In the days since Anders Behring Breivik — the accused perpetrator of Friday’s deadly attacks in Norway — has been identified as a Christian right-wing extremist, some liberals in the US have descended on the episode as another opportunity to draw a straight line between hard-right political causes and actual violence. The meme has been gaining steam since the early rise of the Tea Party, a group that occasionally celebrates its Second Amendment gun rights by toting weapons to public rallies.

“Norway, US, Worldwide — is Right-Wing Violence endemic?” asks a blog post on the popular liberal Internet enclave Fire Dog Lake. Explains the writer:

“Right-wing supporters, here in the US and around the world, have a long history of resorting to, or actually embracing, violence. People from politicians, to preachers to doctors have all been shot because of their perceived (and perhaps real) left leaning political views.”

The author then proceeds to compile a list of recent incidents involving right-wing violence, including mention of the January shooting of Democratic congresswoman Gabrielle Giffords.

ThinkProgress, a liberal blog affiliated with the progressive Center for American Progress, has published an oddly beside-the-point revelation that the “Norway Terrorist is a Global Warming Denier“, as if this contributes further damning evidence of the ideological similarity between mass murderers and run-of-the-mill conservatives. In another post, the blog cites “evidence that [Breivik] was a fan of far-right bloggers and political parties.”

It then uses the occasion to chastise Rep. Peter King, who has refused to include homegrown terrorism threats – read: threats from neo-Nazis and other domestic right-wing extremists — in his congressional hearings investigating the radicalisation of American Muslims. King, since the Norway attacks, has held to that position.

Of course, it would be preferable for King to abandon the hearings all together rather than to add domestic political partisans to his already dubious investigation of the Muslim community. But the hint of “endemic” right-wing violence poses a different challenge – and that’s that we head down a tricky path in trying to draw systemic conclusions about political ideology and specific incidents of bloodshed.

It’s possible — as has turned out to be the case with Giffords’ shooter — that the defining characteristic of Breivik and other such violent rogues isn’t their politics, but their mental instability. And conflating the two could be problematic for political speech in the long run.

Sarah Palin was widely indicted after the Giffords shooting, which left six dead in an Arizona strip-mall parking lot, for having produced a map of political opponents targeted in the 2010 election with gun-sight symbols over their districts. Pundits speculated that such a map could have motivated Jared Lee Loughner to take Palin’s suggestion literally. (Subsequently, there was no evidence Loughner ever even saw Palin’s campaign graphic.)

Since then, Americans have been struggling mightily with the consequences of political discourse, with what it means to be “civil” at a time of rising political acrimony, and with the murky causal connection between words, ideas and violent action. It’s an important discussion. But chalking up the Norway shooting as another example that “right-wing ideas = violence” doesn’t add much to it.

Joshua Foust, writing in The Atlantic, is equally firm on this point:

“In order to tar all of Europe’s right, even just the upsetting xenophobes clothing themselves in worry about jihad, you must demonstrate a causal mechanism by which concern over cultural outsiders becomes murderous rage against the very people you claim to protect (in this case, ethnic Norwegians). Without being too trite, it requires an especially deranged mind already far outside the mainstream to decide to slaughter children at summer camp just because it is run by a left-wing political party. Associating that sort of mentality with the mainstream is not just wrong and lazy, it is hypocritical.

Indeed, much of the Western’s left’s quasi-triumphalism over the Norwegian tragedy revolves around it’s complete non-relationship to Islamic terror. Here, so many seem to celebrate, is the proof they had finally sought that right-wing politics are not just annoying and wrong, but actively dangerous.”

That argument may be politically profitable in the short term. But in the long run, suggesting political beliefs — whether liberal or conservative — are synonymous with incitement to violence could wind up undermining the rights of even those making such an argument today.