Commentary on the Fort Hood incident can be categorized three ways: reaction, response, and rejoinder (commentary on the commentary).

Reactions generally consist of pundits pouring their preconceptions over what is known of the facts. These are the least worthy of our time, and rejoinders like this one from Stephen M. Walt of Harvard University in the Fort Hood section of The Politico’s Arena blog dispense with them well:

Of course [Fort Hood] is being politicized; there is no issue that is immune to exploitation by politicians and media commentators. The problem is that there are an infinite number of “lessons” one can draw from a tragic event like this — the strain on our troops from a foolish war, the impact of hateful ideas from the fringe of a great religion (and most religions have them), the individual demons that drove one individual to a violent and senseless act, etc., — and so no limits to the ways it can be used by irresponsible politicians (is that redundant?) and pundits.

My favorite response—by “response,” I mean careful, productive analysis—was written last year as a general admonition about events like this (which at least has terrorist connotations):

Above all else is the imperative to think beyond the passions of those who are hurt, frightened or angry. Policymakers who become caught up in the short-term goals and spectacle of terrorist attacks relinquish the broader historical perspective and phlegmatic approach that is crucial to the reassertion of state power. Their goal must be to think strategically and avoid falling into the trap of reacting narrowly and directly to the violent initiatives taken by these groups.

That’s Audrey Kurth Cronin, Professor of Strategy at the U.S. National War College in her monograph, Ending Terrorism: Lessons for Defeating al-Qaeda.

But I want to turn to a critique leveled against my recent post, ”The Search for Answers in Fort Hood,” which discussed how little Fort Hood positions us to prevent similar incidents in the future. (I hope it was response and not reaction, but readers can judge for themselves.)

A thoughtful Cato colleague emailed me suggesting that there may have been enough indication in Nidal Hasan’s behavior—in particular, correspondence with Anwar al-Awlaki—to stop him before his shooting spree.

There may have been. Current reporting has it that his communications with al-Awlaki were picked up and examined, but because they were about a research paper that he was in fact writing, he was deemed not to merit any further investigation.

This can only be called error with the benefit of hindsight. And it tells us nothing about what might prevent a future attack, which was my subject.

If humans were inert objects, investigators could simply tweak the filter that caused this false negative to occur. They could not only investigate the people who contact known terrorists as they did Nidal Hassan, they could know to disregard claimed academic interests. Poof! The next Nidal Hassan would be thwarted at a small cost to actual researchers.

But future attacks are not like past attacks. Tweaking the filter to eliminate this source of false negatives would simply increase false positives without homing in on the next attacker. Terrorists and terrorist wannabes will change their behavior based on known and imagined measures to thwart them. Nobody’s going to be emailing this al-Awlaki guy for a while.

In “Effective Counterterrorism and the Limited Role of Predictive Data Mining,” IBM distinguished engineer Jeff Jonas and I used examples from medicine to illustrate the problem of false positives when searching for terrorism in large data sets, concluding:

The question is not simply one of medical ethics or Fourth Amendment law but one of resources. The expenditure of resources needed to investigate 3,000,000, 15,000,000, or 30,000,000 fellow citizens is not practical from a budgetary point of view, to say nothing of the risk that millions of innocent people would likely be under the microscope of progressively more invasive surveillance as they were added to suspect lists by successive data-mining operations.

The same problems exist here, where tens of thousands of leads may present themselves to investigators each year. They must balance the likelihood of harm coming to U.S. interests against the rights of U.S. citizens and the costs of investigating all these potential suspects.

Armchair terror warriors may criticize these conclusions a variety of ways, believing that post hoc outrage or limitless grants of money and power to government can produce investigative perfection. (n.b. Getting victim states to dissipate their own money and power is how terrorism does its work.) But none can accurately say based on currently available facts that anyone made an error. Much less can anyone say that we know any better how to prevent essentially random violent incidents like this in the future.