Soft Systems Methodology
The Real World Vs. Systems Thinking About The Real World
The purpose of SSM is to produce structured models that help in our thinking about the real world. But it is important to understand that these do not represent the real world. SSM is a process of analyzing subsets of human activity, to understand this activity at a deep level and to suggest ways of acting that improve the current "problem-situation". It is not a way of modeling systems of work as they exist, or of defining computer-system functions.

Systems thinking attempts to understand problems systemically. Problems are ultimately subjective: we select things to include and things to exclude from our problem analysis (the "system boundary"). Real-world problems are also interrelated" by solving one problem, we often make another problem worse, or complicate matters in some way. So systemic thinking attempts to understand the interrelatedness of problems and goals by separating them out. In understanding different sets of activities and the problems pertaining to those activities as conceptually-separated models, we understand also the complexity of the whole "system" of work and the interrelatedness of things - at least, to some extent.

However sophisticated the models become and whatever models we use (SSM, UML, DFDs, Entity-Relationship diagrams, etc.) we should always remember that a model is a reduced "window" onto the real world. Whatever insights a model may give us, it does not represent the real world.