Two kinds of theory?

To make sense of these ruminations on layered decomposition of instructional design problems one has to accept a distinction between two kinds of theory: instructional design theory and instructional theory. To put this in general terms, it means for designers accepting the existence of two kinds of design-related theory--one kind pertaining to how things are designed, and one pertaining to what kinds of structures those designs might contain. The first of these can be called a design theory; the second can be called a domain theory. 

Donald Schon (umlat over the "o") describes domain theories in some detail in "Educating the Reflective Practitioner" (Jossey-Bass, 1989). He gives an account of a tutor helping a student solve an architectural problem. In the process, Schon reveals his view that different parts of the problem become most critical at particular times and that each sub-problem constitutes a "domain" which has its own terminology, principles, and practitioners.

At the same time as we acknowledge domain theory as a kind of theory required by designers, we can also see that designers draw on another type of theory--design theory--which is theory about how something is or can be designed.The subject of Herbert Simon's "Sciences of the Artificial" was this kind of theory.

The two types of theory relevant to a designer may puzzle the scientifically-oriented person, who is used to there being only one kind of theory--and that an explanatory , not a synthetic, kind. What answers this puzzlement is the realization that designers use theory, but that the theory is not scientific theory: it is design-related theory. Moreover, the identification of two kinds of design related-theory (with the expectation of even more being identified) means that design-related theory is a different species of theory with different properties and different uses: technological theory.