This article argues that scientific practice of all kinds does not simply represent but actively constructs social and cultural realities: it is involved in an "ontological politics." It reflects on activist research and addresses the question of how science, and especially anthropology, can contribute to bringing degrowth alternatives into being. We suggest that to overcome growth society and build a new imaginary, we first need to denaturalize and decenter basic concepts of modern ontology. We then show how and why activist researchers in new social movements such as degrowth are involved in bringing about new concepts, imaginaries, and practices. Drawing on our experiences as activist researchers, we propose some basic strategies and tools for activist research, including deconstruction, and the creation and/or use of new concepts, such as translation and weaving.