In Defence of Modest Doxasticism About Delusions

What are delusions? Examining the typology problem

Delusions are a heterogenous transdiagnostic phenomenon with a higher prevalence in schizophrenia. One of the most fundamental debates surrounding the philosophical understanding of delusions concerns the question about the type of mental state in which reports that we label as delusional are grounded, namely, the typology problem. The formulation of potential answers for this problem seems to have important repercussions for experimental research in clinical psychiatry and the development of psychotherapeutic tools for the treatment of delusions in clinical psychology. Problematically, such alternatives are scattered in the literature, making it difficult to follow the current development and state of the target discussion. This paper offers an updated critical examination of the alternatives to the typology problem currently available in the literature. After clarifying the two main philosophical views underlying the dominant formulation of the debate (interpretivism and functionalism), we follow the usual distinction between doxastic (the idea that delusions are a type of belief) and anti-doxastic views. We then introduce two new sub-distinctions; on the doxastic camp, we distinguish between revisionist and non-revisionist proposals; on the anti-doxastic camp, we distinguish between commonsensical and non-commonsensical anti-doxasticisms. After analyzing the main claims of each view, we conclude with some of the most fundamental challenges that remain open within the discussion. This article is categorized under: Philosophy > Foundations of Cognitive Science Philosophy > Consciousness Philosophy > Psychological Capacities Neuroscience > Cognition.

On the concept of delusions: Global trends and psychopathology in Japan

The present article spotlights challenging conceptual and epistemological issues regarding delusions. A research history of various approaches to delusions in Europe, the United States, and Japan reveals the difficulty of defining delusions. Facing these difficulties, the standard concept of delusions has become thinner than the traditional ones, making its boundary with minority opinions vaguer. Nevertheless, clinical typology and epistemological approaches are contributing to the continuous conceptual refinement of delusions. Both standpoints validate and promote each other in elaborating the characteristics of delusions and their boundaries with non-delusions. In addition, epistemological inquiries into delusions shed new light on the extraordinarily difficult problems in the relationship among belief, knowledge, certainty, and delusions, contributing to epistemology in general. These approaches to delusions promote the evolution of the concept of delusions and related epistemological inquiries.

Mapping the Psychotic Mind: a Review on the Subjective Structure of Thought Insertion

Delusions of thought insertion involve subjects claiming that external agents of different nature had placed thoughts into their minds/heads. However, despite being regarded as one of the most severe and complex symptoms of psychotic disorders, a number of disagreements surround the description of its most fundamental phenomenology. This work has reviewed classic and current research on thought insertion in order to examine and clarify its main experiential features as reported by patients from a first-person perspective. The review shows that such features can be grouped into two categories: (i) experiential changes characterizing the period preceding the adoption of the delusion and, (ii) subjective features of full-blown delusional cases. While the discussion of the latter set of experiential features has received some attention within literature, the examination of the former set has been largely neglected. After this, the review offers a discussion of the most important conceptual disagreements surrounding the phenomenological descriptions of the symptom. Overcoming disagreements regarding the experiential structure of thought insertion is fundamental to elaborate phenomenologically and empirically coherent explanatory theories of the symptom and advance its clinical treatment.

Uncovering Capgras delusion using a large-scale medical records database

BACKGROUND

Capgras delusion is scientifically important but most commonly reported as single case studies. Studies analysing large clinical records databases focus on common disorders but none have investigated rare syndromes.

AIMS

Identify cases of Capgras delusion and associated psychopathology, demographics, cognitive function and neuropathology in light of existing models.

METHOD

Combined computational data extraction and qualitative classification using 250 000 case records from South London and Maudsley Clinical Record Interactive Search (CRIS) database.

RESULTS

We identified 84 individuals and extracted diagnosis-matched comparison groups. Capgras was not 'monothematic' in the majority of cases. Most cases involved misidentified family members or close partners but others were misidentified in 25% of cases, contrary to dual-route face recognition models. Neuroimaging provided no evidence for predominantly right hemisphere damage. Individuals were ethnically diverse with a range of psychosis spectrum diagnoses.

CONCLUSIONS

Capgras is more diverse than current models assume. Identification of rare syndromes complements existing 'big data' approaches in psychiatry.

DECLARATION OF INTERESTS

V.B. is supported by a Wellcome Trust Seed Award in Science (200589/Z/16/Z) and the UCLH NIHR Biomedical Research Centre. S.W. is supported by a Wellcome Trust Strategic Award (WT098455MA). Q.D. has received a grant from King's Health Partners.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.