Not so today. What’s different now, of course, from the ecology of the ’50s—or the ’60s, or the ’70s, or the ’80s, or the ’90s—is the sheer size of the media ecosystem, and the sheer number of species populating it. The more news outlets there are, in turn, the more choice each outlet has about which information to dig up and to share—and the less reason it has to relate its diggings and sharings to a broader cultural framework. To a theme.

How, after all, in a world teeming with competing versions of reality, are we supposed to know what to believe? In all the white noise, how do we ensure that we’re filtering what we need to hear?

In that disruptive sense alone, the Web—the protean force of the digital age, the platform that has introduced the tumult and turbulence of media proliferation—has been revolutionary. There has always been more information in the world than there have been news outlets to convey it; but the explosion of outlets, in particular, means that no longer is slant the key self-definitional distinction in news: “I read Daily Kos, so I get my news from a liberal perspective.” Now, the key distinction is about fact: “I read Daily Kos, so I get news that is liberal.” Kos provides its community, often, with completely different information than, say, the National Review Online, or Drudge, or The Washington Post, provide their communities. “The news” itself, as a unitary entity, is no longer something we can take for granted. On the contrary: it is increasingly incoherent—“a mass of niches,” Jeff Jarvis has it. Indeed, the notion of a master narrative itself—the communal melody that, even in its exclusivity, also binds us together in its tunes and tones—is slowly dissolving into white noise.

Again, this isn’t all bad: the benefits of diversity and democratization are clear, and nearly countless. Nor is it all new: the anxieties of the echo chamber are older than the Web itself. But they’re also simplistic. Echo chambers and their ilk, after all—for all their informational exclusivity—also foster, in their very narrowness, passionate beliefs among those who participate in them. And passionate beliefs are good—and necessary—for, among other things, democracy. Beliefs, David Weinberger notes, “aren’t simply propositions to which we assent. They are also the foundation for action and for political solidarity.” And partisan journalism in general, the media scholar Michael Schudson points out, “enlists the heart as well as the mind of the audience. It gives readers and viewers not only information but a cause.”

At the same time, though, echo chambers—even those that many might think of as ‘the good ones’—have an insularity that impedes broader political and cultural discourse. They distort reality through their very presumption of multiple realities. They assume—and, then, foster—a disconnect between sub-truths and, simply, truth. Andrew Leonard put it well when analyzing his shock that the 2004 presidential election—despite the Kerry Confidence of the left-wing blogosphere—ultimately awarded another term to George Bush: “Perhaps if I’d spent less time at Daily Kos and more time talking to people who live in Alabama I’d have been less surprised by the election results,” Leonard writes. “And perhaps I’d be better prepared to deal with them.”

The problem with echo chambers, in other words, isn’t implicit; it’s contextual. Their value depends, as the value of most things depends, on the environment in which they operate: the overall structure of news. And on their ability, in political terms, to balance the will of the minority with the rule of the majority. “I really think I need to get out more, now,” Leonard had it. And: indeed. Niche news is problematic only when the niches are so niche—and so systematized—that diversity itself devolves into cognitive chaos. “Entropy, as loss of meaning,” Orrin Klapp notes, “always lurks at both ends of the continuum from banality to noise.”

Megan Garber is an assistant editor at the Nieman Journalism Lab at Harvard University. She was formerly a CJR staff writer.