Some public-policy debates seem perpetual. And tragic, sensational events just last week may help explain why some disputes are so hard to settle, no matter how extensive evidence becomes on one side or the other.
Impassioned by the suffering involved in the social problems being debated, partisans on either side of stubborn policy quarrels often become deeply invested, personally and philosophically, in their predictions of what would follow if their misguided opponents' ideas were adopted. They quickly seize on evidence that appears to confirm their expectations, but find it challenging to see broader indications that their prediction may have been wrong.
Yet occasionally it happens that what social scientists call a "natural experiment" unfolds — often when one side in a long-running disagreement manages to enact its controversial policy prescription, at least in some jurisdictions. Over time, this allows us to test predictions — with data, not anecdotes — against reality.
Two notable natural experiments of this kind are in the news — one because its results seem increasingly clear, and the other because it is just getting underway.
The experiment whose results seem increasingly clear has been the coast-to-coast liberalizing of gun permit laws over the past several decades. An appalling on-air murder of a TV news crew in Virginia last week has of course reignited the broad debate over gun violence in America, as have so many shocking individual incidents before it. But the bigger picture, at least where carry permits are concerned, is less confounding and disturbing.
Only last Sunday, a front-page Star Tribune news story reported that 200,000 Minnesotans now hold legal permits to carry handguns — far more than were forecast by the most alarmed opponents of relaxed permit laws back in 2003, when the proposal to allow essentially any law-abiding adult to carry a handgun was enacted.
And yet, the paper reported, "Bureau of Criminal Apprehension data show that fatalities involving permit holders are rare," defying the fears of "opponents … that the law would lead to a surge in shootings and gun deaths."
Those fears were often vividly expressed. A Star Tribune editorial in 2003, citing a Brookings Institution study, warned that "when average citizens regularly have guns in pockets or purses … , '[o]therwise law-abiding people may become emboldened to do bad things, some of them violent.' "