On Engineering Meanings and Representations of Technical Functions

In this paper I consider the relations between the different meanings and representations of the concept of technical function that are in use in engineering design methodology. I focus on two representation schemes — the verb-noun and the operation-on-flows representations — and analyse whether representations of technical functions created with the one scheme can be transposed into representations of the same functions with the other scheme. I argue that the answer depends on the particular meaning of function that one adopts. When functions of technical systems refer to behaviours of those systems, then the two representations can be reciprocally transposed following the rule that the verbs in the verb-noun representations correspond to the operations in the operation-on-flows representations, and the nouns to the (main) flows. When, however, technical functions refer to the purposes for which systems are designed, it can be argued that these representations cannot be transposed using this rule. The reason for this result is that operation-on-flows combinations, where the flows are flows through technical systems, are, in general, not suited to represent purposive technical functions of the systems. In a subsidiary and more explorative discussion I focus on the transposition of verb-noun representations of purposive functions into operation-on-flows representations of behavioural functions in design methodologies such as the Functional Basis account of Robert Stone and Kristin Wood.