It is not the piano, it is recording and computer technology that has created the bridges between different parts of the American musical space. In our postmodern age, with world music increasingly represented, even in classical concerts, there is no longer a need to find an American sound to put beside the European styles of the past. It is, anyway, of dubious service to composers, who naturally dislike being pigeonholed. And if there is no stylistically cohesive, commonly performed canon of American classics, that state of affairs has its good and bad sides. Where would iconoclasm get you if you were going to be judged against revered, canonical works?

In introducing the African-American segment of the concert program, Horowitz quotes Dvorák's well-known observation, made during a visit to the United States in the early 1890s, on the present and future state of American "serious" music: "I am now satisfied the future music of this country must be based upon what are called the Negro melodies," he told a reporter.

Whatever shock and derision Dvorák's comment occasioned at the time, it seems oracular today. Or perhaps semioracular, for Dvorák could not have known how much recording, then in its infancy, would change the rules of music composition. In his world, folk music composers were unknowns whose music was appropriated by literate composers, and incorporated into their literate compositions. Dvorák probably expected "Negro melodies" to be treated in the same way.

But what African-American composers provided were finished compositions and a clearly demarcated style of playing and imagining music. So classical compositions utilizing jazz began to seem like unsatisfactory hybrids. That's why European literate composers' infatuation with jazz peaked in the 1920s and declined thereafter. That's why Copland ended his flirtation with jazz. That's why Gershwin, the classical wannabe, was so successful with his hybrids — he came at composition from a mixed, populist standpoint from the beginning. He didn't have to change his style to write Rhapsody in Blue — it's a bunch of his (fabulous) 32-bar song forms strung together.

Even more important, the advent of commercial recording changed the relationship of literate and nonliterate musicians. In an earlier century, blues guitarist Robert Johnson, folksinger Huddy ("Leadbelly") Ledbetter, and numerous other nonliterate musicians would never have been preserved as recognizable personalities. But they are for us. Also, jazz musicians never have had to moderate the improvisatory wellsprings of their art in order to have their pieces "classicized." A work becomes fixed through the composer's (or another jazz artist's) recording of it.

Young jazz musicians have always studied their music history by learning and memorizing famous recordings. This was demonstrated from the stage on Saturday night, when pianist Steven Mayer played Ferdinand "Jelly Roll" Morton's Frances. Mayer had learned the piece from a transcription. But that last stage — writing it down — is rendered less necessary with every jump in technology.

So the tremendous impact that the African-American tradition was already having on American music was broadened by recordings and turned into an art music before it could be appropriated, and what took place instead was a dialogue that overrode the racial segregation of the time. Many jazz composers (like Fats Waller, Sidney Bechet, Art Tatum, and Billy Strayhorn) were classically trained, and all absorbed some European influences in their youth. That's how, for example, the harmonies of Debussy worked their way into jazz.

And this cross-fertilization moved rag and jazz composers to try their hands at larger-scale compositions, something that resulted not just in Gershwin's great works, but also in Ellington's suites, such as Black, Brown, and Beige, which is symphonic in scale and ambition. Had racial politics not largely barred African-Americans from access to symphony orchestras and opera houses, who knows how many Rhapsody in Blues, how many Porgy and Besses would be out there? Who knows what James P. Johnson, whose symphonic works are mostly unfinished torsos, would have accomplished?

These thoughts occurred to me as I pondered the concert program and listened to its first half. But over and over again, I was struck by the ways in which the polemical and pedagogical aspects of the concert seemed to go off the rails.

The polemical message seems directed at classical institutions: Do more programming like this. Horowitz's prod comes a little late, though. In his lecture, he mentioned that recent performances of Gershwin's An American in Paris and Rhapsody in Blue at the Boston Symphony Orchestra (the latter in 2005) were the first time that those pieces had been featured on a regular subscription concert in Boston, other than on pops programs. Should we infer from this, as Horowitz seems to expect, that Gershwin has only recently been accepted as a classical concert-hall staple?

Why, then, has a full symphonic orchestration of Rhapsody existed for so long? Bernstein's famous performance and recording of it (released in 1959), which has now sold in the umpteen-millions, has been followed by many others, from André Previn to Michael Tilson Thomas, solid classical musicians all. Most recently, locally, the Oakland East Bay Symphony performed it under Michael Morgan (see review), and the Santa Rosa Symphony performed American in Paris on a program with Tan Dun's Crouching Tiger Concerto, Bright Sheng's Tibetan Swing, and Bernstein's Symphonic Dances from West Side Story. This last is a program that makes the point about diversity as creatively and unconventionally as "The American Piano" tour.

In fact, film music and film-derived music, like Tan Dun's Concerto, are far newer imports to classical concert programming. Even in symphony orchestras, the barriers between classical and other types of music are fast disappearing. Multiculturalism began as an accident: Recording technology paved the way for marginalized musicians to be heard and recognized. But with postcolonial literature, the cross-cultural experiments of the 1960s, and other stimuli, multiculturalism has taken on a life of its own in classical music, expanding our horizons far beyond the bounds of America itself. You hear it in the programs of the Kronos Quartet. You hear it in composer Osvaldo Golijov, a U.S. resident since 1986, who merges klezmer, tango, and European classical music. You hear it in Yo-Yo Ma's Silk Road Ensemble, which has collaborated with Golijov and a huge variety of other musicians. Accept Gershwin? We're way past that. In the new century, a swelling chorus of voices is un-defining the boundaries of what sounds American.

The classicizing of the elder jazz tradition proceeds apace. New works based on "Negro melodies" (like Olly Wilson's Hold On, another in the line of great American symphonies, performed last month by the Berkeley Symphony — see review) continue to be written. And the concert hall is beginning to reflect the exuberant explosion of research into American music of all kinds. None of this suggests "the neglect of native repertoire" of which Horowitz complains at the beginning of his program notes.

In the new century, where we agree that diversity is the "defining attribute" of American music, we have to be wary of old binary oppositions rearing their hoary heads. Here's Horowitz on Art Tatum's scintillating Humoresque: "Try to imagine Tatum's Humoresque played by an orchestra. It is in fact unimaginable. Orchestras cannot improvise. Their cushioned sonorities are, in tendency, European: decorous, refined. The spontaneous ingenuity and daring impulsiveness of Tatum's art — its very essence — demand the piano."

Hmmm. Europe, super-refined. America, raw and edgy. American music spontaneous; European music rigidly predetermined. Is this a tad oversimplified, perhaps? Outside of a nationalist, patriotic context, do we need such distinctions? What happens if an American composer doesn't write music that sounds raw, edgy, and spontaneous? Is he drummed out of the club?

In another unworkable dichotomy, Horowitz explains the prevalence of the piano in American music, the main idea, he said, of "The American Piano." "One reason the piano is such a protean medium for the American experience is that, unlike the symphony orchestra, the opera house, or the string quartet, it is not weighted toward Europe. Rather, it is a neutral and democratic instrument, as amenable to Joplin as to Beethoven, as comfortable in the nightclub as the concert hall."

But lots of instruments are comfortable in a variety of contexts, like the trumpet, the fiddle — oops, the violin — and the clarinet. The real reason for the dominance of the piano, and other keyboard instruments throughout history, is more disappointingly mechanical: The piano does polyphony with only one performer. That's what makes it the ideal medium for lots of "maverick" musicians and outsiders, not just Americans. Erik Satie, anyone? And, of course, the piano's prevalence in American art music does have something to do with the country's connection to Europe. We wouldn't ever have had this tussle with European influence if we didn't feel we had to escape from it.

And there are political issues at work, as well. When, in the new century, we use the term American, or Americans, we ought to recognize that most of the time we're actually limiting the group to less than the totality of all Americans. In the new century, at a time when many people around the world and in the United States have real concerns about the hegemony of American power and culture, perhaps we should drop our old insecurities about the dominance of the European art music tradition, and do some serious listening. We're all citizens of the world. Global warming doesn't know cultural boundaries. The energies that we used to put into national self-identification and patriotic posturing would be better used to foster international cooperation. There's a big role for all music in such a project.