Questions of Fact and Value: THE "IS" AND THE "OUGHT," MEANS AND ENDS
The distinction between fact and value calls first for a discussion of the grounds of knowledge-the basis for asserting a belief to be warranted or true. Given some understanding of the relevant issues, we can proceed to a discussion of means and ends, examining the meanings of these concepts and the relationships between them.
The questions that political scientists ask call sometimes for a study of what exists or happens, and sometimes for a study of what ought to exist or happen. Questions of the first sort are questions of fact, whereas those of the second sort are questions of value, though, as we will see, there is some ambiguity here. The same distinction can be made by saying that some questions call for descriptive statements and others for normative statements.
Descriptive statements, being factual, assert alleged truths about reality. They deal with what is, and not with what ought to be. Among other things, they identify relationships, e.g., the efficacy or the consequences of the employment of given methods or means. Or they may indicate what people do or believe or desire.
Normative statements express conceptions of the desirable. They indicate value preferences. They concern not what is but what ought to be, endorsing ends, purposes, or norms.