Dear Editor,

Walsh, in his recent article on the Great Irish Famine and Schizophrenia, suggests with respect to mania in the 19th century that other categories may be subsumed into it, most notably the 21st century concept of schizophrenia (Walsh, Reference Walsh2012).

Walsh's attempt to repopulate the 19th century with ICD-10 schizophrenia falls under a category of error that Historians of Psychiatry commonly call presentism: the tendency to interpret past events in terms of modern values and concepts. A psychiatric concept, however, cannot presuppose the conditions of its own possibility.

The concept of schizophrenia is historically complex. It has changed enormously over the last century – through definition, rates of diagnosis, nosology, symptom emphasis and so forth. And even today, for many, its validity remains contentious. Much the same may be said of mania in the 19th century. To attempt to subsume one into the other – even if detailed case studies did exist and the differential diagnosis of other organic conditions could be adequately considered – is therefore misguided.

The 19th century still has much to teach us about the origins of schizophrenia, about why it has been historically so unstable, and about why we describe and articulate the phenomenology of madness in the way we do. Understanding and using the methodology of historians is a vital tool in this learning process.