As a professor, I’d feel safer if guns were not permitted on campus. I worry more about being the target of a student upset about failing grades than about a mass killer roaming the hallways.

But there is little evidence to support my gut feeling. Utah, for example, has not seen an increase in campus gun violence since it changed its law in 2006. And a disturbed student can simply sneak a gun on campus in his backpack, as the Virginia Tech killer did in 2007. Indeed, lost in the debate is the fact that guns, being easy to conceal, are almost certainly on campus already.

On the other hand, gun rights advocates are too quick to assume that laws allowing guns on campus will discourage mass murderers. Arizona has among the most liberal gun-carrying laws in the nation, but that didn’t prevent Jared L. Loughner from shooting Representative Gabrielle Giffords and killing six other people in Tucson in January. Nor did permissive carry laws lead to people defending themselves by shooting back. (Mr. Loughner was tackled and brought to the ground by unarmed bystanders.)

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Even if a student with a gun can use it to defend against a mass murderer, it’s hardly clear that anyone, including the armed student, is made safer. Policemen or other students with guns might not be able to differentiate among gunmen, putting the person defending herself at risk of being shot by mistake. Even well-trained gun owners suffer enormous mental stress in a shootout, making hitting a target extremely difficult.

Gun control groups are fighting to retain the bans. This is one of the few areas in which they’ve had success in recent years. There have been more than 40 attempts to lift the bans in 24 states, and nearly all have failed. Even the proposed Arizona law was a victory of sorts, as the final bill omitted provisions allowing guns in classrooms; it would permit guns only on campus streets and sidewalks.

Yet gun rights proponents are redoubling their repeal efforts. They aren’t reacting to a wave of violence on campus. The true motivation is to remove the stigma attached to guns. Many in the gun rights movement believe there should be no gun-free zones and seek to make the public possession of firearms a matter of course. The protesters who last year carried guns into Starbucks shops and Tea Party rallies had the same goal. They weren’t expecting to defend themselves; they were aiming to build broader public acceptance of guns.

Exposure can breed tolerance. Arguably, that is exactly what’s behind the growing acceptance of gays and lesbians. The visibility of gay couples in society and popular culture has led many Americans to realize that homosexuality is not wrong. Gun advocates are betting the same can happen with firearms.

The strategy, however, is risky. Teenagers might begin to see carrying a gun as a mark of adulthood, like smoking and drinking. Without the maturity of age, they might turn to violence too quickly.

Gun rights advocates are willing to take these risks because colleges are where the next generation of America’s leaders will be produced. What better place to affect people’s attitudes about guns than the very institutions responsible for teaching our most cherished values and ideals?