<p>The challenge of articulating the society-nature interface in the context of the ecological crisis has been at the center of recent debates in environmental philosophy. While some insist on the necessity to develop robust ways of talking about natural processes as distinct from society, others propose to abandon the nature-society distinction as outdated. In this article, I argue that a critical-realist assessment of nature is a necessary starting point for post-capitalist ecopolitics. To prove this, I focus on Cornelius Castoriadis’s reflections on nature and material imagination, which have been overlooked in existing literature on this topic. At first, I offer an overview of current debates on the nature-society divide and argue that abandoning this distinction generates theoretical and political impasses. I then argue that Castoriadis’s account of biophysical processes as dynamic and self-determining provides an original critical-naturalist framework, which presents geophysical and biological phenomena as connected yet irreducible to the normativity of the social. Finally, I explore how this approach can direct ecopolitical projects, moving beyond Castoriadis’s narrow definition of degrowth and toward practices of commoning. I contend that different ways of sharing resources, infrastructures, and space disclose alternative ways of integrating the creativity of social imagination with the creativity of nature and thus reshaping the society-nature interface in the Anthropocene.</p>