Department of History and Philosophy of Science will hold the 61st Tokyo Colloquium of Cognitive Philosophy. Everyone is welcome.

Date & Time: Jul. 29th (Fri.), 2016, 17:00-19:00
Venue: KIBER (国際教育研究棟), Room 110 on the 1st floor, Komaba Campus, The University of Tokyo.
(http://www.u-tokyo.ac.jp/campusmap/cam02_01_05_j.html)

Presenter: Eisuke Sakakibara (The University of Tokyo)
Title: Bizarre delusions as an understandable response to abnormal experience: Maher’s theory of delusion revisited

Abstract:
Jaspers (1913) claimed that bizarre delusions typically held by patients with schizophrenia are incomprehensible. In contrast, Maher (1974), proposed that schizophrenic delusions are hypotheses formed to explain a patient’s abnormal experiences, and that they are “rational, given the intensity of the experiences that they are developed to explain.” The “two-factor” theory of delusions attacked Maher’s theory because (1) it does not explain why some patients with abnormal experiences do not develop delusions, and (2) considering the totality of experiences and other beliefs held by patients, adopting and adhering delusional hypotheses is far from rational. In this presentation, I will defend Maher’s position by reformulating it to maintain that bizarre delusions are understandable, rather than rational, given the patient’s abnormal experiences. Regarding (1), two-factor theorists’ requirement is excessive, because it is generally impossible to identify universally sufficient conditions for a given transition of mental states or actions to occur. Regarding (2), we must acknowledge that holding delusions is understandable but irrational in three ways, namely epistemic, procedural, and agential. Epistemic irrationality of delusions is understandable given the preoccupation with imminent situations generated by the intensity of abnormal experience. Procedural and agential irrationalities of delusions, also known as the “circumscription” of delusions, are understandable given that patients are aware of the inconsistencies between their delusions and the other beliefs they hold. Circumscription is motivated by the desire to “minimize doxastic disruption.” It is not entirely safe, in terms of academic rigor, to directly compare schizophrenic patients with cognitively normal people confronted by abnormal experiences. However, there are two practical merits in incorporating what Jaspers considered to be incomprehensible into the realm of the understandable by presupposing abnormal experiences. First, it works as a heuristic for elucidating neural underpinnings of delusions. Second, the possibility of psychotherapeutic intervention for patients with delusion is increased.