American gun policy is a deadly compromise.
Pro-gun advocates explain that the Virginia Tech killer would have been stopped in his tracks if students and teachers were carrying concealed weapons. This is absolutely correct -- it is obviously much harder to kill people who are armed.
Meanwhile, gun control advocates explain that those murders would never have happened if the killer could not get guns in the first place. The is also completely correct -- just look at the murder rate in Asia and Europe to see how limiting access to guns reduces violent crime.
Both sides are right, but they want to live in different worlds. The NRA crowd wants a society where everyone is walking around armed and vigilantly protecting their own security. The gun control crowd wants a world where people are safe without packing heat and doing weekend target practice.
Most people don't want to live in the world the NRA is envisioning, but enough Americans do that it is politically impossible to drastically restrict gun ownership. That means we will have the same argument after each public tragedy and both sides of the debate will be perpetually right. But being right does not solve the problem, it just leaves us stuck with the deadly compromise.