Alcoholism is a complex, many-sided phenomenon, and its many formal definitions vary according to the point of view of the definer. A simplistic definition calls alcoholism a disease caused by chronic, compulsive drinking. A purely pharmacological-physiological definition of alcoholism classifies it as a drug addiction that requires imbibing increasing doses to produce desired effects and that causes a withdrawal syndrome when drinking is stopped. This definition is inadequate, however, because alcoholics, unlike other drug addicts, do not always need ever-increasing doses of alcohol.