There's a strategic reason for that dogmatic assertion. As long as people believe that men and women are biological clones, the rad-fems can claim that the under-representation of female CEOs and politicians can be blamed on the Glass Ceiling, not on the informed lifestyle choices that women make.
And that in turn justifies the gender quotas, government set-asides, and all the other appurtenances of a feminist society.
The feminist thought police do not take kindly to persons who challenge widely-held beliefs. So when Harvard president Lawrence Summers suggested innate sex differences, not gender socialization patterns, might account for the shortage of female scientists, the Lefties were aghast.
But scientists insist Summers has a point, that the brains of men and women are anatomically and functionally different. Referring to the spatial abilities of the sexes, Judith Kleinfeld of the University of Alaska notes, "The average difference between males and females on psychological tests of these abilities is huge."
The Summers' dust-up has broadened into a broad-based examination of sex and gender. That argument is now being waged on two other fronts.
First is the Great Op-Ed Debate, that non-stop catfight that has been trying to answer the vexing question, Why do women represent only a small fraction of newspaper opinion writers?
Of course, there were the pundits like Amy Sullivan who predictably played the victim card. Sullivan blamed the problem on women who "have been raised to feel ill-at-ease in the rough-and-tumble, male-dominated world of political expression." Sorry, Ms. Sullivan, that argument may have played in Peoria 50 years ago, but not in 2005.
Others searched for more plausible explanations.
Gail Collins, the woman who runs the editorial page of the New York Times, admitted in a round-about way, "There are probably fewer women, in the great cosmic scheme of things, who feel comfortable writing very straight opinion stuff."
And Maureen Dowd, whose writing style is perpetually stuck in full-attack mode, sounded more like a purring kitten when she admitted, "I wanted to be liked, not attacked...This job has not come easily to me."
But it was Catherine Seipp who finally came out and stated the obvious: "The uncomfortable fact is that women just seem less interested in politics than men." Why? Because "that typically female emotional-reaction-as-argument is one big reason why the op-ed pages are still mostly male."
By remarkable coincidence, the Great Op-Ed Debate was being waged just as the journal Nature was about to release the startling results of a study that would profoundly challenge the basic feminist assumptions of gender.
That research, published late last month, found the inborn differences between men and women are far greater than previously suspected. Men and women differ by two percent in their genetic make-up.
And here's the jaw-dropper: That two percent sex difference is greater than the biological gap between humans and chimpanzees. In other words, the built-in differences between men and women are akin to the dissimilarities between man and ape.
Now we know why millions were so engrossed by that long-running TV series about Tarzan, Jane, and Chita.
First Larry Summers. Then the Great Op-Ed Debate. And now breakthrough research on the genetic differences between the sexes.
It's high time that we accept the obvious: Men and women are not the same. Vivre la difference!