Almost as important as the notion of system is the notion of
of a system. Investigating systems mostly comes down to building models and analyzing the behavior of these models. Mathematics and logic provide the means to build complex but exact conceptual models and to analyze the behavior of these models thoroughly. The only weak point is the validation of the model against the modeled system. Is the model appropriate? Is it sufficiently accurate? What are the ranges of reliability? Can one predict the behavior of the system on the basis of the behavior of its model?