lly for a particular research or theory building purpose.7
Three types of definition are relevant to scientific inquiry. First, an ostensive definition is "any process by which a person is taught to understand a word other than by the use of other words."8 Ostensive definitions are particularly useful in exploratory research, when concepts are being developed. Second, verbal definitions are used in scientific inquiry to explain concepts in terms of other concepts.9 Such definitions involve the use of words of approximately the same level of abstraction to assure that verbal definitions will aid in the understanding
5Abraham Kaplan, The Conduct of Inquiry: Methodologies for Behavioral Science (New York: Harper & Row, Publishers, 1964), 24 36.
8Bertrand Russell, Human Knowledge Its Scope and Limits (New York: Simon and Schuster, 1948), 63.
of the concept being explained. Third, operational definitions extend the level of abstraction, by defining a concept "in terms of specific testing criteria or operations."10 Such criteria must have empirical referents. Operational definitions must also state what phenomena will be observed and how such observation will be performed.
In scientific inquiry, a proposition is a statement "about concepts which may be judged as true or false if it refers to observable phenomena. When a proposition is formulated for empirical testing we call it a hypothesis."11 Hypotheses are declarative statements that are both tentative and conjectural in character. Hypotheses may be both descriptive and relational in form.
Theory, in scientific inquiry, is, in effect, a descriptive explanation of how something works an explanation of the interrelated actions within a system. While hypotheses may be derived from observed facts, they may also be deduced from theory.12 In scientific inquiry, theory provides a basis for the narrowing of the body of facts that must be studied to invest...