Jim DeMint, former senator and future president of the Heritage Foundation, writes a column for USA Today opposing gay marriage. But like so many social conservatives, he supports his position with a sleight of hand. DeMint writes:

Without strong families grounded in marriage, we cannot hold back the ever-expanding power of government. As the marriage culture weakens, Big Government grows. Just look how the welfare state has expanded as the unwed childbearing rate has grown from single digits in the 1960s to more than 40% today.

Marriage policy exists to encourage a man and a woman to commit to each other permanently and exclusively as husband and wife and to be father and mother to any children. Sound marriage policy strengthens civil society and reduces the role of government.

The erosion of marriage costs taxpayers. And it’s not just conservatives who say this. Even the left-leaning think tank, Brookings Institution, attributed $229 billion in welfare expenditures between 1970 and 1996 to the breakdown of marriage.

Yes indeed. Stable families are less likely to be on welfare. As Ron Haskins and Isabel Sawhill of Brookings write,

Our research shows that if you want to avoid poverty and join the middle class in the United States, you need to complete high school (at a minimum), work full time and marry before you have children. If you do all three, your chances of being poor fall from 12 percent to 2 percent, and your chances of joining the middle class or above rise from 56 to 74 percent.

But DeMint and other social conservatives make a logical leap when they connect that point to gay marriage. Gay people making the emotional and financial commitments of marriage is not the cause of family breakdown or welfare spending.

When DeMint says that “family breakdown” is causing poverty – and thus a demand for higher government spending – he knows that he’s really talking about unwed motherhood, divorce, children growing up without fathers, and the resulting high rates of welfare usage and crime.

So why raise the problems of broken families and then propose to prevent gay people from getting married? Why all the focus on issues that would do nothing to solve the problems of “family breakdown” and what DeMint has elsewhere called “the high cost of a dysfunctional society”? Well, solving the problems of divorce and unwed motherhood is hard. And lots of Republican and conservative voters have been divorced. A constitutional amendment to ban divorce wouldn’t go over very well with even the social-conservative constituency. A legal ban on premarital sex would address the problem, but even social conservatives realize that it would be an imprudent exercise of state power. Far better to pick on a small group, a group not perceived to be part of the Republican constituency, and blame them for social breakdown and its associated costs.

But you won’t find your keys on Main Street if you dropped them on Green Street, and you won’t reduce the costs of social breakdown by keeping gays unmarried and not letting them adopt orphans.