By Monday, Gov. Jan Brewer of Arizona must decide whether to sign a bill partly lifting her state's ban on guns on college and university campuses. Gun advocates insist that will make campuses safer by discouraging mass killers and giving students the ability to fight back. Gun control proponents warn the law will lead to more lethal violence. Both sides are probably wrong. Gun violence at colleges and universities — there are fewer than 20 homicides on campus per... (GunPolicy.org)