Harp Harpy and Her Brood : THE OTHER SIDE <i> by Mary Gordon (Viking: $19.95; 385 pp.) </i>

Mary Gordon excavates four generations of a tormented Irish-American family in her new novel, and expounds upon them with a brilliance borne down by insistence.

Gordon is a hostess who introduces people to us by telling us all about them. The introduction once made, she keeps on telling us about them. They hardly speak for themselves. Her rendering of Ellen and Vince McNamara, their two surviving children, five grandchildren and two of their great-grandchildren, and their mutual pain, anger and mutilation, is full of splendid detail. But at the end, we have not so much met them as heard about them.

It is as if the act of fiction were the act of judgment. With corrosive wit and a touch of horror, the McNamaras are bound into their places. Part of the target effect is produced by the fact that virtually all of the important things in the book are told in retrospect.

Gordon’s theme is the darkness of the Irish-American soul--rarely has it been portrayed so darkly. To etch her theme more deeply, she dances her coruscating descriptions and observations around figures immobilized by their histories. Fiction is a balance between “How have we got here?” and “Where do we go from here?” Gordon’s stress is all on the former.

The past is not prologue but pretty much the whole thing. The present, at best, is an epilogue. The “today” in “The Other Side” floats upon 90 years of the McNamara story like a cobweb on a peat bog.

“Today” tells of the preparations of the silently feuding family to welcome Vince back from the cheerful hospice where he had gone with a broken hip, to the house where Ellen lies raving and cursing and dying.

When they were young, Vince had promised his wife that she would die in her own bed. He had tended her faithfully, as an incontinent and hallucinating invalid, until the night when she knocked him down and fled into the street in her nightgown.

Was this devastating blow--the source of the broken hip--the distillation of Ellen’s life of irascibility? Is the meaning of her fiery temper, her domination of the gentle, creative Vince, really nothing more than hatred? Will he, who has felt happy and free in the hospice, in fact go home? And is his family’s welcome really a demand that he reassume his place as the 90-year-old paterfamilias of a legacy of anger, frustration and resentment?

Brief sections describing moving day--Vince’s hesitant packing and doubts at the hospice, the tensions among the family waiting at the house in Queens--recur throughout the novel. They are barely jumping-off points for telling about the lives of the four generations of McNamaras.

Ellen fled to America at 16, after her father, a village pub-owner and store-keeper, placed his invalid wife in a country cottage and set up a mistress to live with him in town. Ellen’s anger never left her. When she was young, it gave her spark and allure. A rebel and a beauty, she enthralled Vince, and kept an intransigent vitality going in their home.

Vince is an artisan, a signal repairman on the New York subways and, later, a maker ofscaffold models for builders. Ellen’s fieriness, her fractious independence light his life for a while; as they grow older, they become a destructive burden.

For Gordon, Ellen’s angry spirit, inspiring and deadly at the same time, is the sign of the Irish-American heritage. It quite burns out the lives and spirits of her children. Magdalene, who runs a successful hairdressing business for a while, becomes an alcoholic, self-indulgent invalid. Theresa is a cold, hate-filled religious fanatic.

In the next generation, the results are mixed. Cam, a lawyer, inherits some of her grandmother’s intransigence, makes a dreadful marriage with a remote, inhibited engineer, and flowers through a native critical spirit and a love affair with Irv Silberberg, a kind and loving Jew. Dan, her cousin and law partner, has something of the gentle Vince in him; his life is messy but his spirit shines.

Other grandchildren include Sheilah, a prissy and unlikable former nun married to a former priest; John, erratic and violent, and Marilyn, a good-hearted nurse with three bad marriages.

Gordon’s vision of the Irish-American curse is a familiar one. She evokes a penitential self-denial, a religious constriction--which shows itself quite as strongly in the anticlerical Ellen--and an anger that produces monsters among those who wield it and guilt among those who resist. Hearing Irv speak nostalgically of the cheap summer resorts built in the Catskills for working-class Jews, Cam--a resister--asks plaintively: “Why didn’t the Irish have pleasant ideas?”

The author is best when she is lightest: dealing with those who manage to sidestep the curse--Cam and Dan--although with all kinds of appealingly neurotic side effects. Vince, an innocent, and an artist in his devotion to his craft, also sidesteps it to an extent. That he even contemplates staying at the hospice while four McNamara generations wait for him in Queens is at least a partial liberation.

With Ellen, the protagonist, and her two doom-bearing daughters, Gordon works too hard, too insistently. They are overwritten to the point where sometimes they seem to disappear. Gordon recites her feelings about Ellen, Magdalene and Theresa with such vehemence that there is not much room for the reader to acquire some.