"Man, Woman and Child" should ease the mind of anyone who feared that Erich Segal might have improved after all these years. Hey, not to worry! The Knight of the Mournful Pen is still dreaming up (or self-projecting) the most excruciating, emasculated protagonists in contemporary Weepie Lit, and they're still taking it on the chin from womenfolk whom Segal is pleased to imagine as vastly superior in glibness and moral character.

Needless to say, his awestruck conception of women is as grossly sentimentalized and cliche'd as his poor-dears conception of men, but the imbalance makes it easier for actresses to get the upper hand, as Blythe Danner frequently demonstrates to the helpless chagrin of Martin Sheen in the dreary course of "M, W & C," now showing at several area charitable institutions.

It seems a little rash of Segal and his madly faithful directing accomplice, Dick Richards, to chime in with another revolting account of guilt-racked paternity so soon after the mal de mer of "Table for Five." Not only would the Segal opus make an ideal companion feature for "Table for Five," it would be better served by the title "Table for Five." Segal borrows from Sloan Wilson's "The Man in the Gray Flannel Suit" for his odd guest out, a princely little French boy named Jean-Claude whom the hero, Sheen as a college English prof named Bob Beckwith, has discovered to be his illegitimate son, conceived without his knowledge years earlier during a brief European encounter with a provincial doctor named Nicole.

News arrives from a mutual friend that Nicole, an independent sort who never married, has died in an auto accident, leaving Jean-Claude orphaned. After some obligatory picturesque brooding, Bob unburdens himself to wife Sheila, a devoted class act who has borne two precocious treasures named Jessica and Paula ("Oh, daddy, don't be punctilious!" erudite Jessica is apt to scold), edits books for the university press and may have a little socked away, since the Beckwiths seem to live in surroundings that would turn the richest alumni green with envy.

"I just wish I could make this up to you," Sheen mutters into his profly whiskers, allowing Danner to put him in the Deepfreeze with an ironic retort, "I don't think you can." Segal can't seem to get enough of this sort of masochistic discomfort, so Sheen takes a more presumptuous rhetorical approach--"You aren't gonna let this shatter our relationship, are you?"--and gets frosted again by Danner's curt "I don't know."

There's no denying that this abasement ritual has its entertaining aspects, what with Sheen acting like an incorrigible slug and Danner blithely augmenting her cynical replies with a glittering display of lip-licking, head-bobbing, tongue-in-cheek positioning and other expressive facial semaphore. The upshot of the confession is that Bob proposes to bring the orphan over for an Easter vacation visit, a guilt-assauging gesture that supposedly drives Sheila to the brink of adultery or panic, fearing that (1) People Will Know or (2) the boyish interloper will disrupt their idyllic home.

As a matter of fact, Sheila keeps using the word "perfect" to describe her marriage before the past caught up with imperfect Bob. Segal may be one of the last educated persons on Earth who still finds it appropriate to blubber about abstractions as fundamentally ridiculous and unattainable as "the perfect marriage." No one outside the willfully naive confines of heartache fiction would dare to take such a term seriously or even desire the cosmetic, placid sort of relationship it implies.

Segal hasn't the foggiest notion of what to do with this stale marital crisis pretext except moon around the house with it. There's never any problem worth a second's sincere anxiety. Sheila's alleged hostility to the Little Prince is never really reflected in Blythe Danner's playing, which seems naturally sympathetic and maternal. The juvenile actor cast as Jean-Claude looks rather more like Danner than the girls cast as her daughters. The kid himself causes no difficulties and even goes out of his way to exonerate Bob for whatever neglect he's been guilty of, which is precious little under Segal's poorly contrived cirumstances.

On the other hand, there's no reason to forgive either Segal or Sheen for wallowing in the sort of comforting lines that Bob actually uses on the boy: "Jean-Claude, you just suffered a very great loss and you're feeling a very deep pain . . ." I don't know about Jean-Claude, but Segal is always inducing a very deep pain in the ear by having characters talk in this hideous, inhuman fashion. Moreover, who needs another inferior tearjerker designed to stroke the overcompensating self-pity of a daddy with a bad conscience? These recurrent attempts to jump on the Kramer bandwagon had degenerated into a bad joke six months after "Kramer vs. Kramer" was released, but we're still watching latecomers like Al Pacino and Jon Voight and now Martin Sheen struggle to catch up with a sentimental gimmick that was highly suspect even when it worked.

Segal's detachment from reality does set up some blissfully funny gaucherie, like the faculty hostess who greets Bob and Sheila at her dinner party with the line, uttered in apparent sincerity, "Do you think we'd start without our best and our brightest?" The magic moment of conception between Bob and Nicole is also one for the funny books, since it appears to occur while they're standing waist-high in a far from secluded and probably polluted body of salt water. Everything considered, little Jean-Claude is a powerful argument for the miracle of life. MAN, WOMAN AND CHILD

Directed by Dick Richards; screenplay by Erich Segal and David Z. Goodman, based on the novel by Erich Segal; director of photography, Richard H. Kline, A.S.C.; edited by David Bretherton, A.C.E.; production designer, Dean Edward Mitzner; music composed and conducted by Georges Delerue; produced by Elmo Williams and Elliott Kastner for Gaylord Production Company. This film is rated PG. THE CAST Bob Beck with Martin Sheen, Sheila Beck with Blythe Danner, Bernie Ackerman Craig T. Nelson Gavin Wilson David Hemmings