Vermaas and Dorst’s mind the design process covers a more extended range
than a translation of some requirements into a functional specification. Indeed,
the term ‘Purpose’ and its relationships with Function had been already
investigated by Gero himself in Rosenman and Gero (1998), where the design
process is depicted as starting from a ‘Purpose’ (or ‘intent’). The design process starts with the interpretation of Function as a means to achieve a given Purpose.
While the paper discusses how Purpose expresses human values of utility and its impact on the interpretation of FBS variables, the same limitations observed above about a lack of distinction between Needs and Requirements apply.
Moreover, the concept of Purpose has not been ‘situated’ in the following works by Gero and collaborators; as a consequence, the current situated FBS model misses to represent the cognitive processes that occur or might occur while identifying Needs, or while building a Requirements specification.