In recent weeks there has been a lot of media coverage of a paper John Donohue and I recently wrote connecting the legalization of abortion in the 1970s to reduced crime in the 1990s. (A preliminary version of the paper is posted here.) The purpose of the study is to better understand the reasons for the sharp decline in crime during this decade, which, prior to our research, had largely eluded explanation. While there are many other theories as to why crime declined (more prisoners, better policing, the strong economy, the decline of crack, etc.), most experts agree that none of these very convincingly explains the 30 percent to 40 percent fall in crime since 1991.
The theoretical justification for our argument rests on two simple assumptions: 1) Legalized abortion leads to fewer "unwanted" babies being born, and 2) unwanted babies are more likely to suffer abuse and neglect and are therefore at an increased risk for criminal involvement later in life. The first assumption, that abortion reduces the number of unwanted children, is true virtually by definition. The second assumption, that unwanted children are at increased risk for criminal involvement, is supported by three decades of academic research. If one accepts these two assumptions, then a direct mechanism by which the legalization of abortion can reduce crime has been established. At that point, the question merely becomes: Is the magnitude of the impact large or small?
Our preliminary research suggests that the effect of abortion legalization is large. According to our estimates, as much as one-half of the remarkable decline in crime in the 1990s may be attributable to the legalization of abortion. We base our conclusions on four separate data analyses.
First, we demonstrate that crime rates began to fall 18 years after the landmark Supreme Court decision Roe vs. Wade legalized abortion across the nation, just the point at which babies born under legalized abortion would be reaching the peak adolescent crime years. In my opinion, this is the weakest of our four data analyses. In a simple time series, many factors are negatively correlated with crime. Furthermore, the world is a complicated place and it would be simplistic to believe that legalized abortion could overpower all other social determinants of crime.
Second, we show that the five states that legalized abortion in 1970--three years before Roe vs. Wade--saw crime begin to decrease roughly three years earlier than the rest of the nation. This is a bit more convincing to me but still far from conclusive.
Third, we demonstrate that states with high abortion rates in the mid-1970s have had much greater crime decreases in the 1990s than states that had low abortion rates in the 1970s. This relationship holds true even when we take into account changes in the size of prison populations, number of police, poverty rates, measures of the economy, changes in welfare generosity, and other changes in fertility. This is the evidence that really starts to be convincing, in my opinion.
Fourth, we show that the abortion-related drop in crime is occurring only for those who today are under the age of 25. This is exactly the age group we would expect to be affected by the legalization of abortion in the early 1970s. That is where our paper stops. Our paper is a descriptive exercise attempting to explain why crime fell. While our paper highlights one benefit of allowing women to determine whether or not to bring pregnancies to term, we make no attempt to systematically analyze the many possible costs and benefits of legalized abortion. Consequently, we can make no judgment as to whether legalized abortion is good or bad. In no way does our paper endorse abortion as a form of birth control. In no way does our paper suggest that the government should restrict any woman's right to bear children. Although these are the most interesting issues for the media to discuss, our paper actually has very little to say on such topics.
I think the crux of the misinterpretation of our study is that critics of our work fail to see the distinction between identifying a relationship between social phenomena and endorsing such a relationship. When a scientist presents evidence that global warming is occurring, it does not mean that he or she favors global warming, but merely that the scientist believes such a phenomenon exists. That is precisely our position with respect to the link between abortion and crime: We are not arguing that such a relationship is good or bad, merely that it appears to exist.
As an aside, it has been both fascinating and disturbing to me how the media have insisted on reporting this as a study about race, when race really is not an integral part of the story. The link between abortion and unwantedness, and also between unwantedness and later criminality, have been shown most clearly in Scandinavian data. Abortion rates among African-Americans are higher, but overall, far more abortions are done by whites. None of our analysis is race-based because the crime data by race is generally not deemed reliable.
I look forward to hearing your thoughts. I am interested in your views on the paper and its analysis, but also on the broader topic of the coverage of scientific research in the popular press, particularly when it relates to sensitive subjects like abortion, crime, or race. Do you think any good comes from a public discussion of academic studies such as this one? What, if anything, could be done to make such public debates more productive?