WHEN dancer-choreographer Merce Cunningham, 57, appeared for a week at New York's Minskoff Theater recently - his first independent Broadway engagement ever - one might have supposed either that he had sold out to the Establishment, or that the Great White Way had suddenly gone avant-garde.

But in the Minskoff programs, mixing old and new works, one encountered the same constellation of traits that had marked Cunningham an artistic troublemaker almost three decades earlier - far-out musical scores by John Cage, David Tudor and other "experimental" composers, which seemed to have no logical relation to the dances they accompanied: eccentric costumes and decor by Robert Rauschenberg and Mark Lancaster; and movement that appeared typically kinky, disconnected and perverse by traditional dance standards.

Nor has Broadway yielded itself up to esthetic anarchy. Cunningham himself, and those who have followed similar paths in his wake, have been softening us up for years from the sidelines. Television, films and Broadway itself have felt his influence by a sort of cultural osmosis. At the same time, Cunningham innovations that looked sacrilegious when new have lost some of their iconoclastic sting.

Cunningham has continued to push forward in his way, but his successors have jettisoned his axioms and staked out new, more extreme territory. As someone put it recently, the future isn't what it used to be.

Nevertheless, as far as dance is concerned, the whole notion of an avant-garde started with Cunningham and he remains its chief public symbol.

If one scans the evolution of American dance in this century in the broadest terms, four main phases present themselves, each set in motion by a "revolution" of sorts. The first, during the intitial three decades, embraced the attempts by Isadora Duncan and the Denishawn school to forge dance anew from scratch, so to speak - to establish a legitimate, serious dance art to challenge the purposed fairyland frivolities of classical ballet.

The second, focused during hte '30s and '40s around Martha Graham, concerned the effort to found a specifically American, systematic dance esthetic that could cope with such subject matter as social protest, psychological disturbance, sexuality, or heroic tragedy.

Then, from out of the West in the mid-'40s, came Cunningham to lead the third revolution. It was Cunningham's great quest to assert the full autonomy of dance art, to "free" it from servitude to music, or storytelling, or psychology, or theatrics or anything else, and instead of glorify dance movement for its own sake.

Cunningham was well-equipped for the task. He knew what he was repudiating from the inside out, and what was worth preserving, too. He himself was from the start a superlative dancer and stage presence; he had been one of Graham's leading soloists and had bad intensive classical training at Balanchine's School of American Ballet.

From the early days, too, he surrounded himself with like-minded upstarts in other fields - there was a notable performance in 1948 at Black Mountain College, for instance, of Erik Satie's one-act lyric fantasy. "The Ruse of Medusa," which had dances by Cunningham, sets by Willem and Elaine de Kooning, props by Buckminster Fuller (among others), and direction, in part, by Arthur Penn (yes, the same of "Bonnie and Clyde").

Cunningham's association with John Cage began in the '30s, and later he was to collaborate with such other musical and artistic radicals as Christian Wolff, Earle Brown, Gordon Mumma, David Tudor, Morton Feldman, Andy Warhol, Frank Stella, Jasper Johns and Bruce Naumann.

Cunningham, more than any other single figure, gave the spur to contemporary multimedia performance. In perhaps his quintessential opus, "Variations V," first seen in New York in 1965, Cage furnished the music; Stan Vanderbeek did film projections; Nam June Paik created video imagery; and Billy Kluver and Robert Moog managed the electronic circuitry. And among other novelties that took place during the performance of this work, for the finale Cunningham himself rode across the stage on a bicycle, transporting a potted plant in its wire basket.

In a variety of ways, Cunningham has sought to divorce dance movement from specific narrative or emotional connotation. For this reason, his choreography has been called "non-linear" - it dispenses with the careful sequence of preparations and linkages that gave traditional modes of dance their sense of continuity and dramatic coherence.

Instead, Cunningham explores the expressive potential of unlikely juxtapositions, of non-sequiturs in movement. This is one reason for his much discussed use of chance procedures in determining the order or structure of a dance (by tossing coins or dice, for instance). Another is his desire to expand creative possibilities beyond the constraints of human habit or volition.

One of the most characteristic features of Cunningham'w work - in the captivating "Solo" of 1973 seen at the Minskoff, for instance - is his treating the body as if every portion of it had a mind of its own, eyes and neck and fingers and hips and ankles each marching to a different drummer. This aspect of his choreography gives so much of Cunningham's repertoire a playful or humorous tinge, though there is much that is deadly serious in tone as well.

However much Cunningham has extended the horizons of movement, it is still - to a very large extent - dance movement that he works with, that is to say, movement that requires a highly disciplined anatomy and draws its stylized shapes from an artist's imagination. It was left to the fourth revolution, the post-Cunningham revolution that brings up to today's frontier, to abandon this final restriction. In the works of choreographers like Ann Halprin, Meredith Monk, Twyla Tharp, Yvonne Rainer and others, one sees dance reaching out to the "found" movement of everyday life - to movement drawn from the street, the ballpark, the kitchen, the construction gang.

In the past few years, we seem to be seeing a reversion to "dancy" movement and other traditional post-Judson departures of the late '60s. Cunningham's work - old and new - now looks positively classical.

It is ture that Cunningham's body has lost much of its erstwhile speed, elasticity and attack, and fascinating as he still is to watch, he has difficulty answering his own choreographic demands these days. And the company, with its large complement of relative newcomers, lacks the distinctive rapport of earlier Cunningham entourages.

None of this, however, diminishes Cunningham's claim to place of high rank in the pantheon of American dance. In March, he will receive the 1977 Capezio Award, the closest equivalent to an Oscar in dance. The citation lauds him for having made us "think about dance in new ways and see dance with fresh eyes." It would be hard to propose higher praise for any dance artist.