When Pilobolus Dance Theatre made its bow in 1971, it seemed like an idea whose time had come. Today, nigh onto two decades later, the time has by no means run out, to judge by the near-capacity house for the group's appearance at the Warner Theatre Saturday night and the enthusiastic response. But the idea has been smudged almost beyond recognition, and expediency appears to have replaced artistic reconnaissance as a guiding principle.

Pilobolus was founded by Moses Pendleton and Jonathan Wolken, who were dance students of Alison Chase at Dartmouth at the time (Chase and Martha Clarke joined as the first women members in 1973). The kind of work they were doing in the troupe's early years could be seen in Saturday night's "Ciona," dating from 1974. "Ciona" is an abstraction danced in unitards, in which the performers form odd and amusing body linkages, assemble into human pyramids, swing each other out into living carrousels and do broad jumps from squat positions like a platoon of frogs.

"Ciona," choreographed by the above foursome and two other Pilobolus veterans, Robby Barnett and Michael Tracy, is a memento of the refreshing originality of the troupe's start, and of its major achievements as well. Collective choreography was one of the ensemble's trademarks, and living and working outside the New York establishment was another (the company is still based in Washington, Conn.). With these armaments against convention, the group forged a genuinely new, hybrid art form, falling between the cracks separating dance, gymnastics, mime and theater.

Some other elements gradually added into the mix were evident in Chase's 1978 solo "Moonblind," as performed at the Warner by Carol Parker. Grotesquerie, anatomical contortion and a somewhat morbid eroticism are conspicuous features here, as they were in subsequent Pilobolus creations.

Since then, however, the idiosyncratic domain the troupe created has become more of a difference without much distinction, and the collective aspect of the inventive process has evolved into a parody of itself. Five of "Ciona's" choreographers are now listed as artistic directors (Clarke left to pursue her own work in 1978), and with Tracy's retirement from performance last year, none of them dances any longer. The current complement of six dancers -- Parker, Jack Arnold, Jim Blanc, Austin Hartel, Peter Pucci and Jude Sante -- also takes a hand in making new work. Thus one ends up with a piece like the finale of the Warner program -- "I'm Left, You're Right, She's Gone" -- which has four directors, six performers and no fewer than 10 choreographers. Under such circumstances, the work's slapdash construction -- not untypical of Pilobolus -- would seem unavoidable.

Since the early years, Pilobolus has firmly established its own turf and following, and amassed worldwide renown. Saturday night's program averted the neo-Gothic rut of some previous seasons, in which every performer looked like a cousin of Quasimodo, and every work a macabre orgy. But the recent works veered either toward superficial illusionism and titillation -- as in "Land's Edge," a spooky variation on the theme of the rejected outsider eventually assimilated into an alien society -- or outright opportunism -- as in "I'm Left," which uses Elvis Presley recordings as a scaffold for a warmed-over version of "Grease," highlighted by bubble gum, bobby socks, "falsies" and kicks to the groin. And though the troupe's present dancers are attractive and superbly skilled, they don't project the vividly perverse personalities that made Pilobolus' originators memorable even when the choreography was more trick than treat. Always controversial, Pilobolus today is more of a paradox than ever.