The Meaning of Normal

THE MEANING OF NORMAL PHILLIP V. DAVIS* and JOHN G. BRADLEY Everyone knows what "normal" is. Imbedded in nearly everyjudgment that we make, every comparison, and every weighing of possibilities is a firmly developed concept of what's "normal." And, while the definition varies with the referent, it generally describes some commonly held understanding , a culturally accepted belief about what is typical, usual, and natural . The "normal price of goods," for example, describes the typical cost of items when discounts and sales are ignored. "Normal body temperature " refers to the usual temperature measured in a healthy person. "Normal behavior' ' describes natural, expected actions. We depend, in fact, on having a common understanding of "normal" in order to make a number of judgments. In medicine, particularly, beliefs about what is normal are central in making judgments about disease. In a classic article entitled "The Normal, and the Perils of the Sylleptic Argument," Edmond Murphy posits a number ofdifferent uses of the word normalthat illustratejust how complicated this common understanding can be [I]. Normal, Murphy suggests, means ' 'typical'' when appealing to a commonly accepted practice. It means "average" when describing what is most representative of a class or group. When used to give assurance in a clinical setting, normal means "innocuous" or "harmless." In genetics, it defines what is "most suited" for survival. When used in statistics, Murphy suggests that the meaning is technically specific. Finally, Murphy notes that when we makejudgments about absolute goals, when we talk about what is desirable , we sometimes use the word normal as a synonym for "perfection." Murphy's observations suggest two potential dangers in the belief that we genuinely understand what normal means. The first is the hazard of assuming that we understand the intended use of the word normalin any given context (as in what the word normal means in the phrase "normal sexual relations"). The second is that the contextual meaning of the word may be revised and thereby change our understanding of the phenomenon it *Department of Medical Humanities, Southern Illinois University, P.O. Box 19230, Springfield , IL 62794.© 1996 by The University of Chicago. All rights reserved. 0031-5982/96/3904-0964$01.00 68 Phillip V. Davis andJohn G. Bradley ¦ Meaning ofNormal describes. "Normal highway speed," for instance, is often more dependent on the speed of surrounding traffic than on the posted speed limits. In the same way, the concept of "normal social behavior" changes. For example, Daniel Moynihan suggests in an article entitled "Defining Deviancy Down" that societies can criminalize actions only to the extent that their justice systems can handle the results [2] . When more deviant behavior exists than the structure can deal with— e.g., than prisons can hold— the range of acceptable behaviors is broadened. What had been "criminal" becomes "normal." In medicine, there is particular danger in shifting the contextual meanings of the word normal, in part because of the large range of meanings that the discipline allows the word, and in part because the result of allowing one definition to take the place of another changes the way in which physicians define disease itself. Medicine uses the word normal to express all of the various meanings that Murphy describes, and it appears to extend the use of the word to include a number of other meanings. In medicine, normal can refer to a "defined standard," such as normal blood pressure; a "naturally occurring state," such as normal immunity; or simply mean "free from disease," as in a normal pap smear. It can mean "balanced " as in a normal diet, "acceptable" as in normal behavior, or it can be used to describe a "stable physical state." In all of these meanings, the word normal is used to describe an "ordinary finding" or an "expected state." But medicine allows another meaning for the word normal that differs significantly from the ordinary. In many ways, medicine has come to understand normal as a "description of the ideal." Medicine's identification of the normal with the ideal may stem from a related concept: the definition of the clinical term norm. Dorland's Medical Dictionary defines norm as a "fixed or ideal standard" —that is, an ideal standard against...