I was in a classroom in Richardson, Texas when President Kennedy was shot. Yesterday, I was sitting on a train heading into New York when one of the most despicable acts in United States history took place.

Looking out the window to my right, I saw a long, huge plume of smoke floating away from the twin towers of the World Trade Center. When I saw that unforgettable sight, I knew that I must not go any farther, and got off at the next station to turn back toward home.

As I was walking to my track, a stranger stopped me and said in disbelief that one of the towers had collapsed. At first, I could not comprehend what he meant. By the time my train arrived at my home station, the second tower had fallen to the ground. We spent most of the day trying to locate a dear friend who worked there.

The authorities tell us that this is terrorism. Terrorism is defiance of the rule of law. The immediate suspects on the news were religious extremists, in particular Osama bin Laden, but many remind us that we assumed the Oklahoma City bombing was the product of Arab extremists until we learned it was perpetrated by American white supremacists.

Religious or not, extremists who care nothing for the usual rules of behavior, or for any particular human being, perpetrated these tragedies.

The Need for the Moderation of the Mainstream

Moments like these remind us that there is no liberty or life without law, and there is no law without mutual social agreement to obey it. We hear a lot these days about the "secularization" of American society, but one has to ask whether social forces that trim the sails of extremism are really bad for society. A key to our success may lie in the moderation of the mainstream.

Before dismissing these extremists as wholly atypical, it must be remembered that there is no major religious tradition that has not been involved in a holy war. It is a horrible reality–proven again and again in history and around the globe–that a sense of religious truth and righteousness has the power to motivate believers to kill hundreds and thousands of innocent victims. A tremendous force for good, religious fervor also finds its way down darker corridors.

The Limits of Law — and Its Reach

Here is where law meets its limits. At the moment of anarchical action, the law is impotent. The Constitution was meant to deter power grabs — including the attempt to acquire power through violence — and to channel the exercise of power in the society toward the greater good. But it cannot inoculate us against all evil.

The Framers fundamentally understood that the management of power is the locus of liberty and that if power is dispersed, divided, and checked, liberty and happiness may take root. They also knew that even with their constitutional innovations, some would be sorely tempted to abuse their power in ways that hurt others. Of course, they were well-schooled by the history of religious, feudal, and monarchical wars in Europe before the founding.

While the extremists this time accomplished their horrendous deed with grotesque success, they could not make the law vanish. The United States Constitution crafted a system that is durable and strong, with a President holding the power to command a formidable military to counterattack, and an investigative, prosecutorial system that is seeking out these criminals and that will "punish them," to use the President's words.

We marveled in December at a constitutional structure that kept this country peaceful and united in the midst of a befuddling presidential election, but that was a walk in the park compared to now.

Extremists are the true test of the Constitution's capacity to craft a working constitutional order. This constitutional order is already imposing order–an order that requires a declaration of war against extremists–on the anarchy these most recent extremists attempted to seed.