This is that the most important force behind elective lone parenthood is not ' feckless' men, but the attitude of women and girls.
In the past ... men committed themselves to the mothers of their children on the basis that they could trust they were indeed the father because the woman was sexually faithful. Today, this bargain has been all but destroyed.
This has given rise to an increasing number of women-only households where fathers have been written out of the family script for three or four generations or more. The consequences of such family disintegration - as is now indisputable - are in general catastrophic for both individuals and for society.
This problem will not be cracked, however, unless women come to believe once again that their interests lie in attracting one man to father their children and then stick with them.
In a meeting last week of the Centre for Policy Studies to discuss Dench's research, it was suggested that the state should pay a dowry to couples who undertook to stay together, and that this dowry should be paid to the girl in such a relationship.
It seemed to me, though, that girls already have a kind of dowry in the form of Child Benefit, paid to mothers on the birth of every child - a dowry with a destructive effect. For the great unsayable is that Child Benefit acts as a huge incentive to have children outside marriage.
But the greatest need children have is for their two parents to bring them up.
And what few anticipated was that, along with the impact of all the other social and economic changes, some women used Child Benefit to help junk men altogether as superfluous to requirements.
Marriage has always helped turn young men into responsible adults.
What's needed, therefore, is to help turn men once again into an attractive, marriageable proposition.
The most important thing they need is, of course, a job - which is why the policy of pushing lone mothers out to work is actually disastrous, particularly in areas of high unemployment.
But welfare must stop reinforcing the idea that men are dispensable. The best way of underpinning marriage is probably through transferable tax allowances for married couples.
The undoubted expense of such measures would be more than offset by reducing the astronomical cost to this country of family breakdown.
The irony is that, as a result of modern notions of gender equality, it is men who now need special help to restore the sexual bargain that will not just benefit the male sex but stop the degradation of women and family life that so threatens us all.In Canada and America, this economic transfer has occurred without massive state intervention so common in England and other "so-called" Liberal Social Democracy's merely by imposing most of that burden directly onto fathers - along with not bothering to concern themselves about how men survive their ever increased financial burden. Meanwhile we have the Gold-Diggers Sweepstakes. Whoever can trap a man into sex can shortly afterwards decide to have a child and go after whatever wealth he has accumulated by being sexually cautious.