In the middle of 2014, the chattering classes were gripped by Ta-Nehisi Coates’ outstanding essay "The Case for Reparations," which outlined the history of oppression faced by African-Americans and argued for finally coming to some collective recognition of the evils done to slaves and their descendants. At the end of 2014, many of the same people are debating a 20-year old book of social science, which argues, among other things, that African-Americans as a whole have IQs that fall one standard deviation lower than European-Americans.

How did we get here? It began with The New Republic magazine imploding earlier this month, which led many of its former writers and editors to eulogize it as one of the great vehicles for American letters. Other writers, most prominently Coates, countered that we shouldn't mourn a magazine that was so intent on blaming the degraded social position of African-Americans on black themselves, rather than on policies motivated by the racism of whites.

The most notorious example was former TNR editor Andrew Sullivan’s decision to dedicate an issue of the magazine to debating The Bell Curve, a 1994 book by Charles Murray and Richard J. Herrnstein that argued that there are persistent aggregate IQ differences between races. The implication was that in an age in which social and economic rewards increasingly accrue to a cognitive elite, social policy aimed at achieving equality of outcome across races is doomed to fail.

Sullivan recently defended himself by saying that he believed that liberalism could be improved if all debates are aired fairly. Fredrik de Boer, a leftist writer, argued in a slightly different vein that the thesis of The Bell Curve had to be debated precisely because it reflects a powerful and regnant prejudice. By enforcing a taboo against "legitimizing" its thesis through debate, opponents of its theory of an inherited racial intelligence hierarchy were ceding the field to racists and self-appointed "realists" like Nicholas Wade.

Coates began strafing Andrew Sullivan on Twitter, pointing out that lots of ugly and idiotic theories that play a role in oppression are not debated. And then Coates wrote this:

Other writers like Jamelle Bouie took a similarly caustic view. As rhetoric, this is very powerful. Coates could have pushed it further and combined this with his exploration of the history of white theft of black wealth, and say that The Bell Curve is not only an implicit argument against ameliorating the effects of racial inequality and injustice, but a logical pathway to taking more resources from African-Americans. After all, in another time, one of the theories used to justify the forced removal of Native Americans from their lands was that they were not properly exploiting the land they controlled. Popular defenses of gentrification can have a similar ring.

But there are problems with Coates' approach. First, we should be careful to distinguish the native intelligence of an individual or group from their humanity. Having an IQ score of 88 does not make one less human than someone scoring 108. It makes one no less deserving of human rights and citizenship.

Understandably, Coates conflates an argument about the IQ of blacks with an argument about their humanity precisely because the advocates for white supremacy do the same. Coates knows that historically the men who offer theories of black inferiority are often the same men offering blacks a separate and much crueler justice system. Those who say that nature simply dooms blacks to a lower social place are usually the ones most fanatically exerting themselves to confine blacks to it.

But it would be not be difficult to eliminate the statistical noise of socially constructed racial categories from the equation, and simply rate individuals according to IQ or some other meritocratic ranking. We could find people of lesser mental ability much more efficiently than by making guesses from a supposed racial hierarchy where there still is so much ambiguity and overlap. And once found, we could abuse them. Some of the same villains who wanted to sterilize blacks in the eugenics programs of the American South were eager to sterilize other "mental defectives" among their own race.

In other words, there may be billions of people with lesser mental ability than Ta-Nehisi Coates. Some day it may be easy to identify them. All the more reason to ground our political and social claims in a shared humanity, regardless of ability.

As the study of genetics advances, as well as the environmental factors that play a role in genetic expression, we are likely to have even more uncomfortable debates about fate and history. Look to the Korean Peninsula, where a genetic population much smaller than a broadly construed race has been divided by ideology and wealth. Those experiencing North Korea’s deprivation and cruelty are becoming physically shorter and smaller than their counterparts in the South. It is a difference that may be caused by malnutrition, but that also has far-reaching hereditary consequences. North Korean refugees are so recognizable by differences of speech, culture, and size that they are a kind of visible minority in the South, and experience discrimination in hiring.

If it were discovered that the combined environmental factors of deprivation, malnutrition, and madhouse oppression were depressing the aggregate intelligence of North Koreans, would you be surprised? I doubt it. But such a discovery would be an unanswerable argument for ending the oppression of North Koreans, not an argument that the North Koreans are somehow less than human, or less dignified than their South Korean counterparts. In fact, it would be an awful testimony, carried in the blood for generations, that human dignity demands good government.

Such a discovery might also cut against any of the fatalism that underlies The Bell Curve itself. We would know that good policy does make a difference.

In any case, it's not good enough to suggest that, on balance, all groups of people and all nations are equal in the things that count in a modern meritocratic society. It is a categorical error to search out some material fact in the universe that is consonant with our egalitarian notions. That is just too shaky a foundation. The conviction that all men are possessed of equal dignity, and therefore deserve equality before the law, must be a political — or even theological — assertion against any fact of history or science that would tempt us to think otherwise. Political equality isn't something we discover in nature; it's something we must create.