The social world of opera-going may be headed the way of polar bears and ice caps, but society hasn’t disappeared. A hierarchical social world has managed to absorb the omnipresence of music pretty effortlessly. You can see this in the violent intragenre squabbling that animates indie rock circles, and in the savage takedowns of avant-garde opera performances in art-music magazines. Meanwhile the proliferation of genre names represents an ever finer process of social differentiation, each genre’s acolytes determining (as Serge Gainsbourg put it) qui est “in,” qui est “out.” The rise of generic distinctions has lately reached a climax of absurdity, such that we can name off the top of our heads: house, witch house, dub, dubstep, hardstep, dancehall, dance-floor, punk, post-punk, noise, “Noise,” new wave, nu wave, No Wave, emo, post-emo, hip-hop, conscious hip-hop, alternative hip- hop, jazz hip-hop, hardcore hip-hop, nerd-core hip-hop, Christian hip-hop, crunk, crunkcore, metal, doom metal, black metal, speed metal, thrash metal, death metal, Christian death metal, and, of course, shoe-gazing, among others. (Meanwhile, 1,000 years of European art music is filed under “classical.”) Some people listen to some of these; others, to only one; and others still, to nearly all. And this accomplishes a lot of handy social sorting, especially among the young, whenever music is talked about or played so that more than one person can hear it.