Definitions of Mental Health

Definitions of Abnormality

Defining what is meant by "abnormality" in psychology is considerably more difficult than it might first appear. Any definition must distinguish between behaviour, thoughts, or emotions that are merely unusual and those that are genuinely disordered in a clinically meaningful sense. Psychologists have proposed four main definitions, each capturing a different dimension of abnormality — and each facing its own set of limitations.

Statistical Infrequency

The statistical infrequency definition proposes that behaviour is abnormal if it is statistically rare — that is, if it deviates significantly from the average for the population. This approach draws on the normal distribution: most psychological traits (such as intelligence, anxiety levels, and extraversion) are distributed in a bell curve, with the majority of people clustering near the mean. Behaviour or characteristics that fall in the extreme tails — typically defined as more than two standard deviations from the mean — are classified as abnormal.

A clear limitation is that statistical rarity is not sufficient to define disorder. An IQ above 130 is statistically infrequent but is not considered a disorder. Conversely, mild depression, which is very common, would not qualify as abnormal under this definition even though it causes significant distress. The definition also provides no guidance on which end of the distribution to be concerned about, and takes no account of the cultural context of behaviour.

Failure to Function Adequately

The failure to function adequately (FFA) definition proposes that behaviour is abnormal when it prevents a person from leading a normal daily life — when they are unable to maintain self-care, hold down employment, sustain relationships, or engage in the activities expected of a person in their social role. Rosenhan and Seligman (1989) suggested several criteria including personal distress, maladaptiveness, unpredictability, irrationality, and observer discomfort.

This approach is more practically useful — clinicians are often precisely concerned with how much a disorder is interfering with daily functioning. However, it is difficult to define what "adequate" functioning means across different contexts and cultures. Some individuals with severe mental health difficulties (e.g. certain forms of OCD) may function at a very high level professionally whilst experiencing significant private distress. Additionally, some failure to function may be a rational response to difficult circumstances rather than evidence of disorder.

Deviation from Ideal Mental Health

Marie Jahoda (1958) took a positive approach, defining abnormality as the absence of positive psychological wellbeing — or ideal mental health. She proposed six criteria for ideal mental health: positive self-attitude; personal growth and self-actualisation; autonomy and independence; accurate perception of reality; environmental mastery (the ability to meet the demands of daily life); and resistance to stress.

Whilst this definition is humanistic and avoids the medicalisation of distress, it sets an extraordinarily high standard — virtually no one would meet all six criteria consistently. The criteria are also strongly influenced by Western, individualist cultural values: autonomy and independence are not universally valued, and what constitutes "accurate perception of reality" or "environmental mastery" varies across cultures.

Deviation from Social Norms

The deviation from social norms definition proposes that behaviour is abnormal when it violates the implicit rules and standards that govern conduct within a society. Every culture has norms about acceptable behaviour — wearing appropriate clothing, maintaining personal hygiene, not talking to imaginary people in public — and behaviour that transgresses these norms is classified as abnormal.

This definition captures the social context of disorder but is highly culture- and time-dependent. Homosexuality was classified as a mental disorder in the DSM until 1973 — a reminder that social norms can be used to pathologise behaviour that is merely non-conformist or politically inconvenient. The definition also provides no clear threshold between eccentricity and disorder, and is vulnerable to abuse by those in power who wish to define dissent as illness.