How do the travails of keyboard temperament apply to instruments without fixed tuning, like violins, trombones, flugelhorns, and the human voice? They don't apply at all. Most of the time violinists, et al., tune by ear, on the fly, note by note, and chord by chord. That's why a string quartet or an a cappella choir can be better in tune with nature than a guitar or a piano can. As a high-school trombonist playing with a piano for the first time, I found adjusting to keyboard tuning a pain in the neck—without knowing why. String recitalists know that pain intimately. Meanwhile, an orchestra is made of a bunch of instruments, some of which tune naturally by ear—strings, woodwinds, brass—but also instruments in fixed, equal temperament: harp, marimbas and xylophones, harpsichord and piano, etc. What do orchestras do to harmonize all those conflicting demands? They do the best they can and try not to think about it too much. It can make you crazy.
I think professor Duffin is entirely rational in advocating period tunings when possible to play repertoire written for those tunings—for the same reason that it's good to hear period instruments sometimes, for pleasure and edification. Yet to date there are few recordings in period tunings. Even most recordings from the Historically Informed Performance, aka HIP, movement use equal temperament. I'd go so far as to suggest that performances on period instruments in modern tuning are half-assed, or half-HIPped, if you like. As tuning activist Kyle Gann says on his Web site, "Playing Bach's Well-Tempered Clavier in today's equal temperament is like exhibiting Rembrandt paintings with wax paper taped over them." Still, nobody can reasonably claim that piano works after the early 19th century should be played in other than the equal temperament they were written in. Says my Boston Conservatory colleague Jim Dalton, himself more equal-tempered than many aficionados, "Equal temperament is the price we pay for all the marvelous modulations and exotic scales" from Schumann through Debussy to the present.
Ah, but the metaphysical laughter is still there, even between these very lines you are reading. One of the few pianists who have recorded in period tunings (on a modern Steinway) is Enid Katahn. Let's compare two clips. First, here's the finale of Beethoven's Pathètique in equal temperament, by Andras Schiff:
Now here's Katahn on the same, in an early-19th-century tuning called Prinz, from her recording Beethoven in the Temperaments:
Now an existential question: People have been at the point of murder over those two tunings, but can you tell the difference? Can you really? Some of you can, certainly. Some of you who think you can are fooling yourselves. And most of you can't tell the difference. Here are two short clips from the above, juxtaposed, first Schiff then Katahn. Maybe this way you'll get a whiff of what the fuss is about.
In any case, we're stuck in the Twilight Zone. The anomalies of tuning are the musical equivalent of the uncertainty principle in physics, which says that you can tell where an electron is located or how fast it's moving, but not both at the same time. Another example of the gods' sense of humor. For me, it's all a clue to the nature of the gods, which Pythagoras and the Greeks understood supremely well: The masters of the universe don't make much more sense than we do, but they are all-powerful and they sure love to play with our heads.
And so, professor Duffin, ladies and gentlemen, and the gods: From Greeks to geeks, do I care about all this meshugas? In some respects, I don't want to think about it. If I start obsessing over the fat major thirds in equal temperament, they might drive me crazy, too. As if I, and all musicians, don't have enough trouble already. Nonetheless, I yearn to hear Beethoven's A flat major and E flat minor on a period piano, in a tuning he knew. And Bach's WTC sounds weller in real well-temperament. I wish HIPsters out there would get busy and fix their period instruments in tunings Bach wouldn't scoff at.