Context is everything. Or if not everything, a lot.

If "The Floating Lightbulb" were a play by someone less exalted than Woody Allen, and if it had been produced on less hallowed ground than that of New York's Lincoln Center for the Performing Arts, it would certainly have met a more enthusiastic reception. It might have been hailed as a roughly fashioned but wildly funny and unsettling comedy -- rather than flailed as one of the Broadway season's resounding disappointments.

Set in Brooklyn in the evocative year 1845, the play suffers from the extra liability of being easy to lump into the broad category of semi-autobiographical comedies about childhood trauma. But what a childhood! And what trauma! The central character, Paul Pollack, is a socially crippled teen-ager who steers as clear of school as he can despite an IQ of 148, and who suffers from a debilitating stutter.Every step he takes, every word he utters, is a painful exertion. Yet he dreams of being a magician, performs wonderful tricks in the privacy of his bedroom, and regularly extricates himself from encounters with his mother on the excuse that "I've got to practice."

His father, Max, is a numbers runner who is planning to abandon his status as henpecked husband for a Florida retirement with his girlfriend. So he has a minimum of contact with his children. But when he's on the premises, he finds Paul an embarrassment. "You don't have friends," he says. "You don't play ball. You don't like sports." His prescription is for Paul to "act a little normal once in a while."

Paul's mother, on the other hand, is an overwhelming, omnipresent, hyperactive figure. Think of Beatrice Arthur and you'll have a capsule idea of Enid Pollack -- especially since, as it happens, Arthur plays the part. Ridiculing Paul's preoccupation with magic, she tells him: "It's what we need around here -- more tricks and illusions. Learn to saw a woman in half. You can practice on me." But she reassures him that he's a good-looking boy and a "genius," and when she meets a theatrical manager, she promptly arranges an informal audition for Paul -- to take place in their living room when the manager comes for a visit.

Paul is frightened to death. "You're as ready as you'll ever be," she tells him.

It's a ludicrous but harrowingly comic family situation, and a young actor named Brian Backer makes Paul one of the most poignant nervous wrecks you'll ever see. Standing around with his hands held together between his legs, he looks like the classic nebbish until, when the slighest demand is made of him, he goes to pieces. Tiny Tim (the musician, that is, not the Dickens character) might have cut such a figure as an adolescent.

The general dismissal of the play as a minor effort shows how much we take for granted in the theater, especially where comedy is concerned. All the intra-family relationships have been etched out precisely and believably. The mother has wonderful comic lines; when a friend describes herself as a "dried-up well," for example, Arthur replies: "Yes, only the other day I was saying that you were a dried-up well." And the second act brings a marvelous encounter between Arthur and Jack Weston as the manager, who strives to contain his atonishment while the boy-magician, getting his big break, keeps flubbing his tricks and rushing to the bathroom to vomit.

The central matter of "The Floating Lightbulb" is the relationship between mother and son, and their curtailed lives, subsumed in pretense and fakery. (The play has been compared to "The Glass Menagerie," with Paul filling in for Laura and the manager for the gentleman caller.) Unfortunately, loose ends hang from the play like slashed life-support lines from a patient murdered in the intensive-care ward. The romance that develops between Arthur and Weston seriously confuses the direction of Allen's story, without ever making us see the mother as much more than the selfish poseur of the opening scenes (a difficulty exacerbated by Arthur's strong ties -- in her mind and ours -- to the Amazon character she has portrayed on the TV show "Maude" and elsewhere).

The father's extramarital romance, on the other hand, is told in such brief fragments that the playwright might as well not have bothered. And despite a strong performance by Danny Aiello, the father's role is the least original and least satisfying characterization in the play.

For all its faults, "The Floating Lightbulb" surely represents an honorable and intriguing windup to the Vivian Beaumont Theater's first season under Richmond Crinkley and his six-headed directorate -- Woody Allen, Edward Albee, Sarah Caldwell, Liviu Ciulei, Robin Phillips and Ellis Rabb. I missed the reputed disaster of the season -- Caldwell's staging of "Macbeth" with Philip Anglim starring -- but "The Floatng Lightbulb" and the Rabb-directed "Philadelphia Story," with memorable performances by Blythe Danner and Edward Herrmann, seem to me to add up to a fair half-year's work.

And now comes the news that the Beaumont will be dark again next season, as it was for three years after Joseph Papp tossed in the towel in 1977. Lincoln Center has received an $8 million gift for acoustical and archectural adjustments, and work on the Beaumont will prelude a second season. Crinkley (who founded the Folger Theater Group and co-produced the Kennedy Center's bicentennial season before setting up shop as a Broadway producer) says he hopes to be back in 1982-83.

No one can dispute the grotesquely unfriendly shape and size of the Beaumont, but the expense and timing of the renovation boggle the mind. (The donors the Fan Fox and Leslie R. Samuels Foundations, were prepared to give $12 million until the powers at Lincoln Center balked at renaming one of their theaters the "Fan F. Samuels Theater.") Now all the effort to reestablish an identity and an audience for theater at this nationally conspicuous location will be chucked out the window once again. Where else but in the world of non-profit, quasi-government enterprise would such madness be tolerated?