Allan Carlson concludes Conjugal America with a call for governmental "family policy." But he really doesn't want to. He wishes the government would leave the family alone. Since the Enlightenment, though, and especially since the New Deal, the reach of the government is so extensive that it is unrealistic to think the family and the state could leave one another alone. Better, then, to join them than to fight them.
Carlson wants family policy to recognize that the main social purpose of marriage is procreation, not pleasure. The government's main purpose in family policy, therefore, should be to support procreative marriage and to support married parents in raising their children. Everything else is secondary. The state will need to help support children when their parents can't – or at least it should support other institutions that step in the help the kids. And marriage, as a name and legal status, should be preserved for one man/one woman couples, because they could be procreative.
Does Carlson's position rule out homosexual marriage? Yes. Does it rule out homosexual civil unions? Probably not. By the same token, couples that have kids should not be supported by the state as if they were married; instead, they should be encouraged to just go ahead and get married. And any policies which create perverse incentives for parents not to get married should be eliminated.
Carlson has a reputation in liberal circles as a way-out-there conservative. The position that argues for in Conjugal America, though, is actually pretty centrist. It is also quite close to what most Americans seem to support, based on opinion polls and recent votes on marriage amendments. Marriage is for kids. Other relationships can be good enough. But the state should not treat them as the same as marriage, nor is it obliged to consider them just as good for raising kids.