One definition is the failure to function adequately this states that behaviour is abnormal if it prevents a person from leading a normal, everyday life and coping with everyday activities. This occurs when an individual is unable to engage in the normal ranges of behaviour and not been able to cope with the demands of everyday life for example work and doing the shopping. This behaviour is considered to be dysfunctional. Rosenhan and Seligman identified a number of characteristics that signal failure to function adequately and dysfunctional behaviour for example irrational behaviour displaying behaviour that cannot be explained in a ration reasonable way for example schizophrenia with paranoid delusions that’s makes them avoid family and friends because they believe that they are plotting against them.
A limitation of this is some people who are ‘abnormal’ can still function adequately in everyday life.
Psychopaths, people with personality disorders can commit murders and still appear normal for e.g. Harold Shipman was a doctor who murdered over 200 of his patients over 23 years however maintained a normal outward appearance.
These people are abnormal even though they don’t display many features of dysfunction in their everyday lives.
To add to this deciding whether someone has any of the features of abnormality is based on subjunctive (personal/individual) judgements.
For example a behaviour that causes observer discomfort to one person may not to another. It depends how the individual judges that behaviour. The same can be said for the other characteristics of failing to function adequately.
When judgements about dysfunction are made by others, they will inevitably be influenced by their personal and social beliefs and biases.
Another definition of abnormality is