Situated Software Design

In computer science we are used to characterize systems in terms of levels of virtual machines. In other words, we are dealing with virtual worlds. For virtual worlds the rationalistic perspective is well suited, i.e. general rules can be logically applied to situations characterized by objects with well-defined properties. However, software design is concerned with developing systems for the real world. The real world differs in several crucial points from virtual ones: it changes continuously, it is largely unpredictable, and it is only partially knowable. Many design approaches have not sufficiently taken these points into account. A number of alternative approaches have been proposed, but they have been largely ad-hoc and lack theoretical rigor. We show the need for a more suitable approach to software design. We believe that the idea of situatedness can provide the basis for such an approach. Situatedness is based on the fact that people are involved in a continuous interaction with a changing environment. People, e.g. software engineers and users of software systems are viewed as situated agents that bring to bear their prior experience on the particular situation. We discuss the importance of this view for software design methodology.