Over the last decade, the Anthropocene has overrun the discourses of the humanities and social sciences. Remarkably, two of the most astute commentators, the cross-disciplinary theorist Barbara Herrnstein Smith and the unorthodox philosopher Isabelle Stengers, find inspiration for grappling with these issues in the same apparently odd place: the work of the Polish microbiologist and comparative epistemologist Ludwik Fleck. The first part of this essay explores the role of Fleck's radical constructivism in Smith's analyses of perplexing Anthropocene realities and Stengers's (...) arguments for slowing down science and learning to “compose with Gaia.” In conjunction, they generate a pattern of speculative, conceptual, practical, and political motifs for dealing with changing climates. The second half of the essay uses those insights to test a divergent series of proposals for how to conceive science, politics, theory, and environmental relations in the Anthropocene. (shrink)