Conclusions This review began with ‘unitary psychosis’. Has this ceased to exist because there is no code for it in ICD-10 or DSM-IV? Should those who regard basic schizophrenic phenomena as symptoms of dysfunctions in the central nervous system classify them under F06.2 (organic schizophrenia-like disorder) or F20 (schizophrenia)? Another problem of the same order concerns the significance of the difference between G93.3 (postviral fatigue syndrome) and F48, which includes fatigue syndrome. Being able to pose these questions does not demonstrate the futility of providing standardized definitions for international use. The examples do not inspire confidence but the effort to provide reference criteria is essential. It does demonstrate that, whether called ‘diseases’  or ‘disorders’,  we are dealing with constantly changing concepts. That is not all. The same is true of ‘syndromes’ and of ‘symptoms’. They, too, are concepts that must compete with each other. The more precisely they, and the predictions that follow from them,  are stated,  the more easily they can be refuted if they are wrong. It may pay, in the short term, to be vague; however, a greater distraction from the search for knowledge is that some protagonists,  even when using an impeccably sceptical approach in their scientific work, tend to use the terminology of ‘disease entities’ and seem to want to believe that the Snark or the Boojum really exist. Others react against each such provocation and waste their time and wit in polemic. Such arguments are inevitable and will continue. However, looking back from this new vantage point, it is still possible to discern a pattern amid the noise. J.K. Wing and N. Agrawal

Edited by
Steven R. Hirsch
MD FRCP FRCPsych
Professor of Psychiatry Emeritus, Division of Neuroscience and Psychological Medicine Imperial College Faculty of Medicine and Director of Teaching Governance, West London Mental Health NHS Trust London, UK

Daniel R. Weinberger MD
Chief, Clinical Brain Disorders Branch Intramural Research Program National Institute of Mental Health Bethesda MD 20982, USA

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