Yesterday, tragedy hit Austin, Texas, the place where I'd lived for 14 years and only moved away from two months ago. A man tentatively identified as 53-year-old Joseph Stack, flew his small plane into the seven-storey IRS building in North Austin, after setting fire to his own home and leaving a lengthy suicide note on his website. The note was surprisingly lucid for a man committing an act universally seen as crazy, and it spelled out his mostly political grievances, with a call to arms at the end for those who share them. And yet, many commentators and the US government are reluctant to call this a terrorist act, though it fits neatly within the FBI's definition of domestic terrorism. They shouldn't be, because Stack did this in the cultural capital of paranoid politics.

Part of the reluctance to define this as terrorism is the fact that Stack's politics don't map out neatly on the partisan landscape of the US, unlike the politics of other domestic terrorists such as abortion doctor killers and rightwing extremists like Timothy McVeigh. Stack complained about his taxes, but he also complained about the inability of politicians to reform the healthcare system. Without a coherent ideology to pin on him, most people had trouble seeing Stack as a terrorist. But I recognised his type immediately, having lived the majority of my life in the area. Call them the nihilists or the political paranoids, but Austin and the surrounding areas of Texas are the cultural centre for a certain brand of paranoid politics that stretches far beyond partisanship and sees enemies and conspiracies around every corner. They hated Bill Clinton, but they hated George Bush, too. They're mostly very conservative, but they attract left-leaning paranoids, who share their affection for conspiracy theories. Stack indicated in his note a long relationship with the political fringe, going back to participating in anti-tax schemes in California.

Sure, Austin is mostly known as a Democratic stronghold. But if you live there for even a short period of time (as Stack had), you can't miss the paranoid culture. The biggest media empire in the US for disseminating unhinged conspiracy theories is located in Austin. The website for this empire is Infowars, and the radio show that's broadcast to over 60 stations nationwide is called the Alex Jones Show. Jones's politics are ostensibly libertarian-conservative, but really, his ideology is paranoia. His empire sucks in rightwingers with conspiracy theories that feed the militia gun culture, but they also love conspiracy theories that appeal more to the left, such as the belief that 9/11 was an "inside job". And then there are unclassifiable ones, such as the belief that gatherings of elitist power players at the Bohemian Grove are actually Satanic rituals.

Jones is a local celebrity in Austin, treated indulgently if not taken too seriously. You can be reasonably certain that someone with unhinged beliefs like Stack was aware of the strong culture of political paranoia in the area when he committed this terrorist act. Most places in the country, his call to arms would come across as simply ineffectual. But central Texas is where the conspiracy theories that inspired Timothy McVeigh to blow up a federal building in Oklahoma take root and spread like weeds. I predict the conspiracy theory machine is already working overtime to produce some narrative blaming this on the government and painting Stack as a victim, if not a hero. Facebook groups have already started to pop up celebrating Stack as a tax protester. Because of this, we cannot write Stack off as a lone wolf. Just because he likely didn't conspire with others directly doesn't mean he wasn't sending off a signal to the paranoid malcontents of America. And they are listening.