Commentators have for years lamented the growing polarization of American politics. Both parties have increasingly turned away from compromise and unreliable centrists and towards “base” elements that personify ideological purism. The ideological purging of heretics began in earnest in 2006 when Democratic activists targeted Sen. Joe Lieberman in the primary as retaliation for his dissent from orthodoxy with regard to the Iraq war. And it now appears that process may have reached a tipping point in both parties as activists in Arkansas, Pennsylvania, Utah, and Kentucky have hounded two incumbents from their seats, defeated a candidate supported by nearly all of his party’s elites, and forced another incumbent into a runoff that will severely weaken her prospects in the general election.

Why? What is the appeal of purist politics? Part of the process may be driven by primary campaigns that are only open to registered party members. As the size of party registrations has dropped and more voters have either dropped out of politics entirely or retreated into a cynical “pox on both their houses” independence, the field has been cleared for purists to flex their muscles in spite of their relatively small numbers. But more important may be the growing attitude of intractable civil war between far right and far left.

As Orson Scott Card observed in his prescient novel Empire, the earliest stage in a civil war is not the war between the two sides, but rather the war between those radicals on both sides that want to have the war and those caught in the middle that would prefer a lesser level of confrontation. Only by extremists on both sides cooperating to increase polarization and force everyone else to choose up sides can they set the condition for the political warfare they want. And their method is demonization — only by convincing relatively moderate sympathizers that the other side is not only wrong, but actually evil can they force the us-or-them mentality.

This most recent evolution of the process can be drawn back to the 1980s, when Reagan was condemned by some opponents not only as misguided in policy, but a “warmonger” who actually wanted to kill off half the planet. The late Senator Ted Kennedy expressed the tone of the time when he took to the floor of the Senate and claimed that Supreme Court nominee Robert Bork wanted women to die. It accelerated through the 1990s, with far-right activists fretting about an evil (Democratic) central government that would seize their guns and put dissenters in concentration camps and far-left activists claiming that Republicans in Congress wanted to “force grandma to live in a ditch and eat dog food”.

All that pales to the dramatic escalation that has taken place in the 2000s. During the Bush administration (and conveniently forgotten by those who think the vicious rhetoric of the “Tea Party” is somehow an exclusive vice of the right wing), far-left commentators and more than a few who made the move toward the mainstream characterized Bush as “Hitler” (or even worse) and mused endlessly about an imminent totalitarian police state. And when Republicans were sent politically packing, “Tea Party” activists, whipped up by the likes of Glenn Beck, have proclaimed the imminent apocalypse of “socialism” from the Obama administration, matched blow-for-blow by Democratic activists unmollified by their political victories and determined to characterize all dissent as “racism” and worse. Literally every single disagreement with the other side has become “lying” and literally every single internal disagreement has become unforgivable betrayal.

The constant escalation from both sides has combined with a reluctance of many mainstream liberals and conservatives to even admit to extremism in their own houses, let alone combat them, lest combating one’s own radicals wind up “giving ammunition to the enemy”. The result is the extremists being able to either capture or marginalize the “mainstream” and seize the stage. They won when the concept of opposition became equated with paranoid notions of “the enemy” in the first place.

The conditions are set for total political warfare. And the strategies, priorities, and agendas are being written wholly by the radicals. Political literature is now dominated by the metaphors of warfare, “fighting” to “save” our side and “stop” the other from “taking” or “stealing” or “raping”.

Hold on to your hats, it’s going to be a bumpy ride — if we’re lucky.