Art and politics, for many writers, don't mix. But that wasn't the case at the National Conference of Afro-American Writers, where the exception was the writer who did not discuss politics, in this case sexual and racial.

The fourth annual conference, sponsored by Howard University's Institute for the Arts and Humanities, opened Thursday and closed Saturday on the provocative note of black male-female relations and feminism.

Using the conference theme, "The Impact of the '60s Through the Prism of the Present," novelists, poets and critics pondered the social and political future of blacks in this country.

Keynote speaker Nathan Hare, a former sociology professor at Howard and now a clinical psychologist in Oakland, Calif, said that the "bourgeois white women's movement" was threatening unity between the black male and female.

Hare, 44, said the white woman's way to liberation was simple: "She has only to raise herself to the level of her man. If the black woman moves up and the black man does not move up accordingly, the plight of the black woman is intensified and she will . . . look around to find that she is even move isolated and alienated from her man . . ."

The psychologist said that as the white female has entered the labor force the black male has been pushed out "with obcious consequences to black sexual and family relationships."

In an interview, the psychologist said he because interested in black male-female relations because "everywhere I went people were crying the blues. Black women say they have no strong black men to stand beside them. On top to this, white women don't have enough white men to go around. So they are moving over to deplete the vanishing black male supply."

The conference reached its most heated moments at the closing session when feminist-lesbian advocate Barbara Smith spoke. She opened by saying the invitation to speak at the conference was the first request she had had to speak to a black group.

Then Smith, a fellow at the W.E.B. DuBois Institute at Harvard, went on to accuse black and white male writers of not understanding the black feminist perspective.

Speaking extemporaneously and reading from notes and her essay, "Toward a Black Feminist Criticism," Smith said, "There is no political movement to give power or support to those who want to examine black women's experience through studying our history, literature and culture. . . . When black women's books are dealt with at all, it is usually in the context of black literature, which largely ignores the implications of sexual politics."

Smith, who is in her 20s, said hite women examining black women's works are not equipped to deal with the nuances of racial politics.

She closed b appealing to her mixed black and white audience to examine all its thoughts about feminine culture. "I want to encourage in white women, as a first step, a sane account-ability to all the women who write and live on this sooil. I want most of all for black women and black lesbians somehow not to be so alone."

Though Smith's presentation was greeted by prolonged applause, many in the audience raised questions about how far her feminist-lesbian position could be taken. This reservation was perhaps best summed up by psychiatrist Frances Cress Welsing's comment that "an endorsement of homesexuality means the death of the race."

At a panel on ideology and esthetics, historian John Henrick Clarke warned that many young black writers are moving toward leftist politics. "Racism does not stop at the door of communism and socialism," he said.

In a discussion on publishing and book stores, Charles Harris, executive director of the Howard University Press, said black writers should write about subjects outside black topics.

"There is no reason why Afro-American writers can't write about the pathology of racism in the white family," he explained. "There is no reason why Afro-American writers can't write about the Arab-Israeli conflict."