What is the best way for terrorists to wreak havoc in the United States? That was the question posed, and answered, yesterday on the New York Times website by Steven D. Levitt, the University of Chicago professor of economics and author of the best-selling book, Freakonomics.

Levitt’s advice to al Qaeda, based upon the economic principle of generating the greatest quantity of harm with the least possible input of resources, would be to learn from the Washington D.C snipers of 2002. He suggests arming

20 terrorists with rifles and cars, and arrang[ing] to have them begin shooting randomly at pre-set times all across the country. Big cities, little cities, suburbs, etc. Have them move around a lot. No one will know when and where the next attack will be. The chaos would be unbelievable, especially considering how few resources it would require of the terrorists. It would also be extremely hard to catch these guys. The damage wouldn’t be as extreme as detonating a nuclear bomb in New York City, of course; but it sure would be a lot easier to obtain a handful of guns than a nuclear weapon.

This does indeed sound like a terrifying scenario and perhaps there is a terrorist cell hidden here that will carry it out.

Levitt believes that putting such suggestions in print for terrorists to read is “a form of public service.” By thinking of plausible ways of causing violent destruction, he writes, “it gives terror fighters a chance to consider and plan for these scenarios before they occur.”

Levitt’s column generated what he says today, in a subsequent posting on the Times website, was an immense amount of hate mail: “The people e-mailing me can’t decide whether I am a moron, a traitor, or both.”

But there are also quite a few letters on the site applauding Levitt, like this one from a person who identifies herself simply as Kelly: “I think you are doing a terrific job actually THINKING about our situation rather than reacting like so many of our fellow Americans.”

Is Levitt indeed performing a public service, or is he a moron, traitor, or both?

Answering this is not as easy as it might appear at first glance. The fact is that we do need to think carefully about the manifold ways terrorists might attack us again. The U.S. government has failed abysmally at that task in the past.

In his memoir, At the Center of the Storm, CIA Director George Tenet recalls with some pride how on the evening of September 12, 2001, he was sitting in his office “kicking around ideas” with a senior agency official when they hit upon the idea of creating “a group with the CIA whose sole purpose in life would be to think contrarian thoughts.” Such a unit, duly created by Tenet and dubbed the “Red Cell,” was given the assignment of “speculat[ing] on what was going through Osama bin Laden’s mind.”

In other words, up until September 11, it never occurred to the clueless Tenet or anyone else in a position of responsibility at our premier intelligence agency to perform the elementary task of thinking systematically about how our terrorist adversaries were thinking about us, including about how they might attack us.

There is thus a case for a public discussion of the issue raised by Levitt. But raising the issue and generating actual scenarios in public are two different things. Levitt defends himself on this point by noting that “a lot of the angry responses [he received made] me wonder what everyday Americans think terrorists do all day. My guess is that they brainstorm ideas for terrorist plots. And you have to believe that terrorists are total idiots if it never occurred to them after the Washington D.C. sniper shootings that maybe a sniper plot wasn’t a bad idea.”

True enough. Or is it true at all?

Yes, there are terrorist masterminds out there who do not need our help cooking up the most intricate and lethal plots against the United States. The attacks of September 11 alone are sufficient evidence of that.

But there are also more than a few terrorists and would-be terrorists roaming around who might qualify as “idiots,” or something close. Most recruits for terrorist action in the Islamist cause are not sophisticated planner types like Khalid Sheikh Mohammed but angry, ignorant, low-level figures, used by the higher-level terrorist plotters as expendable “muscle.”

Richard Reid is one such figure. If he had been smart enough to set off his shoe-bomb in the privacy of the bathroom instead of while remaining in his seat, American Airlines Flight 63 might now be resting quietly on the bottom of the Atlantic Ocean with all of it 197 passengers and crew.

Then there was Zacharias Moussaoui, who was encountering trouble in his Minnesota flight school. This deranged fanatic might have only needed scant prompting, perhaps by stumbling across a clever scenario cooked up by Steven Levitt, to find a way to work al Qaeda’s will that was easier than poring through aviation manuals and struggling to operate a Boeing 747 simulator.

There was also el Sayyid Nosair, an operative in the nascent al Qaeda operation, part of the band that was to attack the World Trade Center the first time around in 1993. In 1990, Nosair spent his time and energy planning and carrying out the assassination of the firebrand rabbi Meir Kahane. Given the combination of Kahane’s extremist views and marginal status, this act was senseless, and even counterproductive, from the point of view of Nosair’s own cause. In choosing his victim, Nosair could well have used some help from an economist like Levitt. Will Levitt now offer to provide a public list of superior human targets, whose deaths would be far more useful to the Islamist cause? The logic of his argument suggests that the answer would be yes.

But beyond the logic or illogic of Levitt’s argument, there is something else. Thousands of Americans died on September 11. Although Levitt minimizes the dangers that lie ahead, blithely writing that his guess is that “the terrorism threat just isn’t that great,” the fact is that, like everyone else, he does not know what he does not know. It is entirely possible that the United States will be hit again, and hit harder than we were on September 11.

To Levitt, however, this solemn subject is not solemn at all. He writes about it in a glib and flippant tone, as in his summons to the public to come up with even more lethal scenarios by which al Qaeda might wreak death and destruction on the United States: “I’m sure many readers have far better ideas. I would love to hear them.”

One of the better ripostes to Levitt on the Times website came from a reader named Steve: “Sir, unable to determine if you are demonic, but your actions are demonic. Contemplate this name, Christine Lee Hanson.”

Christine Lee Hanson was a two-year old who perished on board United Airlines Flight 175 when it plowed into the World Trade Center on September 11.