I suspect that both the readers who have stuck it out with us this far and the professors at Harvard, Stanford, and the University of Chicago who heard you present your theory must be thinking roughly along these lines: "Well, I'm not sure I followed all the statistical details, but Professor Levitt's basic point is pure common sense. As long as abortion rids us of more fetuses likely to become gang members, it simply must reduce crime." That would explain why those high-powered academics forgot to point out to you that, contra your theory, when the first generation to "benefit" from being culled by legal abortion reached ages 14 to 17, they went on a homicidal rampage. (Click here to see FBI graph.)
Therefore, rather than mud wrestle in the numbers here, I'll privately send you my technical suggestions. In this essay, I'll step back and explain why this straightforward insight might not actually work in practice.
The widespread assumption that your theory must be correct reveals just how many people deep down believe, whether they admit it publicly or not, that "certain people" are just permanently more incorrigible than others. As a contender for the World's Least Politically Correct Human, I'm sympathetic. It's ironic, but because I've been arguing for years that genetic diversity affects society, I was one of the few to notice in this particular case that crime has risen and fallen not because we are aborting the poor and black and unwanted, but because of that staple of genteel liberal commentary, Cultural Forces (e.g., crack).
Your "differential fertility" logic has a fascinating history. That the poor outbreed the rich was noted at least as long ago as Adam Smith's The Wealth of Nations. A long line of both conservative and progressive nail-biters have worried that a bourgeoisie that's self-disciplined and responsible enough to use abstinence or contraception will someday be demographically swamped by a working class too sexually indulgent and disorganized to prevent pregnancies. The "eugenicists" feared the spread of the lower orders' inadequate genes, while the "euculturalists" dreaded their cruder culture. And agnostics on the subject realized that while disentangling nature and nurture was extremely difficult (only with the advent of twin and adoption studies have we made much progress), the precise mechanism mattered surprisingly little. Whether from genes or upbringing or both, people who are too irresponsible or incompetent to prevent most unwanted pregnancies tend to have fairly irresponsible or incompetent children. Thus, many unreligious right-wingers and WASP progressives (e.g., Margaret Sanger, founder of Planned Parenthood) supported abortion as the antidote to the bad demographic effects of contraception. Abortion would allow the working class to tidy up its mistakes.
This logic implies that legalized abortion should reduce illegitimacy. And since illegitimacy is closely linked to crime, therefore abortion must reduce crime. Right? Yet, abortion and illegitimacy both soared during the '70s, and then the youth violent-crime rate also soared when the kids born during that decade hit their teens. How come?
In theory, legal abortion reduces murder by being, in effect, "prenatal capital punishment." But, first, it's not very efficient. Like Herod, we have to eradicate many to get the one we want. While genes and upbringing do affect criminality, there's so much randomness that predicting the destiny of individual fetuses is hard.
Second, what if besides a contraceptive-using bourgeoisie and an abortion-using working class, there also exists an underclass to whom, in the words of Homer Simpson, "Life is just a bunch of things that happen"? What if in the '70s members of the underclass didn't effectively use either contraception or abortion, but, being too destitute or distracted or drunk or drugged, they just tended to let shit happen all the way to the maternity ward? And what if the legalization of abortion gave them an excuse to be even less careful about avoiding pregnancy? In fact, in your paper you cite evidence that 60 percent to 75 percent of all fetuses aborted in the '70s would never have been conceived without legal abortion. If that's what happened across all classes, the increase in careless pregnancies specifically among the underclass might have been so big that it negated the eugenic or euculturalist effects of abortion.
Thus, legalizing abortion would have thinned the ranks of the respectable black working class but not the black underclass. Its cultural influence would therefore have mounted. Just compare the working-class black music of the '60s (e.g., Motown) with the underclass gangsta rap of the late '80s, which spread the lethal bust-a-cap code of the East Coast and West Coast crack dealers across America.
Third, legalizing abortion finished off the traditional shotgun wedding. Earlier, the pill had shifted responsibility for not getting pregnant to the woman. Then, legal abortion relieved the impregnating boyfriend of the moral duty of making an honest woman out of her. This would drive up the illegitimacy rate.
Finally, even more speculatively, but also more frighteningly, the revolution in social attitudes that excused terminating the unborn may also have helped persuade violent youths that they could be excused for terminating the born.
To conclude, you ask for my prediction on crime trends. Because you failed to use data that focused precisely enough on particular generations (e.g., the highly violent group born after Roe vs. Wade in 1975-1979), your model has consistently failed to even predict the past. For example, in utter contrast to your logic, the murder rate for 14- to 17-year-olds even in the low crime year of 1997 was 94 percent higher than it was for 14- to 17-year-olds in 1984. Yet, over the same span, the murder rate for 25- to 34-year-olds (born pre-legalization) has dropped 27 percent. (Click here to see FBI table.)
Thus my faith in your theory's ability to forecast the future is limited. Last week, in the Human Biodiversity discussion group, the polymath Gregory Cochran (who was the co-subject of the February 1999 Atlantic cover story on his new Darwinian theory of disease) responded to your prediction that crime will fall slowly for another 10 to 15 years, assuming all else is equal: "A counter-prediction: that all else will not be equal. Social changes are more important to crime trends than abortion, they're still ongoing, and they're likely to dominate." At some point in the future when black teens no longer remember much about the previous generation's self-inflicted crack wound, somebody will invent a new drug. Then we'll be back on another drug-epidemic-driven crime roller coaster.