There was a time when it was quite acceptable in scholarly circles to resolve Talmudic cruxes by positing an abbreviation that was incorrectly interpreted. In other words, when faced with a word (or phrase) that was difficult to interpret in context, the explanation would be given that originally a different phrase had appeared, bearing the same initial letters. A scribe shortened the phrase to those letters, and a later scribe misunderstood them and wrote some new words that have no meaning.
This line of interpretation was championed by Louis Ginzburg, who wrote an article in Students' Annual, a JTS publication from long ago, entirely devoted to using this method to explain obscure passages in the Jerusalem Talmud. Victor Aptowitzer did the same, for other Talmudic sources. Today I came across the method in a comment by Shmuel Kalman Mirsky, in his edition of the Sheiltot.
The only example that comes to mind, though, which I haven't gone back to check (I know that Ravitsky wrote an article on the topic, in his book Al Da'at HaMakom) is Rashi's comment on Deuteronomy 11:18. There he says:
Even after you go into exile, distinguish yourselves with commandments. PutThis is surprising, since one would have thought that these mitzvot are precisely the kind whose observance is unrelated to geographic issues. Therefore, someone said (and I have no idea where I heard this) that the original text (or, at least, a more original version than the printed edition) had the abbreviation tu"m. This stood for terumot uma'asrot, agricultural laws that are indeed applicable in the land of Israel. A copyist misconstrued the abbreviation, and the above text was created.
on tefillin, make mezuzot, so that they not be new to
you when you return.
But we know that the performance of mitzvot including tefillin and mezuzah was indeed lax for much of Jewish history (as Kanarfogel has shown). And it is difficult for me to imagine how such an error could have actually developed.
In general, I think this method has fallen out of favour. That was my thought. As an aside, I suspect that Saul Lieberman didn't like this method too much himself. In his methodological introduction to Talmudic philology, Al ha-Yerushalmi, he mentioned Ginzburg's article, but he quotes only two of them, without much enthusiasm. But maybe I was reading that into him.
My other thought has to do with enthusiasm about manuscripts and their significance for scholarship. I hope my passion for manuscripts is not in question. But their contribution to the elucidation of the text is often overrated. My theory is that the more exposure a scholar has to manuscripts, especially texts outside his specialized focus, the more sober he is in appraising them.
A few stories may illustrate this. One is my last conversation with the late Prof. Ta Shema. As he was walking me out of his study, he spoke heavily about the IMHM as "riches kept by the owner to his detriment." It was clear that decades of working with manuscripts, poring over thousands of microfilms, had left him overwhelmed and exhausted.
Another story. A Talmud class at Hebrew University. The professor points out difficulties in a chapter of mishnah. One of the students, a pensioner with great enthusiasm for his studies, suggests brightly "Well then look in the manuscript!" And the teacher explains patiently that he had already looked in the manuscript, and his problem remained.
Reading through different manuscripts, one becomes inured to minor stylistic shifts, additions or elisions, different forms of a single word. Not every variation is worth getting excited about. In fact, most variations are almost meaningless. And even if a particular variation seems to be exciting, chances are it isn't.