Introduction

One of our goals as we seek to increase our understanding in an area of human knowledge is to develop models and theories. Definitions of what constitutes a model and a theory are many, and the terms may be used with varying degrees of stringency. But basically they are representations of our thinking about a phenomenon at a particular time and from a particular point of view. Different researchers and writers may define models and theories in different ways. However, the terms as used in this book are defined below.

Understanding of a phenomenon is often represented as a ‘model’ of that phenomenon. By ‘model’, I simply mean a representation (often, but not always, in diagrammatic form) of our understanding about something.

An ‘explanatory’ (or ‘propositional’) model seeks to explain some phenomenon by making explicit the key concepts that constitute it, and the relationships between these concepts. A ‘descriptive’ (rather than explanatory) model may simply map out the component parts of a phenomenon like a sort of ‘road map’, without going on to specify in much detail the nature of relationships between these concepts. Often there will be links between the concepts (often represented as lines or arrows between boxes in diagrammatic form) but the nature of the links is not elaborated in a lot of detail. These different terms (‘explanatory’ and ‘descriptive’) are used simply to differentiate models of different complexity, and the dividing line between the two is subject to interpretation.

Take, for example, Wilson's well known model of information behaviour (Wilson and Walsh, 1996), shown in Figure 7.2 on p. 144. The diagram appears as a descriptive model in which concepts appear in boxes linked by unlabelled arrows which do not make clear the precise relationships between the boxes. However, when the model is viewed in conjunction with reading the text provided by Wilson in the article presenting the model, where he elaborates and explains the various elements and their inter relationships, the model becomes less descriptive and more explanatory. Note that differences between ‘descriptive’ and ‘explanatory’ relate to the intent of a model rather than the strength of evidence to support it. Thus, the explanation represented in an explanatory model may be either hypothetical or based on substantial evidence.