ABSTRACT
Epistemo-praxiology emphasises the various aspects of subjectivity. The use of observation operators helps to clarify the problem of indiscernibility. Observation cannot be separated from decision and from action: a system able to decide modifies its environment and also itself, it may act and be acted on. So, a synthesis of observation, decision and action, or of epistemology and praxiology, seems necessary. The knowledge to which a subject, interacting with an object, may have access, be it epistemological or pragmatic, is imperfect due to the limited capacities of the chains and to auto-referential difficulties. The epistemological and pragmatic images that system S has of its own evolution and that of its environment E, are determined by the evolution of the states of S and E, defined at a meta-level inaccessible to S, and by its observation and decision operators.
