A John Lennon song floated over our rental-car radio as my father and I wound our way past silos and dairy farms in the Upper Peninsula of Michigan. Lennon’s voice made me nostalgic for the late 1960s, which was odd, because it was the late 1980s and I was a teenager who had only known pop charts ruled by the likes of Rick Astley, Tiffany, and Belinda Carlisle. “Why doesn’t my generation have any real artists like Lennon?” I asked bitterly.

My dad shot back that he never understood why The Beatles were considered great artists. “You’re always listening to lyrics,” he said, slipping the knife in. “What made John Lennon so important?”

What a stunningly stupid and provocative question, I thought.

My father should have known better. He had protested the 1968 Chicago Democratic Convention and had written a dissertation on how children are politicized. The really irritating part, though, was that I knew saying, “Because John Lennon was John Fucking Lennon,” was no kind of answer. And if I couldn’t explain why John Lennon mattered, how could I justify my obsession with R.E.M., Talking Heads, and the Clash? Or why I, a white kid from California, knew most of the rhymes from N.W.A.’s Straight Outta Compton, and could (and did) rap the profane lyrics of “8 Ball” while waiting for my 99-cent Whopper at the Burger King drive-through? The music was mind invasion. A pop song could take me into a world I had never seen, a separate sensibility, and four minutes later I would emerge changed. Of course, I didn’t quite have that formulation at my fingertips. So I accused my father of trying to suck the pleasure from what mattered to me.

The reason Lennon mattered, and the reason I still listen to music that often amounts to bad teen poetry and dance beats, has to do with the quality that unifies the ever more fractious pop-music universe and distinguishes it from classical and jazz: anyone can make it. Pop music is not unprofessional. It is anti-professional. This is not to suggest that the pop canon is devoid of trained musicians, composers, and producers, or that all pop music is artistically equal. Rather, it is to say that the notion that anyone can write a pop song—be they hip-hoppers or cowboys, metal heads or folkies, post-punk feminists or members of Banana Blender Surprise—has made pop music one of the brightest signals of popular sentiment and cultural transformation of the last forty years.

This proximity to the culture is also what has made pop-music writing arguably the most urgent and politically tinged form of criticism of the same period. Whether it’s Joan Didion reflecting on the determined innocence of youth culture as she wandered through Joan Baez’s Institute for the Study of Nonviolence in the mid-1960s, or Chuck Klosterman writing in the early part of this decade about the meaning of glam metal in the Midwest, music writers have made the case that to write about pop music is to illuminate the zeitgeist.

During those same four decades, pop-music criticism evolved from a fugitive journalistic impulse (as the critic Eric Weisbard has called it) into a fixture of the media firmament. The New York Times, The Washington Post, The New Yorker, and The New Republic employ pop critics, as do regional papers ranging from the Detroit Free Press to The Oregonian to The Sacramento Bee.

Yet, at a moment when the nature of American culture and political identity is in flux, critical writing about pop music has grown steadily more irrelevant. This is in part a consequence of the pressure the Internet has exerted on journalism at large: the venues are shrinking, along with the fees and the audience. But these problems have been especially acute for music writers, because the Internet has simultaneously undermined their utilitarian function as consumer guides by making music free. As Ann Powers, the chief pop-music critic at the Los Angeles Times, put it to me: What value is there in writing that the latest Metallica album is good, when readers can log onto the band’s MySpace page, listen for free, and decide for themselves? It’s not as though one needs to be an ethnomusicologist to determine that “Enter Sandman” rocks.

Jacob Levenson is a writer who lives in Brooklyn. He is the author of The Secret Epidemic: The Story of AIDS and Black America.