Some Problems of System Descriptions I: Function

Characteristics of functional descriptions (equivalent to descriptions of certain constraints) are examined. The question is raised whether these constraints are real. It is argued that they characterize a class of systems, called component-systems, which produce their own parts and constraints. Individual relations of components of these systems are argued not to be unifyable into one causal description. The concept of identity of systems is discussed, and it is suggested that systems having the above property lose their identity and should be redefined from time to time. Consequently, there is an inherent limitation in the conceptual tool of state-determined system that prevents its applicability in the present context. Functional descriptions are proposed to correspond to the irreducible boundary conditions that formally constrain the redefined systems.