Outside the world of sports, the question of women reporters being barred from the locker room after the ball game is hardly earthshaking. Nevertheless, feminists and others concerned with equal rights have raised it as a significant challenge to women's equality.

I think it is significant for another reason - an example of how ideology has made common-sense discussions of discrimination impossible.The case of Lisa Olson, sportswriter, is well-rehearsed. While she was trying to conduct a locker-room interview, several unclothed New England Patriots players allegedly subjected her to lewd gestures and sexual innuendo.

Two weeks later, the Cincinnati Bengals coach banned another woman sportswriter from his locker room. The NFL dutifully slapped him with the largest fine an NFL coach has ever received.

National press reaction has been near unanimous. Even ordinary newscasts cannot avoid expressions of contempt not just for the Patriot harassers (who deserve it), but for the Neanderthal coach who would contemplate discriminating against women in the 1990s.

In a typical reaction, one New York Times sports columnist compared barring women from the locker room to the barring of blacks from professional sports in days gone by. Discrimination is discrimination.

Nonsense. Some discrimination is wrong and some is not. Discrimination is only wrong when irrational, when used for the sole purpose of keeping selected and disfavored groups of people down, abused and excluded.

Discrimination by race, for example, is always irrational and therefore wrong. (The exceptions to this rule are technical and trivial: e.g., choosing subjects for sickle-cell anemia or Tay-Sachs research on the basis of race and ethnicity.)

Feminism, riding the success of the civil-rights movement and adopting its ideology and tactics, tries to imply that discrimination on the grounds of sex is intrinsically wrong as well.

But it is intrinsically wrong only when there is no rational basis for such discrimination. The difference between black and white people is trivial. The difference between men and women is not.

On some occasions, therefore, these real differences provide a rational and therefore defensible basis for discrimination on the basis of gender. For example:

- We exclude women from combat, even knowing that such discrimination inevitably retards women's career advancement in the military.

- Some colleges will admit no men.

- And when it comes to sexual privacy, we discriminate on the grounds of gender all the time. We keep men out of women's bathrooms and women out of men's. If a woman finds the women's bathroom occupied, she must wait. She does not have resort to the next-door men's bathroom even if it is free. She is barred from it solely on the grounds of gender.

It is simply common sense that we restrict men and women's access to each other in certain conditions, particularly conditions of public undress.

Women athletes, in particular, seem to insist on it. I have made inquiries to several top women's basketball teams. I have yet to find one that allows reporters in its locker room (though at the NCAA tournament they are mandated by the NCAA to allow reporters in for about 15 minutes).

For men to come into a women's locker room, says Jody Conradt, coach of the University of Texas women's basketball team, would be "totally inappropriate."

One of the country's top sportswriters tells me that he once accidentally wandered into Chris Evert's dressing area. She screamed at him to get out. He did not scream back: "equal access." He left.

Sex discrimination in sports goes far beyond the locker room. In tennis, for example, there are two individual titles at the U.S. Open. The women's champion gets the same prize money as the men's. The men have to work harder (they play five sets per match, the women three) and face stiffer competition.

But if you are a man, you cannot enter the weaker women's division. A mediocre male player who might well win on the women's circuit is barred purely on the grounds of sex.

Why does no one protest "discrimination"? Because there is good reason to discriminate by sex in championship tennis (and basketball and shot put and marathon). If you didn't, women could not compete.

When a good purpose is served and when sex differences are relevant, sex discrimination and sex segregation make sense. In fact, they are necessary for the orderly and civilized conduct of society.

Common sense and ordinary practice keep unclothed men and women segregated in public places. Barring women from locker rooms of male athletes is entirely consistent with American norms of sexual privacy.

At the same time, barring women from the locker room would be a severe competitive disadvantage to women sportswriters. (Only the men would get locker room quotes.) What to do?

The obvious solution is to bar everyone from the locker room. Conduct the interviews elsewhere, later, in a state of dress. If that solution is so prudish, retrograde and anti-feminist, how is it that women's teams insist upon it?