An Introduction to Systems Theory

In the traditional scientific method, sometimes referred to as divide and conquer, systems are broken into distinct parts so that the parts can be examined separately Physical aspects of systems are decomposed into separate physical components, while behavior is decomposed into discrete events over time. 

This decomposition (formally called analytic reduction) assumes that the separation is feasible that is, each component or subsystem operates independently, and analysis results are not distorted when these components are considered separately. This assumption in turn imphes that the components or events are not subject to feedback loops and other nonlinear interactions and that the behavior of the components is the same when examined singly as when they are playing their part in the whole. A third fundamental assumption is that the principles governing the assembling of the components into the whole are straightforward, that is, the interactions 

Three categories of systems (adapted from Gerald Weinberg, An Introduction to General Systems Thinking [John Wiley, 1975]). 

These are reasonable assumptions, it turns out, for many of the physical regularities of the universe. System theorists have described these systems as displaying organized simplicity (figure 3.1) [207]. Such systems can be separated into non-interacting subsystems for analysis purposes the precise nature of the component interactions is known and interactions can be examined pairwise. Analytic reduction has been highly effective in physics and is embodied in structural mechanics. 

---