) dated c. 100-115, containing a few verses of John 18 (31-34, 37-38). This scrap, only twenty to thirty years removed from the autograph, is a fragment of one of te first copies of John's Gospel." (Early Manuscripts and Modern Translations of the New Testament, 4)Lion Vaganay and Christian-Bernard Amphoux write, "Of the autographs of the New Testament, nothing is known precisely, other than that, if they existed, they soon disappeared" (An Introduction to New Testament Textual Criticism, 90). Saying "if they existed" seems like a strange thing to say because it is. Of course, they existed. But the point worth noting here is the consensus they disappeared, and, according to these authors, they did so quickly. They add, "It is not really surprising that the New Testament manuscripts should have been lost so quickly. In all probability, they were written on the usual material of the time, namely fragile papyrus" (90). That material, they say, "would not have been tough enough to stand up to much handling" (90). Now I've been known to go against the status quo and sometimes I row my boat in the opposite direction than that of the scholarly world (e.g., Matthean priority, textual criticism, etc.), so I don't want you all to think that this is the end all be all evidence for me. It's not. But it is something to consider every time we think about an issue. "What do the 'experts' say, and do they have a good reason for saying so?" In this case, I think they probably have a pretty good reason for thinking that we do not have an original manuscript. That leads me to my next point.
Second, the authors of the New Testament wrote what they wrote not so that it could sit in an world-renowned library or archive, but for use in ministry. Let me explain a little. The Gospel according to Matthew was written as a discipleship tool (think μαθητεύσατε πάντα τὰ ἔθνη in Matt. 28:19-20). Paul would have even carried a copy of Matthew with him on his own missionary travels. This Gospel was copied, carried, held, read, and studied. Such use would have worn out the original. Paul possibly kept his own letters, sending duplicates (which would also be considered originals) to his audiences whenever he sent a letter. Those letters were immediately copied, reproduced, and distributed. Sometimes Paul even makes that clear in the letter (e.g., Colossians and the lost letter to the Laodiceans [Col. 4:16]). Other New Testament letters, such as Galatians and 1 Peter, were written to larger geographical areas. The only way those letters get to the their intended audiences is not by way of a caravan touring the countryside and making stops along the way, but by a concerted effort to copy and distribute. When we think about that, it makes it unlikely that the originals would not have suffered from expected wear and tear, eventually bringing the manuscript to a state where it was no longer usable. That wasn't a big issue back then. The early Christian community wasn't committed to saving artifacts or relics so that it could fill libraries or cathedrals. They were committed to preserving and distributing the actual content of those letters.
Our modern editions of the Greek New Testament are reliable and trustworthy. But that doesn't mean that there is no need for study. Just as translations are reliable and trustworthy vessels that carry the message of the New Testament from Greek to, let's say, English, modern Greek editions are reliable and trustworthy vessels that carry the words of the New Testament from manuscripts, with their variations, to a single text that can be read and studied in one volume. Modern Greek editions generally have what we call an "apparatus" at the bottom of the page that gives us a selection of manuscript witnesses that support different readings. While it's true that those lists are hardly exhaustive, they hit the major textual variants that have significant impact for how we interpret what the New Testament says.