What about harsh punishment? Statistics from MIT psychologist Stephen Pinker's new book on global trends in violence show the United States used to execute more than 100 times the amount of people in the 1600s as it does today -- and yet violence rates then were far higher than today. Think Clint Eastwood's western, The Good, the Bad and the Ugly: Despite all of the authorized hangings, there was still a lot of unofficial shooting. More broadly, the number of countries using the death penalty has declined worldwide -- along with violent crime rates.
In a survey asking "What Do Economists Know About Crime" for the National Bureau of Economic Research (NBER), Angela Dills, Jeffrey Miron, and Garrett Summers conclude "economists know little." They suggest that it isn't just incarceration or the death penalty -- any link between lower crime and the number of police, higher arrest rates, and the stock of guns (whether more or less of them) is weak. Studies from Latin America have echoed that longer sentences are not linked to lower crime rates -- although a higher probability of being caught may be related to less violence in the region.
At the same time, for those convinced that crime is a product of poverty and inequality, the recent trends for New York and the nation as a whole also pose a challenge: For all the growing estates of the plutocrats in Wall Street, neither growing inequality nor rising unemployment has reversed the downward path of crime. Similarly, Latin American evidence suggests that while rising inequality might be linked to increased violence in the region, average incomes are not -- richer countries are no safer than poorer ones, all else equal.
What about drugs, then? Interestingly, the NBER survey notes that drug enforcement might increase crime. The authors suggest that "If government forces a market underground, participants substitute violence for other dispute-resolution mechanisms," -- i.e., if they can't go to court to settle their dispute over who gets which street corner, rival drug gangs will shoot each other instead.
New York's experience suggests that it is possible to reduce the violence associated with drugs by taking those disputes off of the street. Franklin Zimring, a law professor at the University of California, Berkeley, suggests that one important factor behind the decline in homicide in New York was shutting down open-air drug markets. It didn't slow sales, but it did eliminate 90 percent of drug-related killings over turf conflicts. Echoing the recent pattern in New York City, Eisner suggests that the long-term historical decline in Western homicide rates as a whole is associated with "a drop in male-to-male conflicts in public space."
Over the sweep of centuries, Eisner suggests that cultural change -- from "knightly warrior societies" to "pacified court societies" -- is an important factor. So are we just getting more civilized, then? Indeed, the decline in violence coincides with global evidence of converging attitudes towards greater toleration. For example, the proportion of people worldwide who say they wouldn't want to have a neighbor of a different religion dropped from 67 percent to 48 percent between the early 1990s and the mid-2000s. Turn on the television and you'd be sure to think that political dialogue is getting more rancid by day. And it might be, but people's attitudes are actually becoming more pacific and tolerant.