The equation is self-evident, like a standing ovation.
Broadway musicals equals theatrical escapism.
But what about the musical as social history? Or as a reflection of fluctuating moods and mores? Or as an embodiment of pop-cultural evolution?
Take the current scene, for example. The latest Broadway smash hit is the Michael Bennett-Tom Eyen-Henry Krieger spectacular, ''Dreamgirls.'' In the best show-business tradition, it has already conferred stardom on the youthful Jennifer Holliday. That's how legends are made. And that's the Broadway musical at one level.
But ''Dreamgirls'' strove to be more than what Cole Porter called ''another op'nin', another show.'' The plot centers around a singing trio and its conniving manager. Seeking for an image more acceptable to Las Vegas, New York, and TV moguls, the opportunistic manager recasts and rearranges the Supremes-like Dreams of the title. In a parallel bow to sleekness and assimilation, the story's earthy black soul singer is toned down and slicked up.
''Dreamgirls'' makes no pretensions to being a musical with a message. Its business is entertainment executed with breathtaking razzle-dazzle and showmanship. But in its time-sweep from the early 1960s to the early '70s, the show creates some striking vignettes of a decade in flux. Furthermore, in their footnotes to show-biz history, the authors spotlight the seamy side of talent exploitation, specifically as it affects black entertainers. The rise of these Dreams involves sharp deals and ruthless disloyalties, payoffs and payola, and the kinds of conniving that can go into the making and unmaking of stars.
''Dreamgirls'' is also about the American success dream. Early in the show, the theme is satirized in ''Cadillac Car,'' a mock-tribute to upward mobility. But flashy success doesn't necessarily buy artistic freedom. Later on in the story, arguing for her right to a proffered Hollywood break, the Dreams' lead singer tells their manipulative manager: ''Like any other American girl, I want to be a movie star.''
What else is ''Dreamgirls'' about? According to its director-choreographer, the show is about family. In a New York Times interview, Mr. Bennett elaborated: ''Family structure, with Taylor (the manager) being the father in a sense -- the good Daddy or the bad Daddy depending on the scene. I think the buttons I'm pushing are family buttons. Sister and brother are united and you feel good. You feel bad when you see something disintegrate that's represented as a family to you. I like material when it's very universal.''
By coincidence, Mr. Bennett's still current 1975 hit, ''A Chorus Line,'' represents yet another -- and a unique -- example of the Broadway musical as social phenomenon and force. Since it opened six-and-a-half years ago, this affectionate celebration of Broadway ''gypsies'' (the chorus dancers indispensable to big production numbers) has poured well over $10 million into the working capital of the nonprofit New York Shakespeare Festival, where the show originated. ''A Chorus Line'' has thus helped finance more than 100 festival productions plus seven seasons of free Shakespeare in Central Park. No other Broadway musical has performed such a funding role for a public service institution.
What more might be said about Broadway musicals as a socio-cultural phenomenon? Without getting too academic about it, let's categorize briefly:
Black artists. ''Ain't Misbehavin' '' honors Fats Waller, one of the bright blithe spirits of 20th-century musical Americana. Its general air of sassy joy makes the show's quietly sung ''Black and Blue'' the more deeply poignant. ''Sophisticated Ladies'' salutes with consummate pizzaz just one aspect of the great Duke Ellington's creativity. In the course of ''Lena Horne: the Lady and Her Music,'' the incomparable Miss Horne recalls - with sometimes ironic humor but without bitterness - the uses and abuses of a talented black woman in earlier Hollywood.
American folkways. Like previous shows inspired by comic strips, ''Annie'' brings to stage life the mythic cartoon characters so long and so intimately identified with the nation's pop culture. ''Barnum'' invites one and all to ''join the circus, be a kid again,'' while commemorating the legendary 19 th-century showman and founder of ''The Greatest Show on Earth.'' ''Sugar Babies'' enshrines three American institutions: Mickey Rooney, Ann Miller, and old-timey burlesque. ''42nd Street,'' the great Gower Champion's final legacy, resounds with the tap-tap-tapping of a hundred dancing feet in a gorgeous splurge of nostalgia recalling the movie musicals that delighted a whole generation of filmgoers.
Politics and ideology. The latest revival of ''Camelot'' inevitably recalled the aura of John F. Kennedy's brief presidency. ''Evita,'' superficial as it is, at least attempts a sardonic commentary on the central figures in one of Argentina's previous bouts with corrupt and ruthless dictatorship.
All this is not to endow the escape artistry of the Broadway musical and its show-biz sponsors with a social consciousness undreamed of in their box-office philosophy. And yet . . . it seemed worth pointing out that there may be some nuggets of gold in them thar frills.