BOOK REVIEW / NONFICTION : Why Human Rights Is the Real Issue in Fight for Gay Rights : A MORE PERFECT UNION; Why Straight America Must Stand Up for Gay Rights <i> by Richard D. Mohr</i> ; Beacon Press; $15, 140 pages

“A More Perfect Union” is specifically addressed to heterosexual readers. “Why Straight Americans Must Stand Up for Gay Rights” is the book’s provocative subtitle, and it is more correctly described as a book about human rights than “gay rights,” a term the author himself uses.

“As an invisible minority, gay men and lesbians also need civil rights protections,” argues Richard D. Mohr, “in order for them to have reasonably guaranteed access to an array of fundamental rights which virtually everyone would agree are supposed to pertain equally to all persons.”

Homophobia, Mohr asserts, is merely another expression of the same ugly bias that is sometimes directed at Jews, African Americans or Latinos. And gay bashing is “a form of vigilantism that bears a striking resemblance to the lynching of black men.”

Thus defined, gay rights is part of the civil rights movement in America, a movement that is entitled to the support of blacks, Jews, Latinos and every minority that has known the sting of hatred, violence and discrimination.

Mohr, a professor of philosophy at the University of Illinois, gives us an all-embracing manifesto that starts out as an essay on the philosophical and jurisprudential underpinnings of civil liberty and quickly escalates into an unrestrained call to arms for gays and straights alike in the name of “gay justice.”

Mohr is blunt and unsparing in his arguments in favor of gay rights. While he is hardly an in-your-face activist--and even though his prose is always courtly and well-considered--Mohr is not the least bit shy about demanding that gay men and lesbians be afforded the freedom to pursue their own vision of life, liberty and the pursuit of happiness.

For example, Mohr condemns the closing of gay bathhouses as a prophylactic against the spread of AIDS precisely because, as he puts it, such meeting places are so important to a sense of community and identity among gay men.

“With some slight exceptions like the gay choral movement, gay political organizations, and . . . . AIDS support groups, sex is the only mode in which gays in current culture are allowed to identify themselves to themselves,” he writes. “Self-respect, such as it is, for gay men in our culture is often the product of a robust sex life.”

Similarly, Mohr devotes a good deal of his book to the suggestion that “committed gay relationships” ought to be recognized as legal marriages. He argues that “gay life, like black culture, might even provide models and materials for rethinking and improving family life.” And then he makes the startling proposition that “a commitment to monogamy” is one condition of marriage that is not necessarily an element of gay marriage.

The central argument in “A More Perfect Union” is rooted in the constitutional right of privacy--the same concept that is the basis for the right of women to seek an abortion. As Mohr reads the right to privacy, it assures all Americans, men and women, gay or straight, the freedom to express themselves through their sexual identity without fear of a law against abortion or a law against sodomy. Even the threat of AIDS, he seems to argue, is no reason to abridge the right of sexual freedom.

“If independence--the permission to guide one’s life by one’s own lights to an extent compatible with the like ability on the part of others--is, as it is, a major value, one cannot respect that value while preventing people from putting themselves at risk through voluntary associations.”

Again and again, Mohr draws intriguing linkages between sexuality and politics. Mohr depicts “coming out” as not merely a moment of self-discovery and self-revelation, for example, but also an overtly revolutionary gesture.

“Far from signaling immorality,” he writes, “coming out to others affords one of the few remaining opportunities in ever more bureaucratic, technological and socialist societies to manifest courage.”

How does the advocacy of gay rights work to the benefit of “straight America”? Mohr holds out the bland promise of a better world for all of us if only we can acknowledge that gay men and women are entitled to genuine civil liberties and not merely the back-to-the-closet policy of “Don’t ask, don’t tell.”

“Society would be richer for acknowledging another aspect of human diversity,” he exhorts. “Families with gay members would develop relations based on truth and trust rather than lies and fear. And the heterosexual majority would be better off for knowing that they are no longer trampling their gay friends and neighbors.”

Still, Mohr does not quite deliver on the straightforward promise of his subtitle--he tells us why we should stand up for gay rights, but not why we must do so. To a reader who is not already convinced, the distinction may turn out to be crucial.