In the ivory tower today, the idea that marriage is good is apparently considered an extremist notion. On the other hand, the idea that there are few real differences between normal men and convicted rapists is regarded as cutting-edge theory. That, at least, seems to be the conclusion of Harvard University Press, which recently, and under highly unusual circumstances, rejected an important new book on the benefits of marriage.

The book -- The Case for Marriage: Why Married People Are Happier, Healthier, and Better Off Financially -- is by Linda Waite and Maggie Gallagher, and has just been published, to considerable fanfare, by Doubleday. It was expected, until a few months ago, to be published by Harvard University Press. It dropped the book, however, and therein hangs a tale, one of political correctness run riot.

At a press like Harvard, a manuscript is reviewed by two scholars. If the reviews are positive, the book is slated for publication, pending final approval by the board, which is normally a formality. But with The Case for Marriage, the press's Board of Syndics stepped in to kill the book because -- according to the anonymous board critique -- its tone was too strong and its evidence too meager.

To anyone who compares The Case for Marriage with other books Harvard has proudly published, this is hard to swallow. Although the book is certainly a direct assault on several cherished feminist myths, its tone is measured. Whether arguing that staying married is better for children, or that husbands don't damage their wives' mental health, Ms. Waite and Ms. Gallagher write clearly, and calmly, and let their evidence speak for itself.

So how was such a work, hailed as "the most important book in the family field that has been published in many years" by one of Harvard's own internal scholarly reviewers, rejected at the last minute? It's hard not to suspect politics at play here, especially considering the tone of other books to which the Harvard board was pleased to give its imprimatur.

After all, Harvard has published no less than four books by Catharine MacKinnon, the radical feminist, whose core argument is that male sexual desire is a close cousin of rape -- whether women consent to sex or not. Reviewing her last Harvard Press book, Walter Berns, the political theorist, remarked that Ms. MacKinnon's argument expresses a thoroughgoing hatred of men. If scholarly tone is the issue, compare Ms. MacKinnon's rhetoric on sex to Ms. Waite and Ms. Gallagher's:

Ms. MacKinnon: "What in the liberal view looks like love and romance looks a lot like hatred and torture to the feminist."

Ms. Waite and Ms. Gallagher: "What these prominent researchers found may shock you: Married people have both more and better sex than singles do. . . . The answer, both theory and evidence suggest, is that the secret ingredient marriage adds is commitment."

Let's examine the charge of weak evidence. The press board seized upon the failure of Ms. Waite and Ms. Gallagher to prove causal connections, rather than mere correlations. But virtually no sociological study can do that. Proof that marriage increases a man's earning power would require the random assignment of a group of men to marriage and bachelorhood, and then a calculation of their earnings. In a review, the social scientist James Q. Wilson concluded that, despite the impossibility of running controlled experiments with human beings, Ms. Waite and Ms. Gallagher's evidence strongly suggests the benefits of marriage are real.

Ms. MacKinnon, for her part, has been criticized by such legal luminaries as Richard Posner for the thin evidentiary basis of her sweeping claim that pornography leads to violence. "There is no evidence that pornography does no harm," she writes, reduced to lurching for the double negative for support. Frustrated when an experiment shows convicted rapists and normal men respond to pornography in similar ways, Ms. MacKinnon argues that controlled experiments are useless because most normal men are undetected or latent rapists anyway. Would you accept that assertion, while finding Ms. Waite and Ms. Gallagher guilty of not proving causal relationships?

Besides Ms. MacKinnon, Harvard has published many deeply controversial books on sexual issues. In his book Homos, for example, the literary theorist Leo Bersani explores gay sadomasochism and pederasty. Mr. Bersani's point is that homosexuality, by its very nature, disrupts society -- and that this is a good thing. The only books Harvard seems not to publish are those critical of feminism. Is that why Harvard's board turned down The Case for Marriage?

I asked Mary Ann Glendon, a Harvard law professor and past member of the Board of Syndics, how unusual it was for the board to kill a book in this way. Careful to acknowledge that she had no official statistics, she said that she couldn't recall a single instance of rejection by the board in her nearly five years of service. If there were problems, said Ms. Glendon, the book was simply referred back to the author for revisions.

Although Press spokesman Mary-Kate Maco maintained that "books are turned down at all stages," she acknowledged that "it is rare for a book to be rejected at [this] level." The press refused to release a list of board members, declining further comment on grounds of confidentiality.

What could Harvard's real objections to The Case for Marriage possibly be? The early response by elite feminist reviewers may be suggestive. Slate's Katha Pollit panned the book absurdly as a "clip job." And in the New York Times Book Review, Margaret Talbot took only a single short paragraph to dismiss the book as mere "anti-divorce polemics."

Nothing could be further from the truth. The Case for Marriage is packed with scholarly evidence. The book enrages orthodox feminists because of what it says -- that marriage matters -- and not the way it says it. The tragedy is that efforts to suppress this book have been made, not simply by popular polemicists, but by America's foremost university -- Harvard -- an institution designed to sustain open and honest debate.