(FORTUNE Magazine) – The op-ed pages tell us the country has another ''crisis'' on its hands, and this one looks entirely real. It is the explosion of births to unmarried white mothers. In the 1970s some 6% of white births were illegitimate. In 1991 it was 22%. Testifying recently before Pat Moynihan's Senate Finance Committee, sociologist Lee Rainwater of Harvard noted that current growth rates imply a stunning 40% by 2000. The breakdown of the black family is a more familiar story. Two-thirds of black births are now to single women. Black illegitimacy -- first identified as a major social problem by Moynihan 30 years ago, when the rate was about 25% -- has depressed black living standards and magnified black crime rates. Fatherless families overproduce delinquent kids; heavy concentrations of such families create an underclass. The prospect now being pointed up by Charles Murray, on the Wall Street Journal's op-ed page, is for an emerging white underclass in America. Murray makes it clear that despite Murphy Brown and Mia Farrow, the phenomenon is still centered on poor and less educated whites. Where did this disaster come from? Welfare's perverse incentives have plainly played a role for whites as well as blacks. But we cannot down a thought about another source of the problem: modern feminism. Feminism means a lot of different things these days, but one proposition associated with the movement has always been utterly clear: It rejects the idea that women must be ''cared for'' by men. And a corollary: that marriage is central to women's lives. So today millions of women have ''relationships'' and observe that the men in their lives don't want ''commitments.'' Which all seems unremarkable. Sex without family responsibilities looks like a sweet deal to a lot of men. Until now, it never occurred to them that they could get this deal so easily -- or that ''family values'' would be a slogan derided by feminists.