Now to explore another pair of common crime-drop explanations:

• Tougher gun laws

• Changes in crack and other drug markets

First, the guns. Debates on this subject are rarely coolheaded. Gun advocates believe that gun laws are too strict; opponents believe exactly the opposite. How can intelligent people view the world so differently? Because a gun raises a complex set of issues that change according to one factor: whose hand happens to be holding the gun.

It might be worthwhile to take a step back and ask a rudimentary question: what is a gun? It’s a tool that can be used to kill someone, of course, but more significantly, a gun is a great disrupter of the natural order.

A gun scrambles the outcome of any dispute. Let’s say that a tough guy and a not-so-tough guy exchange words in a bar, which leads to a fight. It’s pretty obvious to the not-so-tough guy that he’ll be beaten, so why bother fighting? The pecking order remains intact. But if the not-so-tough guy happens to have a gun, he stands a good chance of winning. In this scenario, the introduction of a gun may well lead to more violence.

Now instead of the tough guy and the not-so-tough guy, picture a high-school girl out for a nighttime stroll when she is suddenly set upon by a mugger. What if only the mugger is armed? What if only the girl is armed? What if both are armed? A gun opponent might argue that the gun has to be kept out of the mugger’s hands in the first place. A gun advocate might argue that the high-school girl needs to have a gun to disrupt what has become the natural order: it’s the bad guys that have the guns. (If the girl scares off the mugger, then the introduction of a gun in this case may lead to less violence.) Any mugger with even a little initiative is bound to be armed, for in a country like the United States, with a thriving black market in guns, anyone can get hold of one.

There are enough guns in the United States that if you gave one to every adult, you would run out of adults before you ran out of guns. Nearly two-thirds of U.S. homicides involve a gun, a far greater fraction than in other industrialized countries. Our homicide rate is also much higher than in those countries. It would therefore seem likely that our homicide rate is so high in part because guns are so easily available. Research indeed shows this to be true.

But guns are not the whole story. In Switzerland, every adult male is issued an assault rifle for militia duty and is allowed to keep the gun at home. On a per capita basis, Switzerland has more firearms than just about any other country, and yet it is one of the safest places in the world. In other words, guns do not cause crime. That said, the established U.S. methods of keeping guns away from the people who do cause crime are, at best, feeble. And since a gun—unlike a bag of cocaine or a car or a pair of pants—lasts pretty much forever, even turning off the spigot of new guns still leaves an ocean of available ones.

So bearing all this in mind, let’s consider a variety of recent gun initiatives to see the impact they may have had on crime in the 1990s.

The most famous gun-control law is the Brady Act, passed in 1993, which requires a criminal check and a waiting period before a person can purchase a handgun. This solution may have seemed appealing to politicians, but to an economist it doesn’t make much sense. Why? Because regulation of a legal market is bound to fail when a healthy black market exists for the same product. With guns so cheap and so easy to get, the standard criminal has no incentive to fill out a firearms application at his local gun shop and then wait a week. The Brady Act, accordingly, has proven to be practically impotent in lowering crime. (A study of imprisoned felons showed that even before the Brady Act, only about one-fifth of the criminals had bought their guns through a licensed dealer.) Various local gun-control laws have also failed. Washington, D.C., and Chicago both instituted handgun bans well before crime began to fall across the country in the 1990s, and yet those two cities were laggards, not leaders, in the national reduction in crime. One deterrent that has proven moderately effective is a stiff increase in prison time for anyone caught in possession of an illegal gun. But there is plenty of room for improvement. Not that this is likely, but if the death penalty were assessed to anyone carrying an illegal gun, and if the penalty were actually enforced, gun crimes would surely plunge.

Another staple of 1990s crime fighting—and of the evening news—was the gun buyback. You remember the image: a menacing, glistening heap of firearms surrounded by the mayor, the police chief, the neighborhood activists. It made for a nice photo op, but that’s about as meaningful as a gun buyback is. The guns that get turned in are generally heirlooms or junk. The payoff to the gun seller—usually $50 or $100, but in one California buyback, three free hours of psychotherapy—isn’t an adequate incentive for anyone who actually plans to use his gun. And the number of surrendered guns is no match for even the number of new guns simultaneously coming to market. Given the number of handguns in the United States and the number of homicides each year, the likelihood that a particular gun was used to kill someone that year is 1 in 10,000. The typical gun buyback program yields fewer than 1,000 guns—which translates into an expectation of less than one-tenth of one homicide per buyback. Not enough, that is, to make even a sliver of impact on the fall of crime.

Then there is an opposite argument—that we need more guns on the street, but in the hands of the right people (like the high-school girl above, instead of her mugger). The economist John R. Lott Jr. is the main champion of this idea. His calling card is the book More Guns, Less Crime, in which he argues that violent crime has decreased in areas where law-abiding citizens are allowed to carry concealed weapons. His theory might be surprising, but it is sensible. If a criminal thinks his potential victim may be armed, he may be deterred from committing the crime. Handgun opponents call Lott a pro-gun ideologue, and Lott let himself become a lightning rod for gun controversy. He exacerbated his trouble by creating a pseudonym, “Mary Rosh,” to defend his theory in online debates. Rosh, identifying herself as a former student of Lott’s, praised her teacher’s intellect, his evenhandedness, his charisma. “I have to say that he was the best professor that I ever had,” s/he wrote. “You wouldn’t know that he was a ‘right-wing’ ideologue from the class . . . There were a group of us students who would try to take any class that he taught. Lott finally had to tell us that it was best for us to try and take classes from other professors more to be exposed to other ways of teaching graduate material.” Then there was the troubling allegation that Lott actually invented some of the survey data that support his more-guns/less-crime theory. Regardless of whether the data were faked, Lott’s admittedly intriguing hypothesis doesn’t seem to be true. When other scholars have tried to replicate his results, they found that right-to-carry laws simply don’t bring down crime.

Consider the next crime-drop explanation: the bursting of the crack bubble. Crack cocaine was such a potent, addictive drug that a hugely profitable market had been created practically overnight. True, it was only the leaders of the crack gangs who were getting rich. But that only made the street-level dealers all the more desperate to advance. Many of them were willing to kill their rivals to do so, whether the rival belonged to the same gang or a different one. There were also gun battles over valuable drug-selling corners. The typical crack murder involved one crack dealer shooting another (or two of them, or three) and not, contrary to conventional wisdom, some bug-eyed crackhead shooting a shopkeeper over a few dollars. The result was a huge increase in violent crime. One study found that more than 25 percent of the homicides in New York City in 1988 were crack-related.