America - Andrew Stephen watches the paper line up to vote

If academia were truly free-thinking, it would accept that the possibility of innate differences bet

I visited Princeton University the other day for the first time in 30 years. It was remarkably refreshing to be in what appeared to be a free-thinking community, away from the increasingly crabby and right-wing diktats of George W Bush's America: for a briefly indulgent afternoon, I felt at home.

But I've never been entirely convinced about how free-thinking academia here really is, and before long my doubts returned. This time my attention was caught by the description of a meeting near Harvard University that was being addressed by Larry Summers, the president of Harvard and a former treasury secretary in the Clinton administration. Nancy Hopkins, a professor of biology at MIT, was so disgusted by what she heard that she had to leave the room in a hurry. "I felt I was going to be sick," she explained. "My heart was pounding and my breath was shallow." It was all so bad that, had she not fled the hall so hurriedly, "I would've either blacked out or thrown up".

What had made the professor so ill? In the meeting, Summers suggested that "innate differences" between men and women might be the reason why so few women hold top posts in science and maths in American universities. The outrage was immediate, spurred not just by Hopkins, but by more than 100 Harvard professors who also complained. Summers had to grovel left, right and centre, publicly apologising, by my count, at least three times.

The most outrageous thing about this episode, however, was not what Summers said - but the reaction. He suddenly became a pariah, hated by supposedly free-thinking academics everywhere. Yet what he suggested was that the issue merited academic study; he was not claiming to know the truth. But the very idea had to be exorcised by those who espouse the orthodoxies of American academia. There is even speculation that Summers will lose his job.

We all know that there are differences between males and females - not only physically, but probably in the way our brains work, too. I am told, for example, that female finches are disastrously inept singers; male finches warble superbly. Female elephants have stupendous vocabularies in elephant language; male elephants are monosyllabic by comparison. With human beings, females' brains are smaller than (but not necessarily inferior to) males' brains.

Yet so many here cling to the idea that boys and girls are the same, usually until they become parents of both themselves. I do not see how it is insulting to either gender to suggest that they might assimilate information differently: among college-bound high-school pupils here, boys do far better than girls in maths tests, but the girls score better at languages. Boys are also much more likely to be hyperactive, dyslexic and autistic.

So why, when such intriguing issues are raised, is there such stifling of free thought on American campuses? I suspect it is because Americans like to live by rules. They learned a generation or two ago that they should not be racist or sexist. By and large, they try to abide by these rules, though you have to live deep in American society to recognise the subtle codes that so many people use to surmount them: "teen pregnancies" or "welfare dependency" become code for "blacks", while "neoconservative" and "Hollywood" frequently mean "Jew".

Yet the definitions of the rules change, and a repressive uniformity that may not be in keeping with original ideals takes over. In this way, certain types of sexual discrimination then become acceptable. Is it really because women are innately cleverer than men that markedly more women are now accepted into colleges in the US? Maybe, but it could also be because there is sexism against males; this clearly needs to be investigated.

I acknowledge that I may be wrong about innate gender differences, and accept that singing finches are not necessarily a good guide to human behaviour. But why are there comparatively few women in the maths and science departments of American universities? Is it because men discriminate against women, keeping women out of those departments? Because women, straitjacketed by their upbringings, believe science is not for them, and have an absence of female role models to show them otherwise? Or because they have more important things to do, such as child-rearing? Do they simply find maths and science boring, and choose to leave them to nerdy males?

These are fascinating questions, but we will not have any serious research into them - certainly not at Harvard. The truth might upset any or all of us. But instead of discovering new truths, we endure the spectacle of the Harvard president grovelling to those who want to see the matter closed. No inquisitiveness, no wish to widen our knowledge. What a commentary on American academia in 2005.