To be sure, any factual arguments reflect particular values or perspectives. And critics from the right, like those on the left, say that undermines the factcheckers’ claim to neutrality. In response to PolitiFact’s previous “Lie of the Year” selection—conservative claims that Obamacare was a “government takeover of healthcare”—the Wall Street Journal editorial page complained that, “in reality PolitiFact’s curators also have political views and values that influence their judgments about facts and who is right in any debate.”

Well, yes. The shape of the world matters; facts take on particular meaning depending on the political context. But the “government takeover” analyses at PolitiFact and couldn’t have been clearer. They pointed out that the new health-care rules rely entirely on—and will actually expand—the private insurance market. Obamacare doesn’t feature public doctors like Britain’s NHS, or public insurance like Canada’s single-payer system. It doesn’t even have a “public option.” As welfare states go, that’s pretty weak tea. The factcheckers made a convincing argument about how reasonable people would interpret the phrase “government takeover” in light of conventional linguistic usage and the real political-historical context in which that language is embedded. We have lots of actually existing examples of what government-run healthcare looks like, and Obamacare ain’t it.

Factcheckers did the same thing in the “end Medicare” episode, applying a kind of Occam’s Razor to the phrase—though it can be hard for people (like me) who favor a larger government role in healthcare to see that. Here’s the logic: If Ryan’s privatization plan ends Medicare, what would we say of a proposal that actually ended it? Of course a scheme to give seniors two free aspirin a year and call it Medicare would count as killing the program, as Chait mused; but does everything short of that fall into some hazy, undifferentiated sphere of personal opinion?

It’s ironic that these journalists now take so much heat for making factual arguments. Not long ago one of the most common, and persuasive, critiques of the media—especially from the liberal blog set—was that journalists refuse to scrutinize political rhetoric beyond the “horse race.” The factchecking movement is a response not just to outlandish political claims but to the false balance and “he-said, she-said” journalism that publicized those claims uncritically. A kind of reporting that rethinks objectivity has to interpret evidence and draw conclusions. We can’t ask reporters to be more fearlessly assertive and analytical and then expect their conclusions always to agree with ours.

A subtler critique is that factcheckers go astray when they venture into “uncheckable territory,” as Greg Marx put it in a lucid take on the “end Medicare” brouhaha. Building on an analysis by Jay Rosen, Marx tries to mark off that territory by erecting a fence between arguments about truth and about legitimacy, which a project rooted in the language of fact and falsehood should steer clear of:

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.

But things get tricky here, too. Marx concludes (and Rosen agrees) that “you can’t report your way to the conclusion” that the GOP plan does or doesn’t end Medicare. The dispute turns on politics, not factual evidence. But by the same logic you can’t strictly report your way to the conclusion that the Affordable Care Act doesn’t take over the healthcare system. Your can’t report your way to finding that President Obama didn’t go on an “apology tour,” or that he didn’t propose to “gut welfare reform,” or (to take a contrary example) that Mitt Romney never “backed a law” to ban all abortion.

All of these conclusions rest on subtle judgments about what arguments are reasonable and what language is appropriate. Even in technical matters, “true” and “fair” quickly get tangled up. Take a simple question: How many millionaires don’t pay federal income taxes? Sen. Harry Reid said the number was 7,000 for 2011, and earned two Pinocchios from The Washington Post. It turns out there’s more than one way to count millionaires, so there’s no truly value-free way to rate the claim true or false. These are the kinds of unstable facts the factcheckers work with all of the time. They navigate a messy political economy of information in which there’s always more than one standard to choose from, and experts and data sources inevitably come with some bias.

Lucas Graves is an assistant professor in the school of journalism and mass communication at the University of Wisconsin. Follow him on Twitter at @gravesmatter.