Information, Computation, Cognition. Agency-based Hierarchies of Levels

Nature can be seen as informational structure with computational dynamics (info-computationalism), where an (info-computational) agent is needed for the potential information of the world to actualize. Starting from the definition of information as the difference in one physical system that makes a difference in another physical system, which combines Bateson and Hewitt definitions, the argument is advanced for natural computation as a computational model of the dynamics of the physical world where information processing is constantly going on, on a variety of levels of organization. This setting helps elucidating the relationships between computation, information, agency and cognition, within the common conceptual framework, which has special relevance for biology and robotics.