Psychosis and pathology: delirium in schizophrenia as harmful dysfunction

Delusions are regarded as one of the most complex symptoms of psychosis. With a higher prevalence in schizophrenia, the idea that delusions are ‘pathological’ is considered intuitive. However, the debate about what exactly makes delusions pathological is still open, especially when considering current proposals that claim that delusions would be beneficial in many ways for the subject. The harmful dysfunction criterion claims that a condition is pathological when (a) direct or indirect etiological mechanisms fail to perform the functions originally selected by evolution (dysfunctional element) and (b) this dysfunction negatively impacts the subject’s well-being (harmful condition). This paper examines the application of the harmful dysfunction criterion to the specific case of delusions in schizophrenia. First, we clarify some preliminary issues within the debate. Second, we assess the main objections and replies to the application of the criterion, and finally, we conclude by commenting on some of the main issues that seem to remain open within our target debate.