The multidisciplinary artist Nayland Blake was once a child gazing in wonder at Alexander Calder's "circus" in the lobby of the Whitney Museum. "Who's the circus now?" Blake said the other day, some fifty years later, gesturing around a conference room across from the museum's education center. Blake, bearish, Merlin-bearded, soft-spoken in the manner of a blacksmith teaching kindergartners, was preparing for a session in their performance series, "Got an Art Problem?," part of this year's Whitney Biennial. In June, Blake threw a "Gender Discard Party" in the museum's lobby, to which guests were invited to "bring your own baggage" and dance away the woes of classification, in view of the artist's "Rear Entry," a reproduction of the door to the Mineshaft, the former gay club in the meatpacking district. Blake thought the curators would never go for "Rear Entry."