Anthony Esolen argues that racial segregation was based on an irrational—indeed, peculiar—prejudice, and thus is not analogous to the conviction that marriage should be reserved for one man and one woman, which is based on universal truths about human nature. He writes, “I fear that our age is so enslaved to ideology that we can no longer notice what is obvious and natural, or think sensitively about history, or craft analogies that can stand a moment of analysis.”

Consider the segregationist in Alabama, who wanted to keep one water fountain (the nice one in the middle of the hall) for whites, and another (the rusty one out back) for colored people. What can we say about that?

What the southern slaveholders themselves said about it, for one: it is a peculiar institution. It is not part of the universal human experience, this uncharitable preoccupation with race.

Ancient Rome knew nothing of it. Does anyone know the color of Saint Augustine’s skin? He was born in Africa to a father with a Roman name and a mother with a Punic name. Was his blood Caucasian, Semitic, Berber, Ethiopian, or some combination thereof? No one knows, because no one thought it worth mentioning. After the first century, none of the emperors are specifically Roman, and very few are even Italian. No one cared.

The ancient Greeks, more prone to ethnic vanity, still knew nothing of racial obsession. They considered people who were not Greeks to be “barbarians,” literally those whose speech sounds like bibble-babble, but their vanity was not based upon race. They thought that people who did not live in a free, self-governing polis were to be pitied; they were missing the blessings of a vibrantly human life. Those Greeks were far more interested in the customs of Egyptians and Persians than the other way around. They were like Odysseus, passionate to learn the ways of men.

People will always find ways to distinguish themselves from their “lesser” brothers, but the bizarre racial touchiness that characterized the American South, or that hardened into the caste system in India, a mingled modus vivendi and modus odiendi, is uncommon in human affairs. It is certainly not universal.

Second: Jim Crow laws were based upon irrational “science.”

A whole legal and cultural system had to support the tottering edifice of a lie. The lie was simply that the differences between Joe Louis and Max Baer were more than epidermal or physiognomic. Louis and Baer were to be considered wholly different kinds of human beings, with different kinds of lips and throat and stomach at their water fountains. That is nonsense.

Third: the separation violated the natural law.

The water fountain is designed to meet the natural bodily needs of a human being. Everyone needs to drink. Thirst is far more distressing than hunger. Every traveler or stranger needs a place to sleep. Every sick person needs a bed and a doctor. The black man needs water, or food, or a bed, or medicine no more and no less than does the white man, and for the same reasons. The right to these things, without any encumbrance based upon the fantasy of race, flows from our common human nature. I was thirsty, and you gave me to drink.

Fourth: the whole purpose of maintaining separate water fountains was to maintain the racist culture.

It did not touch upon the common good in any other respect. The discrimination was its own end. Now, a prudent statesman may have to discriminate according to nationality, but not for the sake of the discrimination. Let’s suppose that you shut off all immigration to the United States from Qatar. It need not be that you hate the Qatari people, or that you hate Muslims. You may be concerned that Qatar happens to be an oasis for terrorists in training. So your prohibition is aimed at a particular, specific end: preventing terrorists from entering the United States. In another decade, you might be glad to admit Qatari immigrants by the thousands. That was not the case with the southern segregationists, who wanted to extend their peculiarity forever.

You can read the whole thing here, where he goes on to argue that none of these conditions characterize the defense of conjugal marriage, which is not peculiar but universal.