Our ephemeral canon

One of the best-kept professional secrets among classical musicians is the wild state of affairs that persists in sheet music for even the most standard repertoire.  While meticulously researched editions of scores are readily available and new editions, based on alternative souces and editing principles, appear with some regularity, very often the sets of parts that an orchestra will have on their stands — whether an orchestra owns or borrows a set and which particular set they own or borrow often depends upon some delicate practical and financial considerations —  belong to older editions, at variance with the chosen score, and many sets of parts can only be brought into reasonable concordance with the conductor's preferred score through considerable amendation by the conductor, orchestral librarian and/or section leaders.  For this reason, orchestras with their own libraries work hard to conserve such edited sets and many of the best conductors make a point of owning their own sets of parts, hand-edited to their satisfaction. While, on the one hand, this makes for a certain amount of lively variety in at least the details of the repertoire, on the other hand, this leads to some fairly substantial existential uncertainties about much of the music.  I've heard, for example, that the set of parts of the Mahler First most often owned by orchestras — which is a cheap reprint of an edition with a lapsed copyright — has on the order of eight to nine hundred non-controversial errors which have to be corrected by hand before one has a set of parts that can reasonably be expected to function together.  While Mahler, who was liberal in the extreme with the quantity of his marking, may be an extreme case, the indeterminancy here should at least give some philosophical pause when one wants to point at The Mahler First, because, amid the variations in Mahler's own manuscripts and parts, amid the various scores and sets of parts, and then amid all of the interpretive and accidental variations that enter into real performances, there is scarcely anything to hold on to.  All that is solid melts into air, and all that...