This works out fine, except when one compelling idea contradicts another. Then I'm at a bit of a loss. Take, for example, the various explanations for the dropping crime rate in NYC.
From 1987 to 1994, NYC had over 2000 murders every year, with a high of 2,605 in 1990. In 1995 it began dropping. In '98, it dipped below 1000 for the first time in 41 years, and has stayed there ever since. In 2007, it's on a pace to dip under 500. (The population has remained somewhat static throughout this entire period, from 17m to 19m).
There were many theories explaning this huge drop. The end of the crack epidemic. Tougher jail sentences. More police on the street. Better policing techniques. Then, in 2000, Malcolm Gladwell published a book called The Tipping Point. There are many fascinating case studies in this book, but in one he credits the drop in crime to new police techniques installed by Mayor Rudy Giuliani and Police Commissioner William Bratton, techniques built on the Broken Windows theory.
This theory was developed by James Q. Wilson and George L. Kelling in an article called "Broken Windows: The Police and Neighbour Safety". Here are the authors:
"Social psychologists and police officers tend to agree that if a window in a building is broken and is left unrepaired, all the rest of the windows will soon be broken. This is as true in nice neighborhoods as in run-down ones. Window breaking does not necessarily occur on a large scale because some areas are inhabited by determined window-breakers whereas others are populated by window-lovers; rather, one unrepaired broken window is a signal that no one cares, and so breaking more windows costs nothing (it has always been fun)."
In other words, if you allow bad behavior to happen, it encourages more bad behavior. And theoretically, if a police force cracks down on small crimes,it will create an environment that reduces large crimes. The NYPD began cracking down on fare-jumpers and squegee men, and the overall crime rate began to plummet. What a fascinating idea. I'm sold!
The Roe Effect
There was one problem with this theory...except for a few hard cases like DC and Detroit, violent crime was dropping everywhere, not just New York. So along comes Steven Levitt, an economist from the U. of Chicago, with his book Freakonomics: A Rogue Economist Explores the Hidden Side of Everything. In this book, Levitt and his co-author use the tools of economics to answer some interesting, non-economics questions, like: Are guns more dangerous than swimming pools? Why do drug dealers live with their Moms?
And...how did the legalization of abortion help reduce the rate of violent crime? The essay in the book is based on a scholarly paper Levitt co-wrote in 2001 with John Donahue from Yale Law School, entitled "The Impact of Legalized Abortion on Crime". Here is what they write in the abstract of that paper:
"We offer evidence that legalized abortion has contributed significantly to recent crime reductions. Crime began to fall roughly 18 years after abortion legalization. The 5 states that allowed abortion in 1970 experienced declines earlier than the rest of the nation, which legalized in 1973 with Roe v. Wade. States with high abortion rates in the 1970s and 1980s experienced greater crime reductions in the 1990s. In high abortion states, only arrests of those born after abortion legalization fall relative to low abortion states. Legalized abortion appears to account for as much as 50 percent of the recent drop in crime."
Levitt's controversial thesis, which he supports with massive demographic evidence, is that unwanted children are more likely to commit a violent crime later in life. Since these unwanted children weren't born, they didn't grow up to become criminals.
It's a dangerous idea, but it's difficult to read Levitt's argument and the evidence he marshalls and not find the data persuasive. And, idea slut that I am, I was persuaded.
But not everyone was sold. Levitt, naturally, was attacked by the Left and the Right for proposing such a controversial theory. Many of the criticisms challenged Levitt's statistics about crime and abortions, and Levitt even made some minor changes to his original research. But I found one counter-argument particularly intriguing.
The conservative economist John Mueller wrote a negative review of Freakonomics based on the idea of economic fatherhood (meaning: being financially responsible for a child). He argues that Roe v. Wade didn't lead to a drop in crime in the 90's...it led to an increase of crime in the 70's and 80's: Here is Mueller:
"As far back as data exist, rates of economic fatherhood and homicide have been strongly, inversely "cointegrated"—a stringent statistical test characterizing inherently related events, like the number of cars entering and leaving the Lincoln Tunnel. Legalizing abortion didn't lower homicide rates 15-20 years later by eliminating infants who might, if they survived, have become murderers: it raised the homicide rate almost at once by turning their fathers back into men without dependent children—a small but steady share of whom do murder."
Well, shoot, that's kind of compelling, too, ain't it?
So where does that leave me? First of all, I should say that part of the reason I'm swayed is that I don't let my personal opinions affect my ability to judge the merits of an argument. Abortion is an issue that people hold such strong views that, naturally, they read the latter two arguments through the prism of those views. I am able to judge the merits of those arguments without prejudice.
On the other hand, I'm at a bit of a loss to explain why crime dropped so radically in the 90's.
So, I'm working on my own idea, the Baywatch Theory, that demonstrates a precise inverse correlation between the drop in crime from 1991 to 2001 with the popularity of the most watched television show of all time.
Coincidence? I don't think so...