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In debates on gun control, gun opponents usually speculate about what might go wrong. Unfortunately, the current debate over arming soldiers on military bases is no different.

Except for the military police, soldiers on military bases are banned from carrying guns. But that hasn’t always been the case.

The ban itself hasn’t been around that long. It was proposed during the George H.W. Bush administration in 1992 as an effort to make the military a more "professional business-like environment." President Clinton rewrote and implemented the ban in 1993.

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After the attack at Fort Hood this past week, many soldiers no doubt wished they had been carrying a gun. The six minutes before military police arrived at the scene proved much too long for the three people killed and 16 wounded.

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Soldiers who survived the 2009 attack at Fort Hood, Staff Sgt. Shawn Manning, Sgt. Howard Ray and retired Sgt. Alonzo Lunsford, warn it is time the 1993 rule be revised.

Master Sgt. C.J. Grisham points out that there have been “nearly two dozen shootings at U.S. military installations” since the 1993 ban. Yet such attacks have not occurred in Iraq and Afghanistan, where virtually all soldiers have carried a loaded weapon. Nor were they occurring when guns were allowed to be carried on U.S. bases. Gun-free zones in the military have not worked any better than they have in civilian life.

On Sunday, CBS's Bob Schieffer asked White House Senior Adviser Dan Pfeiffer whether the Obama administration was "considering the idea of arming some of the soldiers that are on these bases." Pfeiffer's response: "They don't think it's a good idea."

When Schieffer asked why, Pfeiffer didn’t have an explanation: “We have to do a lot more to ensure that our men and women feel safe.”

Despite all the focus on mental illness, as last week's attack at Fort Hood shows, it is exceedingly difficult to predict who will become a mass murderer. The Army psychiatrist who last saw the Fort Hood killer found no “sign of likely violence, either to himself or to others.”

Similarly, the killers at Sandy Hook Elementary School and the Aurora, Colo., movie theater had also seen psychiatrists. Yet no one thought that they posed sufficient danger to themselves or others until it was too late.

On Tuesday the Washington Post probably gave the clearest explanation for why some people oppose arming soldiers: "Base commanders should not want to make it easier for escalating fights to turn deadly. Another [reason] is that even well-meaning people can miss with a shot or accidentally discharge a weapon."

But these concerns are just hypothetical possibilities. In reality, soldiers have been trusted at bases in Iraq and Afghanistan without such shooting incidents. No acknowledgment that allowing lots of good people to defend themselves can dissuade the few bad ones from harming others.

The Washington Post approvingly cites the Heritage Foundation’s Steve Bucci, a former commander of the U.S. Army’s 3rd Battalion who worries: “even in the military there’s varying levels of training and capability at using weapons.”

The fears about soldiers being armed have also been repeatedly voiced for civilian concealed handgun permit holders. Yet many mass public shootings have been stopped by permit holders. Look at some of the cases: Shootings at schools were stopped before police arrived in such places as Pearl, Miss., and Edinboro, Pa., and at colleges like the Appalachian Law School in Virginia. Or consider attacks in busy downtowns such as Memphis; churches such as the New Life Church in Colorado Springs; malls in Portland, Ore., and Salt Lake City; or outside an apartment building in Oklahoma.

With far less training than our soldiers, none of these permit holders has ever accidentally shot a bystander. None of these civilians has been accidentally shot by police who arrive on the scene.

Of course, just as in civilian life, not everyone on a military base needs to be armed. Killers need only realize that some soldiers will be able to respond quickly.

On Friday on MSNBC, retired Col. Jack Jacobs worried: “You are not going to be able to deter someone who is absolutely hell-bent on doing damage.” But absolute deterrence isn’t the relevant standard. We can still discourage many attacks, and we can reduce the carnage for the attacks that still take place.

And compared to hiring a lot more military police, arming soldiers is a relatively cheap way of accomplishing this deterrence.

Too much is at stake over safety to debate policy without looking at the data.