In everyday language, 'to deviate' means 'to stray from an accepted path'. Most sociological definitions simply elaborate on this idea. Thus deviance consists of those acts, which do not follow the norms and expectations of a particular group. Deviance may be positively sanctioned (rewarded), negatively sanctioned (punished), or simply accepted or tolerated.
A soldier on a battlefield, who risks his life beyond the call of duty, may be termed deviant, as may a scientist who breaks the rules of the discipline and develops a new theory. Their deviance may be positively sanctioned; the soldier might get a medal; the physicist the Nobel prize. In another sense, neither is deviant, since both conform to the values of their society, the soldier to the value of courage, the scientist to the value of academic progress.
By comparison, a murderer not only deviates from society's norms and expectations, but also from its values - in this case the value placed on human life. This deviance results in widespread disapproval and (if the murderer is caught) punishment. The third form of deviance consists of acts, which depart from the norms of a particular society, but are generally tolerated, for example, eccentrics and beggars. Also in this group of deviants come those who depart from norms because they don't know they exist, or have forgotten them, for example children, or people with learning disabilities. Generally, this form of deviance is tolerated and seen as relatively harmless.
In practice, the study of deviance is usually limited to deviance that results in negative sanctions. In fact, the American sociologist, M. Clinard, has suggested that the term deviance should only be applied to behaviour that is disapproved of, and punished by a community.
It is vitally important to recognise that deviance is relative, the context in which behaviour occurs is crucial to how it will be evaluated. This means that there is not an absolute way of defining a deviant act. Deviance can only be defined in relation to a particular standard of behaviour, and no standards are fixed forever as absolutes. As such, deviance varies from time-to-time, place-to-place and person-to-person.
In one society, an act that is considered deviant today, may be defined as normal in the future. Possible examples are polygamy, one-parent families, or the age of consent. An act defined as deviant in one society may be seen as perfectly normal in another. Deviance is culturally determined, and cultures differ both from each other, and within the same culture over time. In the same way, definitions of crime change over time. Homosexuality was formerly a criminal offence in Britain, but since 1965, this is no longer the case. Homosexual practices have not changed but public reaction to them has.
Deviance then refers to those activities that do not conform to the norms and expectations of a particular group or society.
Non-sociological understanding of deviance tends to acknowledge the presence of something within the individual that compels, or at least orientates, them to commit certain acts. For example, up until the 1700s, the basic approach to deviance was to view it as a result of biological actions that affected particular individuals. Thus people became deviant if they had an imbalance in bodily humours (blood, mucus, yellow bile, black bile).
Other theories, such as that of Lavater involved measuring heads. In the early 20th century, Lombroso argued that criminals had particular physical features.
The combination of biological features with psychological predispositions came in the mid 20th century; Kretschmer (1951), and Sheldon (1949). In more recent times, there has been an association between chromosomes and deviant behaviour (Price), Eysenck (1970) and the development of the idea of a genetic constitution, and Raboch and Sipova (1974) arguing the importance of hormones.
The very idea of the born criminal/deviant is a very strong part of our popular culture, and it has the enormous side benefit of directing blame at the deviant individual, while excluding social factors.
It was not really until the 1950s that sociological explanations started to compete with biological or psychological explanations. Even then, these sociological approaches were similar to the existing theories, in that they were positivist - based on the modernist idea that it is possible and desirable to attain rational, and verifiable knowledge. The difference was, that for sociologists, the causes of deviant behaviour are found outside the individual. Such explanations then, as with much sociology, are a rejection of individualistic explanations of behaviour. This is the approach of social positivists.
As already noted, the challenge to non-sociological approaches to deviance began in about the middle of the 20th century. These were theories of the delinquent subculture. However, these theories were developments of earlier work, notably the work of Durkheim and Merton.