Let’s stipulate that Jared Loughner’s mind is a dark and twisted maze. And that he was driven to violence by feverish compulsions, not a political cause. And that his conception of politics fits no recognizable framework. Even so, his rampage should still encourage everyone in the political arena to look in the mirror.

Here’s one reason: Everyone who deals in hyperbolic political rhetoric was only a mouse click from disaster after Loughner’s attack. Yes, there’s no evidence that he drew direct inspiration from any particularly incendiary political language on the Internet (or elsewhere in the media). But if he had, the source of that rhetoric (whether Left or Right) would pay an enormous political price. This should remind all of those dealing in militant language that they are at the mercy of their least stable followers.

That’s the self-preservation case for self-reflection. The civic argument is even more urgent. Those who feel alienated enough to commit violence against political leaders will always be outliers; but they do not exist entirely independent of a media and political culture in which opponents now routinely portray the party in power as a risk to the nation’s core principles. Usually that inspires political activism; at the extreme, it can contribute to violence.

Throughout American history there has always been a portion of the opposition that views the president and the governing party as not only misguided or ineffective but also fundamentally un-American. “That runs like a red thread through American history,” says Sean Wilentz, a historian at Princeton University who has written extensively on American political debate. The mid-19th-century Whigs considered Andrew Jackson an executive tyrant who would shred the Constitution; many white Southerners viewed John F. Kennedy and Lyndon Johnson as tyrannical for dismantling segregation.

So, vitriolic opposition to a president and his party is not new, but it may be more prevalent today. In modern American politics, it’s always apocalypse now. During George W. Bush’s presidency, opponents said that his national-security agenda amounted to “war crimes.” The liberal group MoveOn.org (in)famously labeled Gen. David Petraeus as “General Betray Us.”

All of this was merely the overture for a more raw and relentless conservative attack on President Obama and the Democratic Congress. Glenn Beck has said that Obama “has a deep-seated hatred for white people.” Republican Rep. Paul Broun of Georgia described former House Speaker Nancy Pelosi as one of the “domestic enemies of the Constitution.” Newt Gingrich declared: “The secular socialist machine represents as great a threat to America as Nazi Germany or the Soviet Union once did.” Imagine that: a Wehrmacht of literature professors massing on the Charles.

Bombarded by this rhetoric, an increasing number of Americans now routinely believe, as Theodore Roosevelt once declared in a moment of excess, that they “stand at Armageddon and … battle for the Lord” against forces of darkness in the other party. After Bush’s reelection in 2004, one psychiatrist told the Los Angeles Times that for some of her patients, the event was “a worse trauma than 9/11.” Obama’s victory has triggered an even greater eruption of overheated conservative alarm. The tea party’s crusade to “take back our country” assumes that Obama is transforming it into something unrecognizable.

In fact, the stakes in our political debates, though substantial, are rarely so large. The parties’ visions are distinct but not so disparate that they risk a rupture with American tradition. Each side operates along the continuum of debate over the proper balance between government and the private sector that has shaped American politics since Alexander Hamilton and Thomas Jefferson. This isn’t arm-wrestling between Karl Marx and Friedrich Hayek.

That’s not what Americans hear anymore. Instead, no matter which side holds the Oval Office, the president’s opponents routinely tell their followers that he represents a threat to the country’s foundational beliefs. One result is that the share of Americans who say they strongly disapprove of the president is systematically rising. Ronald Reagan was certainly a controversial leader, but in 70 ABC  News/Washington Post polls during his presidency, only four times did as many as 30 percent of Americans say they strongly disapproved of him. Under George W. Bush, the number soared to 63 of 112 polls. So far, Obama has faced strong disapproval from that many Americans in 12 of the 20 ABC/Post polls during his presidency. In the exit poll during November’s election, a striking 49 percent of white voters said they strongly disapproved of Obama.

The apocalyptic strain in modern politics means, as Wilentz notes, “you no longer disagree with the person; the person is a threat to the very existence of the country and its values.” For most people, even such excessive rhetoric provokes nothing more than shaking a beer can at a cable blowhard, or waving an angry sign at a town meeting. But when political arguments are routinely framed as threats to America’s fundamental character, the odds rise that the most disturbed among us will be tempted to resist the governing agenda by any means necessary.

This article appeared in the Saturday, January 15, 2011 edition of National Journal.

Want to stay ahead of the curve? Sign up for National Journal’s AM & PM Must Reads. News and analysis to ensure you don’t miss a thing.