Contributed by Adam Simon / At a Four Walls event in Brooklyn in the early 1990s, Erik Oppenheim, at that time a young artist, stood up and said, “I’m starting an art movement. Anyone who wants to join, meet me in the back after the show.” It was a hilarious and audacious gesture, in part because no one joins an art movement on a whim, like a list-serve or an exercise class, but also because there hadn’t been any artist-initiated movements for a very long time. They proliferated in the late nineteenth and early twentieth century with the advent of Impressionism, Surrealism, Futurism, and Dada, and enjoyed something of a resurgence in the 1960s with Fluxus in the United States, Supports/Surfaces and Zero in Europe, and the Gutai Group in Japan. Most of what we consider movements were proclaimed by an outside observer, usually a critic or curator, looking to group artists who had similar concerns and made work that fit the designation. For the artists themselves to rally around a specific cause, even an aesthetic one, was not required.