BROOKE GLADSTONE: Every so often we consider words or phrases that percolate up through the media. And one locution that has lately been breaking the waves is mainstream media. An old term with a new hot button status, the supposed decline of the mainstream media is a favorite topic of Fox News star Bill O'Reilly who invokes it here in an interview with PBS' Michael Medved on "The O'Reilly Factor."

BILL O'REILLY: What do you think is going on here inside the mainstream media? You're a talkshow host and you do that. But inside the CBS', NBC's, ABC's do they know there's a culture war raging and how are they handling it?

MICHAEL MEDVED: Well, they're beginning to. But part of the problem is they don't get the religiosity of the American people.

BROOKE GLADSTONE: That's one variant in the meaning of mainstream media, a cauldron of left wing ideology paradoxically out of touch with an increasingly conservative mainstream. Author Bob Kahn, staunch critic of The New York Times put it this way, on The O'Reilly Factor.

BOB KAHN: You know, the mainstream media has had a monopoly over the setting of the news agenda for over 30 years. And now with the advent of talk radio and TV cable, cable news like the Fox News, they don't have that monopoly anymore.

BROOKE GLADSTONE: In this formulation, mainstream media or MSM does not refer to Fox News, America's most watched cable news channel. New York University journalism professor Jay Rosen who authors the blog PRESSthink.org says the term is fatally imprecise, and he's coined his own, legacy media, like the legacy airlines.

PROFESSOR JAY ROSEN: Well they resemble the legacy airlines because they are in a sense saddled with an outdated or heavy infrastructure in an age when to be nimbler and lighter might be a lot better.

BROOKE GLADSTONE: You conceded in your column that the airline industry's legacy carriers have been pretty much given up for dead.

PROFESSOR JAY ROSEN: Right.

BROOKE GLADSTONE: Do you forecast the same fate for the MSM?

PROFESSOR JAY ROSEN: No. But I think they have to realize that adapting to a new world is critical now and that certain notions [LAUGHS], certain standard practices, things they've lived with, grown up with, might in fact be tossed overboard. The philosophy of objectivity and neutrality now has to be stretched over like conflicts in politics that are so deep that the one hand and the other hand reporting, he said, she said, it's like a escape from truth, rather than a measured tone of truth, a kind of a silence that journalists have practiced that others are now filling in.

BROOKE GLADSTONE: We know the networks are mainstream media, and we know the newspapers are mainstream media.

PROFESSOR JAY ROSEN: Right.

BROOKE GLADSTONE: But how about cable? Or is it everybody on the one side is mainstream media, and bloggers, the citizen journalists, the independents on the other side are not the mainstream media?

PROFESSOR JAY ROSEN: When I use the term I mean the professional culture of the press as it extends over a lot of different media outlets. But it depends on where you are in the media food chain, what you mean by mainstream media. That has a lot to do with it. It's a term to designate an other, and especially in blogging that's what it is; it's the other, it's what you're reacting against. It's also what you're reacting to.

BROOKE GLADSTONE: It's "them."

PROFESSOR JAY ROSEN: Yeah. [LAUGHTER] Yeah.

BROOKE GLADSTONE: So as a word it's essentially a moving target.

PROFESSOR JAY ROSEN: A floating signifier, we call it, in the university, yeah.

BROOKE GLADSTONE: And possibly even a product of an increasingly paranoid culture because it seems to me that it's almost always invoked as a pejorative.

PROFESSOR JAY ROSEN: Associations with cluelessness do cling to this term.

BROOKE GLADSTONE: Cluelessness but also extreme capitulation on the left or the right. I mean, when Bill O'Reilly refers to it he talks about a liberal media establishment that's not only out of touch but pernicious. And when people on the left talk about it they talk about one that is wholly owned by corporate interests and the right and is antithetical to the goals of democracy.

PROFESSOR JAY ROSEN: You know Brooke, as we're talking about this it's occurring to me that part of why this term mainstream media came about is that so a lot of different people could say what was ending.

BROOKE GLADSTONE: [LAUGHS]

PROFESSOR JAY ROSEN: The world of the mainstream media began unraveling in the mid-seventies when cable television began to enter American life and this limited range of choices started to expand dramatically. And your Internet came along and took all of those people who for so long had been the audience of the media and connected them to one another. For the year 2004, for people on the cultural and political right, the red state of America [LAUGHS], MSM was a very concrete real, almost sensuous thing. It was not at all an abstraction. And I think people are going to remember 2004 and the politics of that year partially with those initials MSM.

BROOKE GLADSTONE: New York University professor Jay Rosen authors the blog PRESSthink.org.