After several master classes at the Ecole Normale de Musique in Paris, given by several of us pianists, a student asked me: “Isn’t it all just a matter of opinion?”
And after so many diverging ideas and approaches, strongly expressed, who could blame anyone for asking that question? With so many differences, perhaps opinions just seem like … random thoughts?
I told him what I believe. “In music — or politics, or anything — the ‘best’ opinions are based on information,” I say.
Example 1:
After Herbert Blomstedt conducted Mozart’s C-Major Symphony, K. 388, I asked him why there’s no minuet in the piece. Mozart scratched it out in his manuscript, Blomstedt says. “Why did he do that,” I persist. “No minuet is necessary or possible,” Blomstedt opines, “it’s Italian opera overture music…”
Example 2:
A prominent pianist is talking about his own changing way of playing Beethoven’s Fourth Concerto — different at each performance, he says. I ask him if Beethoven’s many elaborate annotations in a copy of the piece, documented by Barry Cooper, have any bearing on what he does, in these varying performances of his. 
My colleague falls silent. I speculate on what such early recordings of the concerto as Wilhelm Furtwängler’s with Conrad Hansen, with its considerable tempo modifications within movements, may show us about the flexibility of earlier performance practice in this music? Silence.
We would be terrified of a surgeon who made incisions according to his whims. “Let’s try here…” Should we tolerate that in music?
The surgeon comparison has no value,
it is just game playing. What Beethoven and his audiences heard has no relationship
to what we hear . We have no idea to-day
what they sounded like ,plus the style of
playing, plus instruments (violin all
gut strings ,and the sound that went with
gut strings of the time } We only know the
written word describing what went on for
the ears of that time .A great performance
then ,might not stand up to-day,or
the other way around . It is all a guessing
game ,and the biggest wind bag wins the
day until the next wind bag wins the podium. A 338 is quite different from 444
just for a start .
Well, although many musicians would like to believe otherwise, the stakes aren’t remotely comparable in surgery vs. musical performance. It’s MUCH easier to define success/failure in a surgery; also, “whims” are a virtually essential component of any kind of artistry. For example, I enjoy the whimsy in Art Tatum’s take on a Chopin waltz (via Terry Teachout). “Scholarly” information is just one kind of useful information from which a performer can draw; there’s also lots to be said for intuitive music-making, traditions, whimsy, etc.
I don’t think the concept of opinion really fit this discussion. Very often they are formed by impressions and information that escapes the embedded knowledge of personal critical thinking. Information or knowledge comes later, after a more objective approach of how we think about something, pondering on the very same mechanisms by which we think that we think.
“We have no idea today what they sounded like…”
No idea? Just to take your example of pitch, A can be 338, or 444, ok — but, how about a thousand?
This rings true to me.
As a medical doctor, I believe that even the most experienced specialist never knows exactly how to treat a particular patient. Of course, there’s a lot of information available, but certainty is not part of science. We rely on “experts” because they have a better chance of being right. Their intuitions may be better also, but that’s never all they offer. They combine instinct, information, and conscious thought.
And what’s obvious to the practitioners of one generation may be ridiculous later on.
The surgeon metaphor is not meant literally; its value is to set up a strawman dilemma to put forward an idea.
If one were playing a piece in an early music consortium devoted to historical accuracy, the sudden appearance of a saxophone where the krumhorn should be would produce a puzzling
“wrong incision”.
The fact that one contestant in the Van Cliburn competition plays Mozart like Mozart, and another plays Mozart like Rachmaninoff may also be botched surgery of a sort, but much less troubling.
In the more nuanced dilemmae of the post,
the choices are more akin to millimetric differences in scalpel width–of fascination to the practitioner, but perhaps of less cutting interest to the patient listener.