One of my current interests lies in an attempt to answer the question of why some ancient scribes felt free to make intentional changes to the NT traditions as they copied them, while other scribes conducted their work more conservatively and tried, to the best of their ability, to reproduce their exemplars perfectly. Answers have been offered for particular kinds of scribal editing (e.g. Ehrman’s Orthodox Corruption of Scripture), but I am wondering why, given the apparent fixity of text, such habits even existed in the first place. Leaving small editorial changes, like alterations to spelling, to one side, let’s think about a few examples of scribal changes—two of which are quite major and have become much-beloved by many Christian readers.
Mark’s Ending, Bezae’s Luke, and the Pericope Adulterae
Off the top of my head, I can think of three examples of the NT gospels growing through the additions of later scribes: the endings of Mark 16, Luke 6 in Codex Bezae, and the Pericope Adulterae in John 8:1-11. Of course, I am tipping my hand to some of my assumptions on these debated texts: I think Mark ends at 16:8, Bezae’s addition to Luke 6 (otherwise unattested) is not original, and that the story of the woman caught in adultery in John 8 is a much later addition to John’s text. But these contested texts are just some particularly good examples of the phenomenon I’m talking about; the so-called “free text” manuscripts of the gospels (e.g. P45) are more ho-hum examples of scribal freedom to alter the traditions being copied.
Mixed-Media Culture, Chirography, and Textual Threat
It’s interesting to me that the technology of chirography (handwriting) gave rise to a heightened system for fixing and securing traditions, even while some scribes persisted in editorial freedom. I wonder if it doesn’t have something to do with the mixed media culture of antiquity. Early Kelber wasn’t so off-base; there is something to the shift in medium from oral to written that affects the shape of the tradition. Writing allows for some movement towards stability, if for no other reason than written documents are very concrete aids to memory. You don’t have to recall the tradition from memory; you can look at it. It’s right in front of you.
But still, some scribes persisted in making their changes; some of them smallish and relatively unobtrusive, others striking and and obvious. Is the freedom to alter a ‘hangover’ from a predominately oral media culture in which small changes were allowed, so long as the tradition remained largely intact? Might some scribes have been operating akin to oral performers, whose task was to retain the gist of the tradition, in the reproduction of their texts?
Chirography also affords authors some ability to secure the tradition by textual threat. Revelation 22:18-19 famously threatens any scribe who would add to or take away from the text with divine plagues and denial of the benefits of the tree of life. Such a textual showing of force is not unique. As R.H. Charles points out in his classic commentary on Revelation, there are more than a few examples of ancient authors of written texts proscribing the alteration of their text: Deut 4.2; 1 Enoch 104.10-11; Letter of Aristeas 310-311; 2 Enoch 48.7-8; Josephus, Contra Apion 1.8; Irenaeus in Eusebius HE 5.20.2; Rabbi Meir in Sota 20.
As the reasoning goes for laws, I suppose you don’t threaten against what isn’t already happening. Are these textual threats evidence that relative levels of freedom in scribal activity were common in antiquity?
What are the Rules? Why Changes?
I’ll end with some questions, and would welcome your responses: Was there a sense that some texts, but not others, could be changed? Was there some kind of media-cultural rule set governing which was which? Or do the above examples give us the “default setting” for expectations of scribal activity? If so, why so many examples of intentional scribal changes?
 R.H. Charles, A Critical and Exegetical Commentary on the Revelation of St. John, vol. 1, 2 vols. (New York: Scribner, 1920), 223–4.