The Functions of Definition in Science

Definition is viewed in this paper as a cohesive element of theory, providing links between scientific constructs. The problem is approached first in terms of three orders--the historical, the logical, and the heuristic--in which the structure of science may be put together; a study of these is necessary if difficulties about priority of definition are to be resolved. The main part of the paper is devoted to an exercise in theory-construction which illustrates the five principal functions of definition--the grounding of constructs in observation, their descriptive interrelation, the development of logico-mathematical calculi, the interpretation of these calculi, and the provision of precise, quasi-mathematical relations between the constructs themselves. Reference is made throughout to the many names for the defining process found in earlier works, and problems of contextual definition, reduction, stipulative and lexical definition, etc., are dealt with briefly. The theory thus constructed is represented diagrammatically. It is shown that the analysis may be simplified, in general terms, by the use of two new categories, "internal" and "external" definition; and that this innovation may prove helpful in clarifying some traditional obscurities, and in preserving a necessary balance between a purely logical and a purely empirical approach to the philosophy of science.