In this paper, we provide a general characterization of closure as a distinctive causal regime of autonomous systems, which cannot be reduced to physico-chemical causation without loosing relevant information about the system’s organization. Our argument consists in three steps. First, we put forward an account of how different levels of causation can be realized within a biological autonomous systems, by making a conceptual and formal distinction, based on the idea of symmetry, between processes and constraints exerted on these processes. Second, we develop the notion of dependence among constraints and, third, we claim that closure is realized as a mutual dependence among a set of entities having the status of constraints within the system. The paper might then make a relevant contribution to the elaboration of a conceptual and formal theory of closure, able to overcome some of the weaknesses of previous accounts.
