This is a central idea of the rape-crisis movement: that sex has become our tower of Babel. He doesn’t know what she wants (not to have sex) and she doesn’t know what he wants (to have sex) — until it’s too late. He speaks boyspeak and she speaks girlspeak and what comes out of all this verbal chaos is a lot of rapes. The theory of mixed signals and crossed stars has to do with more than gender politics. It comes in part, from the much-discussed diversity that has so radically shifted the social composition of the college class since the 50’s.

Take my own Harvard dorm: the Adams House dining hall is large, with high ceilings and dark paneling. It hasn’t changed much for generations. As soon as the students start milling around gathering salads, ice cream and coffee onto green trays, there are signs of change. There are students in jeans, flannel shirts, short skirts, girls in jackets, boys in bracelets, two pierced noses and lots of secondhand clothes.

Not so many years ago, this room was filled with boys in jackets and ties. Most of them were white, Christian and what we now call privileged. Students came from the same social milieu with the same social rules and it was assumed that everyone knew more or less how they were expected to behave with everyone else. Diversity and multiculturalism were unheard of, and if they had been, they would have been dirty words. With the shift in college environments, with the introduction of black kids, Asian kids, Jewish kids, kids from the wrong side of the tracks of nearly every railroad in the country, there was an accompanying anxiety about how people behave. When ivory tower meets melting pot, it causes tension, some confusion, some need for readjustment. In explaining the need for intensive “orientation” programs, including workshops on date rape, Columbia’s assistant dean for freshmen stated in an interview in The New York Times: “You can’t bring all these people together and say, ‘Now be one big happy community,’ without some sort of training. You can’t just throw together somebody from a small town in Texas and someone from New York City and someone from a conservative fundamentalist home in the Midwest and say, ‘Now without any sort of conversation, be best friends and get along and respect one another.’ ”

Catharine Stimpson, a University Professor at Rutgers and longtime advocate of women’s studies programs, once pointed out that it’s sometimes easier for people to talk about gender than to talk about class. “Miscommunication” is in some sense a word for the friction between the way we were and the way we are. Just as the idea that we speak different languages is connected to gender — the arrival of women in classrooms, in dorms and in offices — it is also connected to class.

When the Southern heiress goes out with the plumber’s son from the Bronx, when the kid from rural Arkansas goes out with a boy from Exeter, the anxiety is that they have different expectations. The dangerous “miscommunication” that recurs through the literature on date rape is a code word for difference in background. The rhetoric surrounding date rape and sexual harassment is in part a response to cultural mixing. The idea that men don’t know what women mean when women say no stems from something deeper and more complicated than feminist concerns with rape.