Why is the transgender issue so hot? Much of it has to do with the reality that sex and race are not merely very different things, but also they are different kinds of things. Sex is a biological reality; race is largely a cultural phenomenon. The trouble is that our civil rights laws—and the culture that follows from those laws—are uncomfortable with that reality. It is not that we never allow discrimination on the basis of sex—otherwise there never would be any single-sex bathrooms or colleges. But we have a strong bias against allowing sex to matter. Our fights over transgender athletes bring this reality into stark relief.

Consider the argument that trans women ought to have the right to compete in women’s and girls’ sports. What is the argument? It is that gender (not biological “sex”) is fundamentally about self-understanding, and that discrimination on the basis of sex or gender, like discrimination on the basis of race, is always wrong. Hence to exclude Lia Thomas, a biological male who identifies as female, from competing in women’s sports is no different than going back to the days when Major League Baseball forced black ballplayers to play in a different league. In other words, when people make the argument that “trans women are women” they are asserting that it is always nothing more than bigotry to distinguish between women and trans women. It’s no different from assigning separate drinking fountains or locker rooms on the basis of race

A significant majority of Americans find this position to be unreasonable. Biological sex does matter, particularly in sports, or in locker rooms, or, for that matter, in prisons. It is an objective fact that, physiologically speaking, biological men and biological women develop differently, and do so in ways that make the men, on average, stronger and faster. And it is also the case that many women will, inevitably, be uncomfortable when they have to share locker rooms and prison cells in which they shower and change with naked people who are genitally indistinguishable from men. From this point of view, it is often good and necessary to segregate by biological sex, a truth that does not apply to discrimination on the basis of race, which is wrong in itself.

As, on average, a biological man is likely to be physically stronger than a female, if there are going to be women’s sports, it is necessary to separate trans women from other women. And this is precisely where we see why it is such a bad idea to be inclined to treat sex and race as if they were the same when it comes to discrimination. To exclude black women from competing against white women in a swim meet, or to prevent a black man from competing against a white man, merely because of race, would be racism, pure and simple, and those who did it would justly be excoriated. Applying that standard to trans athletes makes sense if, and only if, race is no different than sex. Common sense suggests that’s absurd. As the old line has it, Only an intellectual could be stupid enough to believe it.

There is a deeper issue here. Race is cultural and historical. In America, race is fundamentally about tribal identity, and about discrimination on the basis of skin pigmentation and African ancestry. Hence racial discrimination is fundamentally irrational and immoral. That the United States has a legacy of racial caste, both in the era in which slavery was legal and in the era after, is shameful. To remedy that history, we, among other things, passed the Civil Rights Act of 1964. That act also banned discrimination on the basis of sex, and the ideology of equality that our enforcement bureaucracy has developed is very uncomfortable with the truth that there are cases in which sex and race need to be treated differently.

Why did a judge in Washington state decide that a female-only spa, where women walk around naked, must allow men who identify as women as customers? It is because the judge is treating sex segregation as if it were race discrimination. Why was a biology professor in Texas fired for saying that male and female dimorphism is determined by chromosomes? Because the school believes that to say that is no different from saying that black people and white people are different biological types. 

The trouble is that there are, in fact, real differences between men and women, of a sort that simply do not exist regarding race. There are outlying cases, but, on average, and across the world, men tend to be taller, have more muscle mass, and are faster, among other things. We also have different body chemistries. Increasingly, science is recognizing that our brains also work differently. Overall, we have the same average intelligence, but we probably also have, on average, different tendencies in our personalities and habits, and ways of relating to others.

Is a tendency to like “dad jokes” a matter of culture, or does it reflect a biological tendency? Is it nature or nurture that is responsible for the reality that, in America today, over 80 percent of social workers are female? Just the other day, Joyce Carol Oates noted that there is “a male preoccupation with certain phases of history (Civil War, Nazis, Hitler) & reenactments of battles.” How often does a woman say, “hey gang, watch this,” before doing something dangerous, stupid, or asinine? Such differences might be cultural, or they might be grounded in nature, but we ought not to assume it’s all culture.

If today’s studies of sex differences are advanced enough, and if they are confirmed moving forward, they might help us judge if there are, in fact, professions, college majors, and the like in which we are likely to see more women than men, or more men than women. If science is not there yet, it’s probably wise to pause and consider the possibility that the presence of more women than men or more men than women in a given profession or, perhaps more often, within a specific profession, might not be a sign of invidious sex discrimination or a patriarchal legacy. It is one thing to get rid of laws that prohibit or discourage women from becoming doctors or lawyers, or from owning land, or pursuing their vocational dreams. But it is quite another to assume that all fields and sub-fields ought to have the same number of men and women.

In other words, especially in light of the way we use disparate impact analysis (the assumption that statistical disparities among groups are evidence of discrimination) as a tool of civil rights enforcement, and in light of the rising number of transgender Americans, we might very well have to consider separating race from sex in our anti-discrimination law, separating out those cases in which discriminating between male and female is as wrong as discriminating between people due to race from those cases in which it is not.