In his books, Horowitz posits that the late 19th century was the apex of American classical music, before it degenerated into a “culture of performance,“ spotlighting celebrity conductors and instrumentalists, whom he terms “performance specialists” in contradistinction to the composer/performers of an earlier era. He is credited (as by Alex Ross of The New Yorker) with coining the phrase “post-classical music” to describe an emerging 21st-century musical landscape merging classical music with popular and non-Western genres.[2]
Horowitz’s treatment of late Gilded Age culture challenges prevalent notions of “social control” and “sacralization” as defined by such cultural historians as Alan Trachtenberg and Lawrence Levine. In Wagner Nights: An American History and Classical Music in America: A History of Its Rise and Fall, he argues that American classical music of the late nineteenth century cannot be viewed as an instrument of affluent elites. In Understanding Toscanini: How He Became an American Culture-God and Helped Create a New Audience for Old Music, he treats the “Toscanini cult” of the mid-twentieth century as a metaphor for the decline of classical music in the United States, arguing that the conductor Arturo Toscanini became the first non-composer to be widely regarded the “world’s greatest musician“, and that no prior conductor of comparable eminence and influence had been so divorced from the music of his own time. Wagner Nights also proposes that American Wagnerism of the 1880s and 1890s was (compared to European and Russian Wagner movements) distinctly meliorist and “proto-feminist“, the vast majority of American Wagnerites having been women.[citation needed]
In 2002, Horowitz co-created PostClassical Ensemble (PCE), a chamber orchestra in Washington, D.C., for which he served as executive director, then executive producer through 2022. For Naxos, he produced nine PCE CDs and four DVDs featuring little-known American works.[5] He also directed Music Unwound (restarted later as Music Unwrapped), a national consortium of orchestras and universities originally funded by the National Endowment for the Humanities.[6] During the COVID-19 pandemic, he wrote and produced a series of six Naxos documentary films called “Dvorak’s Prophecy”.[7] This led to his “More than Music” series for NPR, broadcast via 1A. He has released two more books,The Marriage: The Mahlers in New York (his first novel) and The Propaganda of Freedom: JFK, Shostakovich, Stravinsky and the Cultural Cold War. He is also active as a vocal accompanist.
As a concert producer, Horowitz was an artistic advisor to the Schubertiade at New York’s 92nd Street Y, for which he created all-day Schubert symposium incorporating film, Lieder, and chamber music (1981–1994). During his tenure with the Brooklyn Philharmonic, the orchestra received the 1996 Morton Gould Award for Innovative Programming from the American Symphony Orchestra League (ASOL), as well as five ASCAP/ASOL awards for Adventuresome Programming. According to Alex Ross in The New Yorker (November 1997), “When Joseph Horowitz became executive director, the Brooklyn Philharmonic more or less went off the grid of American orchestral culture. The subscription-series template – overture, concerto, symphony – has been thrown away. Programs have become miniature weekend festivals.”[9]
Beginning in 1999, Horowitz has served as a freelance artistic consultant; he has conceived more than five dozen thematic interdisciplinary music festivals for a variety of orchestras and performing arts institutions. Funded by the National Endowment of the Humanities, he created "Music Unwound," which produced festivals linking orchestras with educational institutions.
