The most prominent argument against allowing same-sex couples to marry is that it somehow harms traditional marriage. Nate Silver argues that the anecdotal evidence would suggest just the opposite: A tolerant view of marriage coincides with lower divorce rates.
Over the past decade or so, divorce has gradually become more uncommon in the United States. Since 2003, however, the decline in divorce rates has been largely confined to states which have not passed a state constitutional ban on gay marriage. These states saw their divorce rates decrease by an average of 8 percent between 2003 and 2008. States which had passed a same-sex marriage ban as of January 1, 2008, however, saw their divorce rates rise by about 1 percent over the same period.
The table below details the divorce rates for the 43 states that reported their divorce statistics to the CDC in both 2003 and 2008. It is calculated by taking the total number of divorces in the state that year, and dividing it by the number of married persons, as reported by the Census Bureau. The result is then multiplied by two, since each divorce involves two people. This is different than how the divorce rate is sometimes calculated, which may be as a share of the overall population rather than the number of married persons; I prefer my approach because it will not penalize a state for having a lot of marriages (and therefore more opportunities for divorce).
Visually, the correlation looks pretty spotty. Virtually all of the states have affirmatively banned gay marriage and a goodly number have also banned civil unions. They’re all over the rankings. Meanwhile, only five states have legalized gay marriage and they’re spread out pretty well, too. And the states at the very bottom, which have all banned gay marriage, increased by large percentages from very low baselines. (The exception being Nevada which should, of course, be tossed from the list since it’s a notorious divorce haven.)
Indeed, what’s remarkable from the list is how incredibly small the divorce rate as a share of marriages is across the board. Aside from Nevada, no state has a rate above 2.58% and most have rates under 2%.
But looks can be deceiving:
Overall, the states which had enacted a constitutional ban on same-sex marriage as of 1/1/08 saw their divorce rates rise by 0.9 percent over the five-year interval. States which had not adopted a constitutional ban, on the other hand, experienced an 8.0 percent decline, on average, in their divorce rates. Eleven of the 24 states (46 percent) to have altered their constitutions by 1/1/08 to ban gay marriage experienced an overall decline in their divorce rates, but 13 of the 19 which hadn’t did (68 percent).
But you’re dealing with some mighty small n‘s here. The top category has one case. The second category consists of 12 states but is utterly meaningless (what’s the difference between banning gay marriage in the constitution vice by statute?). The third category is virtually every state in the union.
Beyond all that, Nate’s a much more adept statistician than I am. But even I know that doing correlation analysis to analyze sophisticated social phenomena is absurd. Unless we’re factoring in the variables known to impact marriage success rate (age at time of marriage, presence of children from prior marriages, different religious backgrounds, financial circumstances, race, prior cohabitation, etc.) so that we’re comparing apples to apples, we have no way of knowing what impact, if any, the legal status of gay marriage has on the overall divorce rate.
Indeed, Nate admits this:
The differences are highly statistically significant. Nevertheless, they do not necessarily imply causation. The decision to ban same-sex marriage does not occur randomly throughout the states, but instead is strongly correlated with other factors, such as religiosity and political ideology, which we have made no attempt to account for. Nor do we know in which way the causal arrow might point. It could be that voters who have more marital problems of their own are more inclined to deny the right of marriage to same-sex couples.
But that doesn’t make sense. They’re anti-gay, after all. Why would they want to save gays from an institution that they personally find intolerable? The much more plausible explanation is that they honestly think gay marriage is immoral and they want to preserve matrimony as a sacramental relationship.
