Modern Western psychology and psychiatry arose in the context of the European Enlightenment of the 17th and 18th centuries. In the early 19th century, only two main mental illnesses were usually recognised – mania and melancholia (Shorter, 1997). As various theories of mental functioning came on the scene, new diagnoses were constructed in Europe and North America and two key diagnostic systems, the International Classification of Diseases (ICD) and Diagnostic and Statistical Manual of Mental Disorders (DSM), were developed. These are revised from time to time by groups of psychiatrists mainly living in the West and usually strongly influenced by pressure groups, including pharmaceutical companies wishing to market new remedies for illnesses. The first DSM (American Psychiatric Association, 1952) contained 60 diagnoses; the current edition, DSMIV (American Psychiatric Association, 1994), lists 297; and DSM-5, to be published in 2013, is likely to have even more (American Psychiatric Association, 2010).

A few diagnoses have fallen by the wayside. For example, gone are several popularised in the southern states of the USA as peculiar to Black slaves, such as drapetomania, characterised by persistent running away from the plantations (Cartwright, 1851). Homosexuality was listed as an illness in the DSM until the seventh printing of DSM-IV in 1974 and in the ICD until ICD-10, published in 1990 (Shorter, 1997). Well into the 1960s, depression was reported as rare among Asian and African people and Black Americans, a rarity attributed to their supposed irresponsible nature (Green, 1914) and absence of a sense of responsibility (Carothers, 1953).

A multi-ethnic society includes people whose backgrounds are culturally diverse as well as people seen as different in terms of race. No psychiatric diagnosis has an established biological marker; hence, there is no way of proving objectively its accuracy or its validity as a measure of a biological reality applicable to all human beings. Kendell & Jablensky (2003) describe diagnostic categories as ‘simply concepts, justified only by whether they provide a useful framework for organizing and explaining the complexity of clinical experience in order to derive inferences about outcome and to guide decisions about treatment’. They warn against reifying a diagnosis by assuming that it is ‘an entity of some kind that can be evoked to explain the patient's symptoms and whose validity need not be questioned’.