Last year Virginia legislators considered a bill that would have overridden policies at public universities that prohibit students and faculty members with concealed handgun permits from bringing their weapons onto campus. After the bill died in committee, The Roanoke Times reported, Virginia Tech spokesman Larry Hincker welcomed its defeat, saying, "I'm sure the university community is appreciative of the General Assembly's actions because this will help parents, students, faculty and visitors feel safe on our campus."

Maybe Hincker was right. But as Monday's horrifying mass murder at Virginia Tech vividly demonstrated, there is a difference between feeling safe and being safe. The university's gun ban not only did nothing to protect people at the school; it left them defenseless as a cold-blooded gunman methodically killed 32 of them over the course of two and a half hours.

If some students and faculty members had access to guns during the attack, there's a good chance they could have cut it short. According to witnesses, the killer -- identified by police as Cho Seung-Hui, a senior studying English -- took his time and paused repeatedly for a minute or so to reload.

In shootings at other schools, armed students or employees have restrained gunmen, possibly preventing additional murders. Four years ago at Appalachian Law School in Grundy, Va., a man who had killed the dean, a professor and a student was subdued by two students who ran to their cars and grabbed their guns. In 1997 an assistant principal at a public high school in Pearl, Miss., likewise retrieved a handgun from his car and used it to apprehend a student who had killed three people.

Not only can guns in the hands of law-abiding citizens save lives in situations like these; they may even make such situations less likely. It may seem implausible that the possibility of armed victims would deter a seemingly irrational, suicidal attacker such as Cho, who ended his attack by shooting himself in the head. But even a gunman who expects to die during an attack does not want to be stopped before he can carry out his homicidal mission.

In a 1999 paper, economists John Lott and William Landes presented evidence that such concerns do in fact deter attacks. Looking at public shootings with multiple victims between 1977 and 1995, Lott and Landes found they were substantially less common in states where law-abiding residents are allowed to carry handguns after meeting specified requirements, such as a background check and firearms training.

This difference remained even after Lott and Landes controlled for a variety of variables, such as population, poverty and arrest rates, that might be expected to affect violent crime. They also found that attacks in states with relatively liberal carry permit policies tended to be less lethal, presumably because they are more often stopped by armed bystanders.

In addition to illustrating the folly of gun-free zones, the Virginia Tech massacre shows the pointlessness of laws aimed at firearms that are said to be especially dangerous or especially useful to criminals. Paul Helmke, president of the Brady Campaign to Prevent Gun Violence, responded to the Virginia Tech shootings by bemoaning "how easy it is for an individual to get powerful weapons in our country."

Cho used two handguns, a .22 and a 9mm, neither of them especially powerful or exotic. Contrary to the false promises of gun controllers, firearms cannot be neatly sorted into "good" and "evil" categories; any weapon that can be used for self-defense (or for hunting) also can be used to murder people. A gun's specific features matter even less if the victims are unarmed.

"We can't have an armed guard in front of every classroom every day of the year," Virginia Tech campus police chief Wendell Flinchum said after the shootings. Given the reality that police cannot be everywhere, it is unconscionable to disarm people who want to defend themselves.