Monothematic Delusions and the Limits of Rationality

Adam BRADLEY, Quinn Hiroshi GIBSON

Research output: Journal PublicationsJournal Article (refereed)peer-review

1 Citation (Scopus)


Monothematic delusions are delusions whose contents pertain to a single subject matter. Examples include Capgras delusion, the delusion that a loved one has been replaced by an impostor, and Cotard delusion, the delusion that one is dead or does not exist. Two-factor accounts of such delusions hold that they are the result of both an experiential deficit, for instance flattened affect, coupled with an aberrative cognitive response to that deficit. In this article, we develop a new expressivist two-factor account of delusion. In contrast to existing endorsement and explanationist accounts, which treat delusions as either explanations or endorsements of the contents of these disordered experiences, we hold that delusional beliefs have an expressive function: they characterize, in impressionistic terms, what the subject’s experience is like for them. We show how our account improves upon existing two-factor views in explaining the central features of monothematic delusions, in particular the way in which delusional subjects fall short of the ideal of rationality.
Original languageEnglish
Pages (from-to)811-835
Number of pages25
JournalBritish Journal for the Philosophy of Science
Issue number3
Early online date11 Aug 2023
Publication statusPublished - Sept 2023

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© The British Society for the Philosophy of Science.


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