And that seems to be a big part of what bothers the fact-checkers. In their year-end write-ups, both Politifact and point to an inflammatory ad produced by a liberal advocacy group that shows an elderly senior citizen being dislodged from her wheelchair and dumped over the side of a cliff. It was something of an odd choice, as an earlier Politifact item on the ad itself found its claim that the GOP plan would “privatize Medicare” to be “mostly true.” (A separate item found the ad’s assertion that the plan would leave the country “without Medicare” to be “false.”) But the ad’s outrageous imagery buttresses a larger point the fact-checkers want to make: the “end Medicare” line was a bit of Democratic demagoguery designed to scare seniors, which has no place in responsible political debate.

Similarly, Kessler began a broadside against a Democratic group’s anti-Mitt Romney attack ad by bemoaning the disappearance of “civil discourse in politics.” And while his post faulted the ad for alleged inaccuracy, notions of accuracy and civility can be wound together. Among other things, Kessler faults the ad for using footage of Romney saying, “Don’t try and stop the foreclosure process. Let it run its course and hit the bottom,” because Romney’s initial remarks had included a fuller explanation of his argument, which was omitted from the ad. Adding that extra context might have been more civil to Romney, but the ad accurately quoted what he said, and, more importantly, what he said is what he meant—more context might have added nuance, but it wouldn’t have changed meaning. As with Pawlenty and Paul, whose arguments were faulted because they hadn’t been validated by a particular arbiter, these ads represent political speech that is deemed by the fact-checkers to be in some way illegitimate.

Though I think the fact-checkers’ ideas about what constitutes legitimate discourse are, at times, dangerously narrow, I’m not as troubled by this impulse as are critics like Greenwald and Hemingway. For one thing, a lot of what makes it into these not-quite-fact-checks is useful information that provides important context about what politicians are saying. For another, the work of the press is (like the work of any profession) necessarily value-laden, and as values go, promoting civil political discourse isn’t a bad one.

But here’s where the fact-checkers find themselves in a box. They’ve reached for the clear language of truth and falsehood as a moral weapon, a way to invoke ideas of journalists as almost scientific fact-finders. And for some of the statements they scrutinize, those bright-line categories work fine.

A project that involves patrolling public discourse, though, will inevitably involve judgments not only about truth, but about what attacks are fair, what arguments are reasonable, what language is appropriate. And one of the maddening things about the fact-checkers is their unwillingness to acknowledge that many of these decisions—including just what constitutes “civil discourse”—are contestable and, at times, irresolvable.

Politifact and its peers can call the “end Medicare” line a “lie” all they want and never convince anyone who doesn’t see it that way, because there’s no empirical disagreement at issue, and there’s nothing in the journalistic toolkit that can confer ultimate authority about the questions that are in dispute. You can’t report your way to the conclusion that it’s okay to say, as leading Republican Mitt Romney has, that the GOP plan will “fundamentally transform Medicare,” and basically okay to say, as President Obama has, that the plan would “end Medicare as we know it,” but that it’s an egregious falsehood to simply say it would “end Medicare.” The argument about the legitimacy of that language is ultimately political, not journalistic, in nature. By insisting otherwise, and acting as if journalistic methods can resolve the argument, the fact-checkers weaken the morally freighted language that’s designed to give their work power—language that all journalists who are able to report their way to authority on a particular subject need to employ when it is justified.

Greg Marx is a CJR staff writer. Follow him on Twitter @gregamarx.