What is normal?

The distinction between normality and abnormality forms the basis of medical practice. However, these words appear to have no more precise meanings in medicine than they do in conversational English. At least five contradictory definitions are described in the literature, and are in simultaneous use in everyday practice. The apparently arbitrary manner in which these definitions are chosen to evaluate different phenomena effectively means that medicine operates without a definition: certain phenomena are normal (by decree, as it were), and others are not. Actions based on such an arbitrary system are, of necessity, haphazard. The adoption of a precise, rigorously acultural definition of normality would unquestionably admit medicine to full membership of the family of objective sciences.