One of the most lauded living composers, Thomas Adès has not written extensively in full symphonic dimensions. PHOTOGRAPH BY EAMONN MCCABE/REDFERNS/GETTY

Last month, the online radio station Q2, a new-music adjunct of the New York classical station WQXR, hosted a twenty-four-hour marathon of contemporary orchestral music, entitled Symphomania. The project originated in a passing Twitter comment by the critic and musicologist William Robin, who, back in December, made the boldly arguable claim that “Play,” a kaleidoscopically churning forty-five-minute score by the young Los Angeles-based composer Andrew Norman, “might be the best orchestral work that the twenty-first century has seen thus far.” Robin’s comment set off a lively discussion on Twitter, with composers, critics, and connoisseurs nominating dozens of other pieces for the honor. Robin compiled the results in Storify format, at which point Q2 approached him with the idea of curating a radio festival. So it goes in the fast-and-furious world of classical-music social media, where a single Tweet can unleash hours of audio from the Donaueschingen Festival.

Robin’s enterprise affirmed the vitality and variety of recent orchestral writing: the music on offer ranged from euphonious effusions in a post-minimalist vein to dissonant fulminations of the avant-garde. At the same time, it implied a critique: audiences have relatively few opportunities to hear big-boned works of this kind. Composers can easily obtain commissions for pieces of the overture or tone-poem type, lasting from seven or eight minutes to eighteen or twenty: these are of the right size to be wedged between a concerto and a symphony. It is far more difficult to take control of an entire half of a program—to assume what might be called the Tchaikovsky position. (Never mind Bruckner and Mahler, who often have entire concerts to themselves.) The assumption is that audiences might be able to fidget through a quarter hour of modern music but couldn’t stomach a half hour or more of it. If you schedule something like Norman’s “Play,” you are handing over the reins to a living composer—in the eyes of many administrators, a move akin to giving a jumpy teen-ager the keys to the family car.

Furthermore, the writing of symphonies in the conventional sense has, in the past century, fallen out of fashion in many musical circles. Debussy, Ravel, Bartók, Janáček, Schoenberg, and the majority of postwar composers never produced a full-scale Beethovenian symphony. Still, the urge to paint on a large orchestral canvas remains strong. In works as various as Norman’s “Play,” John Luther Adams’s “Become Ocean,” and Chaya Czernowin’s “MAIM”—all on the Symphomania playlist—you become lost in an intricately constructed and finely variegated world, as you do in a major novel or film. I was especially gripped by Georges Lentz’s “Jerusalem (After Blake),” which had its première in Luxembourg, in January. It is a controlled pandemonium that includes a wild, lashing part for electric guitar and a spatially distinct brass ensemble that, in the final bars, is directed to play a tinny recording of itself, via smartphones. I’m longing to hear the piece live, alongside other recent Lentz scores: “Jerusalem” is a component of a multi-part cycle called “Mysterium,” which would require the better part of a day to perform.

As it happens, the New York Philharmonic held its own version of Symphomania in March, presenting two contemporary scores that broke the half-hour barrier and commandeered the second half of a program: Thomas Adès’s “Totentanz,” a song cycle for mezzo-soprano, baritone, and orchestra; and Adams’s “Scheherazade.2,” which is described as a “dramatic symphony for violin and orchestra.” Adès and Adams are two of the most lauded living composers, yet neither has written prolifically in full symphonic dimensions. “Totentanz” is Adès’s most capacious non-operatic effort to date, and “Scheherazade.2” joins two prior large-scale Adams pieces, “Harmonielehre” (1984-85) and “Naïve and Sentimental Music” (1997-98).

I wrote about “Totentanz” in advance of the Philharmonic performance; hearing it live, I registered even more strongly Adès’s command of instrumental theatre. The Adams, which was receiving its world première, I heard in an open rehearsal—less than ideal conditions, with Alan Gilbert interrupting frequently to confer with the composer, the musicians, and the soloist, Leila Josefowicz. All the same, the outlines of this latest Adams creation emerged. It speaks much the same language as “The Gospel According to the Other Mary,” the composer’s most imposing work of recent years: the Romantic minimalism of past decades has given way to a kind of Romantic neo-modernism, with episodes of dissonant density abutting lush, Sibelius-inflected textures. In his latest phase, Adams leans on unison lines that go crawling through various sections of the orchestra, defining harmony horizontally rather than vertically. The form is restless, unpredictable, yet ultimately confident in its progress. Adams attached a feminist program, highlighting the misogyny of the Scheherazade legend; the protagonist holds her own against dogmatic thrashings of the orchestra, and steals away in a mood of melancholy rapture.

The double whammy of Adès and Adams at the Philharmonic—noted also by my colleague Allan Kozinn, in a Wall Street Journal review—makes one wonder about the future course of the orchestra, which will part ways with Gilbert in 2017. While Gilbert stated that he wished to stay no longer than that, his departure seems premature. Not since the heady period of Bernstein and Boulez, in the sixties and seventies, has the ensemble shown such a sense of intellectual direction. Gilbert has received praise more for his interpretations of twentieth- and twenty-first-century pieces than for his accounts of the core repertory, but the latter are never less than solid, and certain of his festival-style presentations, such as Ligeti’s “Le Grand Macabre” and Stockhausen’s “Gruppen,” at the Armory, have been transfixing. What next? The Philharmonic is now said to be giving serious consideration to Esa-Pekka Salonen, who led the L. A. Phil to glory in the nineties. Salonen’s regime has been an obvious model for Gilbert’s at the Phil; as Kozinn points out, this raises the question of whether Salonen would want to repeat the experiment on a different coast, under possibly less sympathetic conditions.

Anthony Tommasini, at the New York Times, recently responded to a reader who complained that critics are applying the wrong criteria in evaluating potential successors to Gilbert—that they praise new-music specialists while the audience prefers masters of the tried and true. “The garbage Mr. Tommasini is talking about will be forgotten in ten years,” wrote Richard77, of Nyack, New York. “Why should we have to put up with it in the meantime?” The “garbage” category seems to include, alas, Debussy, Bartók, and Stravinsky. If I were a young composer reading this, I might contemplate an alternative career in robotics. If Debussy, a man born in 1862, is too radical for the average Philharmonic subscriber, what hope is there for those in their twenties and thirties?

It has been said before, but it bears repeating: the beloved classics would never have existed if audiences of the past had taken such a dim view of the new. Transport Richard77 back in time, and he would be the sworn enemy of all that he claims to cherish. Can tradition-minded classical listeners ever be made to grasp the crippling contradictions inherent in their hostility toward contemporary music? The question hangs in the air, because the future of the art depends on it.