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Free download from www.hsrcpress.ac.zamaintain that the differences between models and theories are largelydifferences of degree. Although it is not always essential that a rigid distinctionbe drawn between model and theory, the differences between these twoconstructs will be emphasized here.In the process we shall argue that the heuristic function is the most commoncharacteristic of models, while the explanatory function is usually attributed totheories.The fundamental relationship between model and analogy is discussed byGiere:The use of models in science can be described in general terms as follows.There is a type of system, such as atoms, about which not much is known.However, there are other systems such as solar systems, about which a lot isknown. In 1900 there were already good theories of solar systems (e.g.Newton’s). Someone then suggests that maybe the unknown type of system islike the known one in certain important respects. This in turn suggestsquestions that one should ask about the unknown system: How fast are theelectrons moving around their orbits? Are the orbits circular or elliptical? andso on. The model also suggests ways of answering the questions ...So it is clearthat models as the basis of analogies do play an important role in scientificresearch — that is, in the creation of new theories (1979: 79).In this case an established theory of the planetary system was used as thesource for the construction of a model of the relatively unknown phenomenonof atoms. We encounter the same situation in the social sciences where modelsof political dynamics (Easton’s systems theory model), or models of problemsolving (Popper’s evolutionary theory) have their origin in the biologicalsciences. This analogical relationship does not, however, only exist betweenthe better-known and the less well-known (the new) model, but also betweenthe model and the real-life phenomena of which it is the model. As Kaplan(1964: 265) indicated, this has led to models also being known as scientificmetaphors. By investigating a specific phenomenon, the researcher revealscertain similarities or relationships, and systematizes these (in a simplifiedform) as a model of that phenomenon. One could claim that the model is an ‘asif framework’ in which a model of X would claim that X is structured in themanner suggested by the model. We can illustrate this as if character ofmodels very clearly by means of one of the well-known models in the field ofcommunication science, i.e. Shannon and Weaver’s (1948) model of thecommunication process.In this model certain aspects of the communication process are highlighted,namely information and the accuracy of information transfer. One of theimpediments to reliable communication is noise, that is, undesirable signalsthat have a negative influence on reliability.139