In the name of civil discourse, The Washington Post recently denounced Kenneth Cuccinelli, now the next Attorney General of Virginia. Cuccinelli said that some behavior is "intrinsically wrong" and he described the U.S. as "a natural law based country." According to the Post such reasoning is out of bounds, for "appeals to ’natural law’ and ’intrinsic’ rights and wrongs were the usual cliches deployed to justify the old-time religion of hatred then directed at African Americans, Jews, Italians, Irish and other immigrants."

That critique is uninformed and unhelpful, and leans more on bigotry than on sound history. Hatred of Jews, Italians, Irish and other immigrants seldom, if ever, drew upon natural law. To be sure, it was often done in the name of science, but that’s not the same thing as natural law. In the early 20th century, scientific racists and eugenicists turned to Darwin, not Aristotle for support.

American historians usually present the Scopes "monkey" Trial of the 1920s as a fight between the forces of light (science) and the forces of darkness (religion). There’s more to the story. Part of the reason William Jennings Bryan opposed the teaching of Darwin in the schools is that Darwin was being used against natural law teaching, and in support of scientific racism and eugenics. At the trial, the three-time Democratic nominee for president denounced the "barbarous sentiment that runs through evolution." It will not do simply to assert that science = good = progress. Sometimes, as Bryan knew, what is called science is mistaken. To be sure, the eugenic reading of Darwin was a perversion of Darwin. It was, however, quite popular in Progressive circles, which took it to be the most current science. Those who disagreed were mocked for being anti-science. Bryan’s "old-time religion" was hopelessly out of date.

The connection of racism and natural law is a bit more complicated. Once again, in the Progressive era, many cutting-edge thinkers used Darwin, and not natural law, to support eugenics. Margaret Sanger, who once addressed a Ku Klux Klan rally, seems to have flirted with the idea. She lamented that "the increase in Negroes, even more than among whites, is [in] that portion of the population least intelligent and fit." It is also true that anti-miscegenation laws often held that inter-racial marriage was "contrary to nature." Such laws at least used the language of natural law. But if we allow that mistaken readings of Darwin ought not to be used to read Darwin out of polite discourse, must we not give the same courtesy to natural law?

We should also note that the scientific racism upon which anti-miscegenation laws drew was not a classic element of natural law. On the contrary, it first appeared in the eighteenth century, and it drew upon the modern scientific method, not Aristotle’s, or even Thomas Aquinas’ approach to science. That’s why it is associated with Thomas Jefferson, the most progressive of the founders in matters scientific, and not with John Adams, the most traditional in such matters. Jefferson was making a (mistaken) effort to move moral ideas forward in light of modern science. Adams held that such science cannot change.

What is natural law? Classically speaking, it draws upon Aristotle’s idea that "nature does nothing in vain." By studying the natural order, this science holds, one can determine what is good by nature. The classic natural law teaching against homosexual conduct, to which Cuccinelli referred, comes from the observation that all "higher" species have male and female, and that, since there is logic in nature, we may conclude that the male and female organs are made for each other. Hence homosexual acts are "contrary to nature."

Is he correct? Many good and intelligent people have been on Cuccinelli’s side, but many enlightened people, especially today, think he’s wrong. Is it wise to be certain that the older idea is wrong? When we turn from the physical to the moral world, after all, modern science does not, and cannot, give us guidance. That’s why Darwin led so many Progressives astray. We would like to have scientific answers to the most important questions, but modern science cannot provide them. That, however, is the larger point. Both sides could use a little humility. Honest people of good will are on both sides of these debates. Reading natural law out of civil discourse is not the way to encourage open, honest, and helpful debate. To suggest that natural law is nothing more than a cover for narrowminded bigotry is, well, narrow minded and bigoted.

President Lincoln said that "if slavery is not wrong, nothing is wrong." To treat a human as a slave is to treat him or her the same way as one treats an animal—a violation of the natural order. In that sense, Lincoln agreed with Cuccinelli that we’re "a natural law based country." Most of us, I suspect, would agree with Lincoln. Perhaps it would be more fruitful to debate what is intrinsically wrong and not whether anything is intrinsically wrong, and to stop trying to shut up people with whom we disagree.

Richard Adams is a regular contributor to the Ashbrook Center’s blog, No Left Turns.