Discuss 'deviation from social norms' as a definition of abnormality

Deviation from social norms refers to deviation from unstated rules about how one ought to behave: anything that violates these rules must then be consider abnormal. In society there are standards of acceptable behaviour set by social groups, adhered to by those socialised into the group. Some rules are implicit, whereas others are policed by laws. For example, in the past homosexuality was classified as abnormal and even regarded as a mental disorder, but it is now socially accepted. other forms of sexual behaviours, however, are still considered abnormal - such as paedophilia - because they deviated from social norms of what is acceptable.
the deviation from social norms definition of abnormality has many strengths. For example, the theory makes it easy to distinguish clear abnormalities as we can distinguish between desirable and undesirable behaviours, and once they are identified they can then be treated if necessary. Furthermore, the definition has real world applications that make it useful for society: adhering to social norms means that society is ordered and predictable, making society safer, more peaceful and more harmonious. On the other hand, the definition only has temporal validity. Behaviour such as homosexual marriage was against society’s norms 50-60 years ago, yet now it is socially accepted - this means that the model is unable to accurately define abnormality due to the constant shifts in societal views. Finally, the definition suffers from a cultural bias as it is culturally relative: behaviours may be expected in one but wholly unacceptable in another. Social norms are not universal, therefore not behaving in a certain way doesn’t simply define a person as abnormal.