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The Problem of Defining Delusion

This post is by Giulia Cavaliere and James Rubert Fletcher, both PhD students in Social Science, Health and Medicine, King's College London.  



On November 12th, the third event organized by King’s College London’s new joint venture Philosophy & Medicine took place. Previous events have featured colloquiums about placebo-controlled clinical trials and the challenges of communicating cancer risk. This third colloquium focused instead on the issue of mental health and in particular on the problem of defining delusion.

The first part of the colloquium was led by Dr Abdi Sanati, a consultant psychiatrist and a philosophy scholar from the North East London NHS Foundation Trust. Dr Sanati opened with the description of a clinical case concerning a woman experiencing problems with a prosthesis and reporting her wish to have it removed. Her doctors originally encouraged her to keep the prosthesis, addressing her discomfort as something “delusional”. Eventually, after many painful examinations, it was discovered that there was indeed something wrong with her prosthesis.

Dr Sanati used this case to illustrate both the theoretical difficulties of clearly identifying something as a delusion and the practical implications in real-life cases of labelling something as a delusion. After this introduction, Dr Sanati briefly presented the work of Karl Jaspers on delusion and the definitions used respectively in the 4th and 5th editions of the DSM (Diagnostic and Statistical Manual of Mental Disorders), in which delusions were firstly defined as “false beliefs” and then as “fixed beliefs”. 

After outlining various critiques of these definitions, proposed especially by philosophy scholars, Dr Sanati shifted to the contribution of contemporary influential authors as Berrios, Campbell and Bortolotti in framing the concept of delusion. His talk aimed at showing both the theoretical difficulties and controversies concerning the definition of delusion and the importance of the contribution from philosophy in this search for a definition – a search that has not yet come to an end.

On this issue, fellow guest, Dr Luis Flores, commented that philosophy can help to test the consistency of the definitions and ideas put forward by psychiatrists, but it can also question the validity of such a heterogeneous concept altogether.

The talk was followed by a very active discussion between Dr Flores, Dr Sanati and the audience. Students and researchers from philosophy, medicine and social science dialogically expressed their views, doubts and concerns.

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