Reply #25: There are a number of heuristics to help navigate the

[Igel]

sea of ambiguity and uncertainty that medievalists run into.

This is certainly one of them: Few are going to say things that would seem to thwart their purpose.

Textual critics have a sort of parallel hypothesis: In the choice of two alternative readings (say, in different mss. of a single text), choose the harder readings. People will "correct" texts to what they think make more sense; they're unlikely to "correct" it to what they'd think is gibberish. Errors creep in, to be sure; but a fair number of "difficult" readings have turned out to be good. Words that weren't attested elsewhere, screwball grammatical constructions, or sentences that really do mean what people found it difficult to believe they meant.

Both the "embarrassment" and the "harder reading" business also work in fields *other* than NT studies.

Note that these don't provide the upper limits on what you know, however. Having shown that a text reliably reports a number of embarrassing facts makes it more likely that it also reliably reports facts that are also self-serving, or at least that those bits weren't added later. Same for difficult readings: If you get difficult readings in a text, it's more likely to be old and not a forgery (with some notable exceptions: The "Lay of Igor's Host", an apparently Old Russian text, is almost certainly a forgery, one composed by a scholar who knew enough to introduce difficult readings not so much in the interests of textual misdirection, but for "flavor"--all authentic texts had screwy passages, so his fake text had to have screwy, authentically scewy, passages).

As for proving Jesus' existence ... there's not really much proof. He didn't merit much documentation, it seems.