Abstract
The aim of design theory is to investigate the domain-independent natures of artifacts and design activities. The notion of function is important in design theory since design specifications are described in terms of functions, but it is not easy to define functions because the notion is closely related to our subjective intentions. In this report, we shall analyze the paradox of General Design Theory in in order to show the importance of the concept of function in a design theory, and we show that the concept has a correspondence with the notion of meanings of natural language expressions. Then, we give a formulation of the notion of function by using Situation Semantics which corresponds to Simion's definition of an artifact as an interface between its inner and outer environments. These arguments show the relationships between design theory and natural language semantics.
