Mainstream-media political journalism is in danger of becoming increasingly irrelevant, but not because of the Internet, or even Comedy Central. The threat comes from inside. It comes from journalists being afraid to do what journalists were put on this green earth to do.

What is it about Jon Stewart and Stephen Colbert that makes them so refreshing and attractive to a wide variety of viewers (including those so-important younger ones)? I would argue that, more than anything else, it is that they enthusiastically call bullshit.

Calling bullshit, of course, used to be central to journalism as well as to comedy. And we happen to be in a period in our history in which the substance in question is running particularly deep. The relentless spinning is enough to make anyone dizzy, and some of our most important political battles are about competing views of reality more than they are about policy choices. Calling bullshit has never been more vital to our democracy.

It also resonates with readers and viewers a lot more than passionless stenography. I’m convinced that my enthusiasm for calling bullshit is the main reason for the considerable success of my White House Briefing column, which has turned into a significant traffic-driver for The Washington Post’s Web site.

I’m not sure why calling bullshit has gone out of vogue in so many newsrooms — why, in fact, it’s so often consciously avoided. There are lots of possible reasons. There’s the increased corporate stultification of our industry, to the point where rocking the boat is seen as threatening rather than invigorating. There’s the intense pressure to maintain access to insider sources, even as those sources become ridiculously unrevealing and oversensitive. There’s the fear of being labeled partisan if one’s bullshit-calling isn’t meted out in precisely equal increments along the political spectrum.

The return of Democrats to political power and relevancy gives us the opportunity to call bullshit in a more bipartisan manner, which is certainly healthy. But there are different kinds of bullshit. Republican political leaders these past six years have built up a massive, unprecedented credibility deficit, such that even their most straightforward assertions invite close bullshit inspection. By contrast, Democratic bullshit tends to center more around hypocrisy and political cowardice. Trying to find equivalency between the two would still be a mistake – and could lead to catty, inside-baseball gotcha journalism rather than genuine bullshit-calling.

If mainstream-media political journalists don’t start calling bullshit more often, then we do risk losing our primacy — if not to the comedians then to the bloggers.

But here’s the good news for you newsroom managers wringing your hands over new technologies and the loss of younger audiences: Because the Internet so values calling bullshit, you are sitting on an as-yet largely untapped gold mine. I still believe that no one is fundamentally more capable of first-rate bullshit-calling than a well-informed beat reporter – whatever their beat. We just need to get the editors, or the corporate culture, or the self-censorship – or whatever it is – out of the way.