What do we mean by building function?

Scientific approaches to architecture usually avoid the issue of building form, preferring to focus on function. \nBut how can there be a theory of function without a systematic analysis of the key architectural variable of form? \nA theory of description is required. In this paper it is argued that such a theory can be built through the analysis \nof spatial form in buildings. Then once spatial form is describable in terms of a descriptive theory, a more powerfully scientific - and architectural - understanding of function is possible. The argument draws on several pieces of research carried out by the authors and their students, but focusses eventually on various types of medical building in order to illustrate certain general principles.