Adventures in math and marriage: or why gay does marriage does not decrease straight marriage.

DOES THE LEGALIZATION OF GAY marriage contribute to the decline of heterosexual marriage? A good portion of our fair republic's cultural conservatives seem to believe that it does. Evangelical radio personality James Dobson, head of Focus on the Family, told a typically credulous Larry King in November of 2006: "In the Netherlands and places where they have tried to define marriage [to include gay couples], what happens is that people just don't get married. It's not that the homosexuals are marrying in greater numbers, it's that when you confuse what marriage is, young people just don't get married."

If what Dobson says is true, New Jersey is going to be in huge trouble, and Massachusetts, which legalized gay marriage in 2004, must already be. Of course, Dobson is wrong. Here's why.

First, let's think about this problem mathematically and prepare our variables. X is any country "where they have tried to define marriage [to include gay couples]," in Dobson's description. Y is the marriage rate among heterosexuals before country X has "tried to define marriage [to include gay couples]," and Z is the allegedly decreasing heterosexual marriage rate that exists after ten years of gay civil unions. The Dobson Theorem, as we shall call it, states that "if X, then Y must be greater than Z." Or, translating math into English, "If a nation allows for civil unions, the marriage rate among heterosexuals at the time that this occurs will be higher than it is ten years later."

Let us now test the Dobson Theorem. Like most things with variables, the Dobson Theorem requires that X be substituted for various things that meet the parameters of X--in this case, northern European countries. Luckily, Dr. Dobson himself has provided us with some data. During the Larry King interview, Dobson mentioned Norway and "other Scandinavian countries" as fitting the description. We'll also need values to punch in for Y and Z. These may be obtained from all of the countries in question, which have famously nosy governments. Conveniently enough, these numbers may also be obtained from the October 26, 2008 edition of the Wall Street Journal op-ed page, where William N. Eskridge, Jr., the John A. Garver professor of jurisprudence at Yale University, and Darren Spedale, a New York investment banker, penned an editorial based on their new book entitled Gay Marriage: For Better or For Worse? What We've Learned From the Evidence.

According to Eskridge and Garver, Denmark began allowing gay civil unions in 1989. Ten years later, the heterosexual marriage rate had increased by 10.7%. Norway did the same in 1993, and a decade later the heterosexual marriage rate had increased by 12.7%. Sweden followed suit in 1995, and ten years later the heterosexual marriage rate had increased by 28.7%. And these marriages were actually lasting. During the same time frame, the divorce rate dropped 13.9% in Denmark, 6% in Norway, and 13.7% in Sweden. So, we can reject the Dobson Theorem. But how did Dobson get this relationship so wrong in the first place?

The culprit may be the Weekly Standard and National Review gadfly Stanley Kurtz, who took issue with Garver and Eskridge's preliminary findings back in 2004, before they were published. Confronted with statistics indicating that marriage in Scandinavia is in free shape, Kurtz instead proclaimed that "Scandinavian marriage is now so weak that statistics on marriage and divorce no longer mean what they used to." Brushing aside numbers showing that Danish marriage was up 10% from 1990 to 1996, Kuttz countered that "just-released marriage rates for 2001 show declines in Sweden and Denmark." He failed to note that they were down in 2001 for quite a few places, including the United States, which of course had no civil unions at all in 2001. And having not yet had access to the figures, he couldn't have known that both American and Scandinavian rates went back up in 2002. As for Norway, he says, the higher marriage rate "has more to do with the institution's decline than with any renaissance. Much of the increase in Norway's marriage rate is driven by older couples 'catching up.'" It's unclear exactly how old these "older couples" may be, but at any ...