Our era is known as the Age of Terror, and no wonder. Twelve years ago, the United States suffered its worst terrorist attack ever, and since then, we have lived under the shadow of atrocities designed to frighten as well as kill. The bombs that went off in Boston put to rest the hope that with al-Qaida largely demolished, we could rest easy.
This episode was a gruesome reminder of the toxicity of political extremism and our vulnerability to it. There are people out there who want to kill innocent Americans, and there is no reliable way to stop them all. The question looking back is: Who did it? The question looking forward is: What's next?
But horrifying though the Boston attack was, we don't really live in an age of terror. In relative terms, believe it or not, it's really an age of peace and safety. We are not immune to radical violence. But we have far less of it than we used to.
Back in 1993, al-Qaida operatives set off a truck bomb in the basement of New York's World Trade Center, killing six and injuring more than 1,000. Two years later, Timothy McVeigh detonated explosives at the federal building in Oklahoma City, leaving 168 people dead.
Those were preludes to the horror of 9/11. But since then, terrorism has not proliferated -- just the opposite. From 1991 through 2000, reports the National Consortium for the Study of Terrorism and Responses to Terrorism at the University of Maryland, the United States had an average of 41 terrorist attacks per year. From 2002 through 2010, the number was just 16 per year.
Even the 1990s were nothing compared to the 1960s and 1970s, when homegrown terrorism reached epidemic levels. The violence came from both the right and the left. The Ku Klux Klan assassinated civil rights leader Medgar Evers and killed four black girls by blowing up a church in Birmingham, Ala. Anti-Castro militants committed dozens of bombings in Miami.
The Weather Underground mounted its own campaign of bombings, including blasts at the U.S. Capitol, the Pentagon and the State Department. In 1970, antiwar radicals destroyed a University of Wisconsin science lab and killed a postdoctoral researcher.
"Bombing has reached gigantic proportions," New York City's police commissioner told Congress. The New York Times reported, "From January 1969 to April 7, 1970, the country suffered 4,330 bombings" that caused 43 deaths.
Not all leftist radicals joined in. "Sniping," noted The Times, "appears to be the preferred style of violence for black militants."
The volume of mayhem is hard to imagine in our more peaceful age. The trend over the past few decades has been away from the use of physically destructive means to achieve ideological ends.
How come? It's not because we have more police or better crime-fighting technology, though those help. It's a reflection of an often polarized but essentially healthy political culture. Murderous movements simply don't flourish in modern America. A soil that is ideal for robust and often vitriolic debate offers little sustenance to the weeds of violent extremism.
In the weeks after 9/11, it was widely assumed that terrorist attacks and suicide bombings would proliferate within our borders. But al-Qaida didn't inspire a legion of followers and imitators any more than McVeigh did. The uprisings they hoped to produce never ignited. American Muslims almost unanimously rejected the call to religious war, even after the U.S. invaded Afghanistan and Iraq.
A big reason for the ebbing of violence is that American society has come so far. In the 1960s, blacks suffered severe discrimination and had little political power. During the Vietnam War, 18-year-olds were forced to risk death for a cause many rejected. The second-class status of women fueled political alienation. Protests often evoked brutal responses from police.
Those festering social ills have vanished or subsided. America is a freer and more open place for people of all kinds. Even Muslims are not less satisfied with the direction of the country than their neighbors: They are more satisfied.
Our political rhetoric is sometimes irresponsible. But the safety valve of untrammeled free speech seems to keep it from turning into actual violence. Fire-eaters can engage in political theater without proceeding to incendiary action.
Those who resort to killing innocents achieve nothing but the defeat of their own cause. Americans have no sympathy for political violence. And that's a pretty good inoculation against it.