I know that current pro-gun fanatics, who are almost exclusively right-wingers, will hate to be called "gun liberals", but that is what they are advocating when they argue that there should be less restrictions on owning or carrying firearms. I know that, to them, liberal just means something derogatory, but to those who know the meaning of words, the term "liberalize" means to be make less restrictive, and this is what they are advocating. On the other hand, "gun conservatives" (gunservatives), who happen to be primarily left-wingers in the US, are those who want to tighten regulations on gun ownership and carrying. I'm sure that this kind of "semantic" argument would drive a person like Jared Loughner even crazier than he already must have been.
That brings me to the common sense, centrist issue of the day. Any person with common sense would agree that a crazy person should not be carrying around a gun with a high capacity magazine. Yet, according to gun fanatics, no regulations can be placed on gun ownership. Their argument that gun regulation is unconstitutional relies upon reading only the second half of the Second Amendment to the US Constitution, and purposely omitting the part that says, "a well REGULATED militia being necessary to the security of a free State,". Instead they only cite, "... the right of the people to keep and bear Arms, shall not be infringed."
Therefore, it is an inescapable consequence of their pro-gun position that crazy people should be allowed to carry guns. One wonders how "pro-life" the "pro-gun" position is, in this case, since crazy people, by definition, are not going to make sane choices about the use of lethal force.
That is, even if everyone else is armed and is able to kill the crazy person after he or she starts shooting, then at least one person, but probably more than one, will be dead. Granted, it will be self-defense to shoot the crazy person, but allowing that crazy person to have the gun in the first place, knowing that they are mentally incapable of acting responsible, is the reason that multiple lives end up endangered or destroyed. Even if these people just use the gun to kill themselves, making this easy option available to them makes it easier than it has to be to carry out their reckless plans.
Now, I know that a favorite "argument" is that "criminals will break the law". However, in the case of people with diminished mental capacity, we should still be trying to make it as hard as possible for them to carry out their plans. If they are forced to turn to improvised weapons like knives, then the body count will likely be far diminished. Allowing them the convenience of purchasing an "off-the-shelf" professionally-designed "massacre machine" from Walmart should not be an option open to them.
Gun fanatics also like to play the "personal responsibility" card, but the fact is that crazy people are not capable of personal responsibility, by their nature. More importantly, craziness sometimes develops slowly, and can be hard to detect. Often times crazy people don't even know it, or are in denial about it. So I highly doubt that people who are beginning to experience episodes of mental instability are going to say, "Golly gee, I guess I should trot down to the police station and turn in my firearms so that I don't accidentally hurt someone with them".
Now the fact is that there are gun fanatics out there, but the real people who benefit from all this divisive rhetoric are the gun manufacturers. They want to sell as many guns as possible, and requiring a person to undergo a psychological evaluation before being able to buy a gun would reduce sales. Even having to put safety devices on guns makes them more expensive, which again can cut into sales. Gun manufacturers don't want to have any regulations, because it could hurt the bottom line, so they strongly sponsor the pro-gun activism and the abolition of regulations.
So what can common sense centrists do. For one thing, we have to break out of the traditional roles. Liberals have not fared well on the gun-control debate. All the money comes from the gun manufacturers and goes straight to the coffers of groups that advocate gun fanaticism. Money is life-blood in politics. Therefore, for a policy to be successful, it must not cut into sales. I believe that liberals could appeal to gun manufacturers with a policy that says, "we will encourage more liberals to purchase guns and safety locks and concealed permits". This represents a new revenue stream for gun makers, if political leaders on the left can convince their constituents that responsible gun ownership can help make themselves and their community safer.
On the right-wing, perhaps one can appeal to a need for security. We don't want terrorists, for example, many of whom are not always mentally stable either, to have easy access to firearms. Therefore, requiring customers to complete a mandatory psychological evaluation, and periodic evaluations, would probably weed out a few people who shouldn't have a firearm. I know that right-wingers are paranoid about people "trying to take my gun", but if police did come around occasionally confiscating guns from people with lapsed permits this would only create more sales, or at least encourage people to more diligent about keeping the permit current, and paying their fees.
It would also potentially win a new revenue stream from mental health practitioners. They would likely be glad for the extra business, and would throw contributions to whatever politician pushed this kind of agenda. The trick is to balance this with not pissing off the gun makers, by promising to help them get customers who from new demographics, like liberals, and middle-of-the-road people who aren't as paranoid as the average person to which they currently market.