Welcome to the age of post-truth journalism.

Glenn Kessler, the resident fact checker at The Washington Post, took Republican Presidential nominee Mitt Romney to task last month for continuing to accuse President Obama of going on an “apology tour,” writing with clear exasperation: “Despite earning Four Pinocchios for months, Romney keeps saying this.”

Kessler's lament neatly sums up the problem of post-truth politics, a problem that has plagued the political press throughout the campaign, as pants-on-fire falsehoods accusing Obama of ending welfare work requirements, and four Pinnochio fabrications about Medicare funding were repeated on a loop en route to a Republican National convention built on the “you didn't build that” lie and focusing on Paul Ryan's fact-free convention speech.

Put simply by Boston Phoenix political journalist David Bernstein:

More important for media professionals: What do you do when people employed by your own media outlet practice post-truth journalism? What if the entire news media, including your own in-house fact-checker, has called out your colleague's lie, but he keeps pressing it? Now what?

Washington Post columnist Marc Thiessen, a former speechwriter for President George W. Bush, came under fire this week over a self-evidently false attack in the Post questioning President Obama's commitment to national security.

The central claim in Thiessen's September 10 column was that Obama has not prioritized national security. Thiessen's evidence was a report (a report, it later turned out, that he commissioned) claiming that Obama has not attended half of his daily intelligence briefings.

The column itself was self-defeating: Thiessen acknowledged in the column that Obama reads his intelligence briefing every day, quoting a spokesman for the National Security Council who said that Obama “reads his [security briefing] every day.” All Thiessen is quibbling over is whether Obama has his briefing dictated to him, or whether he reads it.

Perhaps book on tape would satisfy the Post scribe?

Thiessen's self-evident falsehood, published in the Post, became fodder for a Karl Rove ad, at which point Kessler weighed in, giving the “bogus” and “misguided attack” three Pinnochios.

Thiessen quickly thumbed his nose at the Post's fact checker

And Thiessen is not alone in the Post's stable of post-truth columnists. In a September 28 column, Charles Krauthammer claimed that Obama's entire Middle East foreign policy has been built on apologies - the very basis of Kessler's exasperated Aug. 30 critique of Romney.

Despite earning four Pinnochios for months, the Post keeps printing this?

Grist's David Roberts, one of the first bloggers to use the term “post-truth politics” explained the problem this environment creates for journalists:

A key feature of the post-truth political landscape is that there are no longer universally recognized arbiters or referees of fact. The right has their own media ecosystem. Why should they care what journos outside it say?

Shouldn't media organizations at the very least care what the in-house fact-checkers say?

That, of course, assumes there are any in-house fact checkers.

After Newsweek came under scrutiny in August for publishing a Niall Ferguson column riddled with falsehoods, attention turned to fact that Newsweek doesn't maintain a fact-checking department and instead relies on their writers to be factual and accurate. Even when those writers are acknowledged Romney supporters.

In response to the Newsweek controversy, The Atlantic's Ta-Nehisi Coates wrote in defense of fact-checking:

When I worked at Washington City Paper there was a hard rule about a writer's errors per year ratio. You get one wrong, you were invited in for an unpleasant chat. You got another wrong, you were invited in for a more unpleasant chat and you went on probation. You got another wrong and you were shown the door.

Coates' words ring particularly true this week: can a media entity like the Post deploy a model of fact-checking that has no apparent accountability?

Earlier this year, then-New York Times public editor Arthur Brisbane sparked a spirited debate when he questioned whether journalists should be expected to act as truth vigilantes. The consensus among media observers was that journalists should, in fact, strive to ascertain the truth behind claims that they print or broadcast.

Perhaps the more pertinent question is: how do media hold their own publications accountable to the facts?