Faced with the prospect that Illinois will become the next state to legalize same-sex marriage, Cardinal Francis George of Chicago is bringing out the big Catholic rhetorical gun: Natural Law. It needs to be spiked.
"Marriage comes to us from nature," His Eminence told Chicago Tribune religion reporter Manya Brachear over a cup of tea. "That's based on the complementarity of the two sexes in such a way that the love of a man and a woman joined in a marital union is open to life, and that's how families are created and society goes along. … It's not in our doctrine. It's not a matter of faith. It's a matter of reason and understanding the way nature operates."
"The State," he wrote in a letter to all the priests in his archdiocese, "has no power to create something that nature itself tells us is impossible."
The purpose of such an appeal to Natural Law is simply to claim a rational, i.e. secular, basis for supporting or opposing a societal practice that the Church happens to support or oppose. Rationalistic theologians like the 13th-century Dominican Thomas Aquinas, building on the work of ancient Greek philosophy, contend that God has embedded moral truths in nature and that all people can discern them by the light of reason alone.
Among other things, Aquinas used Natural Law to justify burning heretics at the stake. The first-century Hellenistic Jewish philosopher Philo of Alexandria went so far as to claim that Abraham the Patriarch obeyed God's commandments "not having been taught to do so by written books, but in accordance with the unwritten law of his nature."
In a society like ours, where appeals to religious doctrine per se have no standing in civil law, it's super to be able to claim that your religious positions are actually built into the nature of things. The trouble is that Natural Law arguments can and have been used to rationalize many sides of a moral question: slavery and anti-slavery; the subordination of women to men and women's equality; the segregation and desegregation of the races, you name it.
On New Year's Day, Pope Benedict criticized "an unregulated financial capitalism" for causing "tension and conflicts" at odds with "the duty and right to an integral social and communitarian development, which is part of God’s plan for mankind." And yet there are good libertarians who reason that Natural Law is all in favor of unfettered capitalism.
When it comes to marriage, you could argue that Natural Law favors men having as many "wives" as possible, even as it favors women picking the best guy they can find every nine months or so. The sociobiologists, who might have a better line on Nature than Cardinal George, sometimes make out a case along those lines. And there's sufficient same-sex genital behavior in the animal kingdom for them to claim that Natural Law prescribes a certain amount of homoeroticism as well.
Of course, Cardinal George is no more likely to accept the reasoning of the sociobiologists than Pope Benedict is likely to accept the reasoning of (sorry, Rep. Ryan) Ayn Rand. Their positions on same-sex marriage and unfettered capitalism are fixed--doctrinal, you might say.
Appealing to Natural Law is, as it always has been, about the rationalization of societal values that the appellant holds for reasons that have little or nothing to do with reason. When you hear Natural Law being used to justify some public policy or other, there's no reason to take it seriously.