Fact: if it weren't for the fictional existence of Mr Gradgrind, the writer Andrea Dworkin's enthusiasm for facts would be second to none. Fact: a while back, in an interview with Michael Moorcock, an admirer of hers, Dworkin said: "A big part of the fight was facing facts; and facts had a lot to do with what men had done to us, how men used us with or without our own complicity." Curious fact: on the Andrea Dworkin website, a whole section, "Lie Detector", is devoted to establishing what, in fact, Andrea Dworkin has, and has not, said or done.

Where possible, detailed evidence is offered. It's not true, for instance, that she once "flipped the finger" in a public debate with the Harvard law professor, Alan Dershowitz, and the website earnestly sets the record straight: "The photograph of the two them in Alan Dershowitz's autobiography, The Best Defense, actually shows Andrea making a characteristic gesture for emphasis."

Where photographic evidence is not available, the site relies on the author's written or spoken word. It is true, for example, that that Dworkin once prostituted herself on the streets, or as she has put it: "I fucked for food and shelter and whatever cash I needed." This personal experience, the website confirms, "is part of what informs the commitment behind all her writing". When she campaigns against pornography and prostitution, rape and abuse, Dworkin knows whereof she speaks: "The premises of the prostituted woman are my premises."

Her experiences at the hands of men have been more than horrible: diabolical. She was first raped at nine: "Though not legally," she writes in an autobiographical essay, "since fingers and a hand were used for penetration, not the officially requisite penis." She worked as a prostitute. In 1965 she was arrested and imprisoned after joining an anti-Vietnam war demonstration, then assaulted by the two male prison doctors who gave her an internal examination.

"They pretty much tore me up inside with a steel speculum and had themselves a fine old time verbally tormenting me as well." She married a brutal man, an "assassin", who battered and tortured her for several years, beating her with planks and burning her breasts with cigarettes, until a feminist helped her go into hiding: "Every trip outside might mean death if he found me". In 1972 she made a vow, "that I would use everything I know in behalf of women's liberation".

It's a vow she has kept. "Autobiography is the unseen foundation of my non-fiction work", she has written. "When I wrote Intercourse and Pornography: Men Possessing Women, I used my life in every decision I made. It was my compass." Her experience is there again, on the first page of her new book, Scapegoat, published today. Four paragraphs down she alludes to the "beating and torture I experienced in marriage some 30 years ago". It was this, she says, that made her abandon pacificism: "I finally got away not because I knew that he would kill me but because I thought I would kill him."

Only once, it seems, when Newsweek magazine asked that she either publish anonymously, or produce medical or police records to support an account of battery by her husband, has anyone questioned Dworkin's experience. She says she asked Newsweek "when the freedom of speech I kept hearing about was going to apply to me". The article subsequently came out in the Los Angeles Times. Doubt my argument, she challenges, and you doubt the torture of real women, you belittle the torture of me . Even her prose style is a kind of gauntlet, daring you to demur. "I was 10," she writes, "when we moved to the suburbs, which I experienced as being kidnapped by aliens and taken to a penal colony. I never forgave my parents or God . . ."

Often maddening on paper, Dworkin is, in real life, endearing and seemingly vulnerable. Most liberal interviewers, British ones at least, are apt to sympathise, and rarely question why Dworkin's story of rape and torture should be accepted as representative, privileged, for reasons of her seniority in both feminism and misery, over less dramatic personal histories. To argue with her would be not just impertinent, but akin to saying: "I don't give a toss about your tragic life."

This, possibly, explains the deafening silence - from the media, at least - which has followed Dworkin's latest autobiographical fragment: the account of her recent rape published in the New Statesman and in these pages last week. From fellow readers, I've heard about as wide a range of reactions you could get, from horror to bafflement, from pity to frank disbelief. For those who did not see the piece: Dworkin alleges that, last year, at the age of 52, she was drugged and raped in a hotel room by two men, whom she believes - no, knows - to have been the hotel's bartender and a serving boy.

In the New Statesman she was precise about the town, a European city, and the date (although to be pedantic, the date she supplied did not, as she said, fall on a Wednesday). All the police need, then, is the name of the hotel and the men can be questioned. But Dworkin has not been to the police. She came round from the assault to find a "big, strange bruise" on one breast and "huge deep gashes" on one leg which would not stop bleeding.

For some reason she did not call a doctor to staunch the bleeding; neither did she call hotel security nor the police. The reluctance of a rape victim to be further violated by examination and questioning is understood, but if this is what prevented Dworkin from seeking help it does not seem consistent with her current decision to relive the ordeal, in vivid detail, for readers of the New Statesman.

Reflecting on the easiness of this new form of assault, she writes: "You can do this hundreds of times with virtually no chance of getting caught . . ." Well, you can if women you have raped do not call a doctor when they wake up bruised and bleeding. Is this bartender, with his accomplice, to be allowed to continue drugging and raping female guests?

Dworkin says that her "feminist gynaecologist" (whom she called in New York) said "a gynaecological exam wouldn't prove anything one way or the other and that the call from me convinced her that she should have an unlisted phone number". No explanation is offered for this sudden outbreak of hostility.

In the same year as this rape, Dworkin's father died and she herself was seriously ill, becoming delirious. She writes, dreadfully: "I'm ready to die." Maybe, at this grim stage in her life, we should just leave her alone. But her rape claim, like any other, seems to deserve scrutiny before it takes its place in the archive against intercourse. It is Dworkin, after all, who, consistent with her vow, chooses to use this experience for "women's liberation", depicting it as part of a wave of "foolproof rape". Offered like this, as evidence, the article contains so many opacities, begs so many questions, that it reads almost as if Dworkin wants to be doubted.

Most people beginning the piece would expect to find in it, somewhere, facts to verify it. Instead, Dworkin supplies inconsistency ("gashes" become "scratches"), absence of evidence, lack of support. Even the love of her life, John, "looked for any other explanation than rape". Some of her readers will have done the same.

Several have suggested to me that if illness has left Dworkin dangerously overweight and unwieldy, delirious in the streets of New York, the same could have happened in her European hotel. Could she not have fallen and cut and bruised herself? Elsewhere, she has written that: "There is always a problem for a woman: being believed."

True, but this account does nothing to help itself. Sometimes the Gradgrind approach is right. Facts, that's what we need. A horse is a quadruped. Graminivorous. Forty teeth. And a rape either occurred, or it did not.

Scapegoat: Jews, Israel And Women's Liberation, by Andrea Dworkin, is published by Virago on June 8, priced £22.50.