Hypotbeses, Rules, and Principles
The discussion of the level of generality of questions which appeared in Chapter Two necessarily included some statements about classification and generalization, and the words have been mentioned at other points as well. But a more extended and coherent discussion of them will be helpful. Moreover, in this chapter the notion of classifying will be supplemented with the notion of ordering; and three kinds of generalizations--hypotheses, rules, and principles-will be discussed.
Classification consists of grouping items or phenomena on the basis of their shared characteristics. Whether or not a class of items is named (i.e., whether or not they provide a basis for the formulation of a concept), the process of classification is tremendously important. "This ability to order things into likes and unlikes is, I think, the foundation of human thought."1
The basic purpose of classification is to simplify the handling of a great number of individual items by putting them into a smaller number of groups, each group consisting of items which act more or less alike in relation to the problem being studied.2
Classification may involve a series of steps. For some purposes it is enough to divide items into very broad and general categories, as when we classify political actors as governmental and nongovernmental. For other purposes sharper differentiations are desir