THE GOOD APPRENTICE. By Iris Murdoch. Viking. 522 pp. $18.95.izabeth Ward

CAN A MAN be absolutely truthful?" asks a psychiatrist in Iris Murdoch's new novel; he then goes on to reflect, "These are problems most people solve by instinct, usually wrongly, without even noticing." The Good Apprentice, vintage Murdoch as it is, seeks to force us to notice such problems, to confront the mysteries of "life and death, good and evil," to worry away at the question of "what's fundamental." For those who have developed over the years a taste for Iris Murdoch's black, cerebral, unsettling novels, The Good Apprentice will be a welcome dose of a familiar formula. For those who prefer to distinguish a little more sharply between their fiction and their moral philosophy, it may appear, like much of her previous work, long-winded and overly analytical. As somebody in the novel observes, "Not everything is improved and clarified by being dug up." Either way, though, this is not a work to be taken lightly.

Character is all in Murdoch, but plot is crucial, since her revelations of character depend so heavily upon the Victorian devices of coincidence and surprise. The Good Apprentice is not quite as tightly or cleverly plotted as usual, but its coils are still sufficiently intricate to set the reader flipping back and forth to double-check impressions and get his facts straight (even though in the fictional world of Iris Murdoch there is really no such thing as a fact).

The central character is young, earnest, brightish Edward Baltram who, as the novel opens, tricks his best friend into taking a drug, leaves him asleep, then returns to find that his friend has jumped out of the window and killed himself. Stricken with guilt and grief, Edward flees London for the symbolic fen country (flooded and in sight of the sea) in search of his real father, forgiveness and enlightenment. This remarkable parent, Jesse Baltram, is or was an artist, notorious womanizer and erstwhile guru who has established one of those rural, pseudo-monastic, artistic households with which England abounded in the first half of this century. Here at Seegard, since nothing is what it seems, Edward finds not the spiritual relief he hoped for but "a sudden quick glimpse of insanity and death", and is pushed further into the "black dark" which haunts him. Taking him back and forth between London and Seegard, Edward's sojourn of spiritual rehabilitation -- really a quest for self-knowledge -- supplies the novel's basic storyline.

Besides Edward, the most important character in the book is Edward's half-brother, Stuart, the "good apprentice" of the title and in some ways the book's moral touchstone, although his authority is typically undercut by Murdoch's penchant for the devastating physical detail. "Stuart . . . had a large pale face, pretty lips and blond hair. . . . His eyes were a light amber brown, almost yellow, like the eyes of an animal. Someone had once likened Stuart to a plump white grub with a big head emerging from an apple, but the image was unjust." Stuart has just given up a promising career in mathematics in order to devote his life to becoming good; he is "apprenticed to goodness -- a rather special case." He is not sure what practical form this should take and is subjected to a good deal of ridicule, but he gets most of the novel's best lines and emerges at book's end possibly less compromised than anyone.

The rest of the large cast of characters, nearly all of whom are related to one another in various complicated ways, represent subtly graded points along the moral spectrum between the clear-headedness of Stuart and the murky naturism of Seegard's inhabitants. Of these, by far the most interesting is Edward's uncle and psychiatrist, Thomas McCaskerville, a Scots Jew and humanist, who lives by the realization that "life is an image of death. It is a study of dying." In fact, Thomas may come closest of all to voicing Iris Murdoch's own deepest convictions and the novel's rather grim essence: "We practise dying through a continual destruction of our self-images, inspired not by the self-hatred which seems to be within, but by the truth that seems to be without; such suffering is normal, it goes on all the time, it must go on."

A continual destruction of self-images: this is actually an apt description of Iris Murdoch's literary technique. Edward's case of spiritual affliction is both particular and extreme, but it is also surely to be understood as representative, to a profound degree, of a more general contemporary malaise. He "felt sick with a pointlessness and loneliness which deprived him of his sense of himself. He felt a fright at not existing, a feeling of the entire precarious nature of identity." Taking this feeling as a premise, The Good Apprentice proceeds to demonstrate that nobody's identity is stable and that there are no moral certainties; as Stuart's father surmises, "what's fundamental could be evil, or chaos."

So we are subjected to the usual series of exposures and revelations. Seegard, that retreat of simple living, turns out to be also a place of tyranny and malice; Jesse Baltram is no longer a spiritual father-figure and sex hero but a senile old man, imprisoned by his wife; Thomas McCaskerville's wife is having an astonishing clandestine affair with Stuart's father, Harry; one of the cloistered daughters of Seegard becomes a Soho stripper; the girl Edward desperately wants to marry has been in love with an old friend all along, and so on. It is a marvel that any version of peace at all is achieved, as it is, by the end of the book. Some characters get what they want and some don't, but Edward and Stuart and Harry are at least able to drink a champagne toast to Edward's discovery, "'Oh well, there are good things in the world' . . . 'But which things are they? We might all mean different ones.' 'Never mind, drink to them. Come.'"

Any three reviewers might well agree to pledge the same toast to The Good Apprentice itself.