Scientific models have all these connotations. They are representations of states, objects, and events. They are idealized in the sense that they are less complicated than reality and hence easier to use for research purposes. These models are easier to manipulate and "carry" than the real thing. The simplicity of models, compared with reality, lies in the fact that only the relevant properties of reality are represented. For example, in a road map, which is a model of a portion of the earth's surface, vegetation is not shown, since it is not relevant with respect to the use of the map. In a model of a portion of the solar system the balls representing planets need not be made of the same material or have the same temperature as the planets themselves.
Scientific models are utilized to accumulate and relate the knowledge we have about different aspects of reality. They are used to reveal reality and - more than this - to serve as instruments for explainlng the past and the present, and for predicting and controlling the future. What control science gives us over reality we normally obtain by application of models. They are our descriptions and explanations of reality. A scientific model is, in effect, one or a set of statements about reality. These statements may be factual, law-like, or theoretical. (SM lO8-109)
and also. . . .
Theories and laws in pure science are frequently expressed in the form of mathematical models. Such theories and laws may play an important role in the decision models because the phenomena involved in the problem situation may behave in accordance with certain theories and laws. For example, a decision model which is constructed for use in selecting between alternative designs of equipment will generally contain physical laws which relate the performances of the various types of equipment to their characteristics.
The discussion of various types or models and approximations contained in this chapter is also applicable to the construction of quantitative theories and laws. Here too mathematical manageability and accuracy must be brought into balance. For example, the Ptolemaic (epicyclic) geocentric theory was replaced by the Copernican (circular) heliocentric theory largely because of the greater mathematical manageability of the latter. (SM l38)