Soft Systems Methodology

Soft Systems Methodology (SSM) was devised by Checkland (1981) and elaborated by Checkland & Scholes (1990) to provide a tool for investigating an unstructured problem situation. SSM is not a system design tool, but a tool for system requirements investigation. Unlike systems analysis tools, such as entity-relationship modelling or data-flow diagrams, which allow the designer to model how the system should operate, SSM questions what operations the system should perform and, more importantly, why. Thus SSM provides a "soft" investigation (into what the system should do) which can be used to precede the "hard" investigation (into how the system should do it). Figure 1 illustrates the purpose of SSM; it should be noted that SSM does not produce either a set of information system requirements or an information system design. SSM produces a set of feasible and culturally-acceptable actions which can be taken to improve the problem situation. These actions may be used to produce a set of information systems requirements, but it is more helpful to see them as a set of organisational process improvements, where a process is a set of organisational tasks performed purposefully by a human actor or actors.