It's tempting, after a hideous event like the shooting in Tucson, to want to "do something" about gun violence. But let's pause to consider what that something could be, and what price we might pay for doing it.

Much has been made of Arizona's notoriously lax gun laws. But Arizona law was irrelevant to Jared Loughner's purchasing the gun. The background check is federal, and he passed it. Yes, his carrying concealed to the Safeway, without a permit, was legal under Arizona's new law, but if it hadn't been, would he have been dissuaded? He headed off to commit murder; he was already far over the line where a concealed-carry law would have made any difference to him.

As a liberal Democrat, I worry about the damage we might do by rushing toward a fresh raft of gun-control laws. It's very hard to demonstrate that most of them -- registration, waiting periods, one-gun-a-month laws, closing the gun-show loophole, large-capacity-magazine restrictions, assault-rifle bans -- have ever saved a life. It's a hard thing to accept, but in a country of 350 million privately owned guns, the people who are inclined to do bad things with guns will always be able to get them. One might as well combat air crashes by repealing gravity.

I'm not one for slinging statistics, because everybody can read into them what he wants to see. One, though, seems pretty hard to ignore: The rates of murder and other violent crime have dropped by about half in the past 20 years -- one piece of unalloyed good news out of the past two decades. During those same 20 years, gun ownership has gone way up, and gun laws have become far looser.

Gun guys are convinced there's a causal relationship -- they say that criminals become timid in the face of an armed citizenry. I think the crime drop has more to do with changing demographics and smarter policing. Either way, it is obvious that more guns and looser gun laws did not cause crime to rise. We on the left, who have an impulse toward ever tighter gun laws, need to look squarely at that. If what we want to do is reduce violent crime, perhaps we should continue what we're doing. While it may be true that nothing can be done to keep guns out of the wrong hands, it is plainly false that nothing can be done to reduce violence. Lots is being done, and quite successfully. It just doesn't involve restricting guns.

Gun control not only does no practical good, it actively causes harm. It may be hard to show that it saves lives, but it's easy to demonstrate that we've sacrificed a generation of progress on things like health care, women's rights, immigration reform, income fairness, and climate change because we keep messing with people's guns. I am researching a book on Americans' relationship to their guns, and keep meeting working-stiff gun guys -- people whose wages haven't risen since 1978 and should be natural Democrats -- who won't even listen to the blue team because they're convinced Democrats want to take away their guns. Misguided? Maybe. But that's democracy for you. It's helpful to think of gun control as akin to marijuana prohibition -- useless for almost everything except turning otherwise law-abiding people into criminals and fomenting cynicism and resentment. All the talk of a new large-magazine ban hits gun guys' ears like liberals using this disaster to trim back gun rights a little. It reinforces the toxic narrative that the Democrats are the enemy of regular guys, which is the last thing we need right now.

If, say, a ban on large-capacity magazines would actually do some good -- i.e. save some lives -- we could argue about whether it's worth taking some heat from the gun guys over it. But politics is a cost-benefit analysis -- what are you going to get vs. what you're going to lose. In this case, progressives have a tremendous amount to lose, and almost nothing to gain. As a nation, we have a lot of work to do on many fronts, and all of it is going to require cooperation. Let's not make the job harder, in our hour of grief, by blindly running toward new gun-control "solutions" that will do little if anything to prevent further tragedies.