Beyond Oz's Curtain: A Recharacterisation of Monothematic Delusions through Consequential Harm

Monothematic delusions (MDs) are a specific type of delusion characterised as having a single theme (Coltheart,2013). For instance, Cotard delusion is the belief that one is dead or does not exist (Coltheart, 2005). There is currently vast disagreement amongst philosophers regarding how MDs should be defined, ranging from whether they are a form of belief, to whether their content contradicts external reality, to whether they are irrational (Frith,2015; McKay et al., 2010; Sullivan-Bissett, 2020; Noordhof and Sullivan-Bissett, 2021).

This lack of consensus makes justifying the pathologisation of MDs and implementing appropriate medical interventions problematic, alongside having theoretical uncertainty.

This PhD research will propose a novel account of MDs grounded in their consequential harm, rather than belief content. To wit, the category of beliefs called 'delusions' is populated with beliefs with harmful consequences rather than having another unique feature, such as being irrational as suggested in some current accounts. From this, it follows that MDs can be justifiably pathologised due to their consequential harm, avoiding the problems facing other accounts.

This shift aligns with contemporary mental health paradigms. For instance, Agoraphobia is not pathologised by the fear of leaving the house, but instead by an appeal to the consequence of the individual being unable to leave the home. For MDs, it is not the content of the belief that warrants pathologisation, but instead the harmful consequences of holding the belief like impeding upon typical daily functioning.

Thus, this research will have clinical relevance like potentially improving diagnostic precision and treatment strategies. It will also combat major ethical concerns shrouding current approaches since the emphasis on measurable harm safeguards against historical abuses of power by authorities in pathologising certain behaviours or beliefs, like homosexuality (Lacombe, 1996).

The research will comprise four main components: Analysis of the current debate in terms of common underlying criteria and assumptions.

Three core criteria will be identified: 1) assumption that there is a universal standard of rationality, 2) assumption that there is a universal and objective external reality, and 3) cultural beliefs should be excluded from delusion categorisations. Rejection of current approaches.

The aforementioned core criteria will be shown as unsuitable measures for defining MDs for an array of reasons, including the difficulty in identifying what constitutes a cultural belief, the prevalence of 'irrational' beliefs across the population (like self-deception), and the difficulties in verifying another individual's sensory experiences.

Proposal of novel account that grounds MDs in consequential harm

The new account will be demonstrated to align with current approaches to mental disorders, such as anxiety disorders, justifying the pathologisation of MDs through their resultant harm rather than because of the content of the belief. Defence of novel account

This account will be demonstrated to yield a better conception of MDs compared to current approaches. The shift to align with current approaches to mental disorders will safeguard individuals from being pathologised solely by their belief system and favour a framework that is already proven to provide appropriate medical intervention for individuals.