This Common Knowledge guest column concerns performance, understood in its simple ur-sense of “doing things” in the world. It continues the author's analysis, in his book The Mangle of Practice (1995), of cultural evolution as a “dance of agency”: a performative, decentered, and emergent back-and-forth between a multiplicity of actors, variously human and nonhuman. The author's concern in this new essay is with apparently stable and dependable technologies, such as cars, computers, and power stations, which he conceptualizes here as “islands of stability” in the flux of becoming. On islands of stability, Cartesian dualism is simply true: humanity achieves command over entities that reliably serve our will. Still, while our worlds are built on them, their stability is not complete. To remain on islands of stability requires continual constructive work, and sometimes we fall off them anyway, with disastrous results, for stability is necessarily accompanied by performative excess. The performative analysis of islands of stability cuts humanity down to size and puts us in our place.