title: [Capgras syndrome and possible worlds or places where the real person and its imposter coexist].
abstract: In a previous paper, the author has argued that what actually changes in the person whom the Capgras patient has chosen as his/her target of delusion is non-attribute <I> such as having only "haecceity." At the same time, the author has pointed out that such ever-identical <I> is also the target of the indication for the rigid designator as proposed by S. Kripke. Such problems with indication and identity, however, are closely associated with ontology presented by possible worlds semantics, an analytic philosophy that was much debated during the latter half of the 20th century. The purpose of this paper is to try to define the essence of Capgras syndrome from the viewpoint of possible worlds semantics. If Capgras syndrome is taken as suggested by the patient's statement that "a real person has been replaced by an imposter," it is though that this statement refers to metaphysics with regard to the number of individuals who exist in the world. This is because the appearance of the imposter means the generation of a new individual who had not been in existence until that time. The creation of the new individual not only demands the existence of plural worlds as addressed by possible worlds semantics, but also provides a clue to solving problems with places where the real person and its imposter exist. If the number of individuals existing in the world is taken into account, it is difficult to spatio-temporally comprehend the places in which the real person and its imposter exist. Inevitably, the real person and its imposter have to be in mutually different possible worlds as defined by possible worlds semantics. This leads into the conclusion that after the onset of Capgras syndrome, the patient and the imposter are in a possible world that is different from the possible world to which the real person belongs. In the case presented herein, the patient repeatedly talked about how difficult it was to get access to the real person. If the patient was separated by space and time from the real person, his difficulty in getting access should have been only a matter of relativity. On the contrary, it is quite likely that what the patient really wanted to express is the fundamental impossibility of access that exists between two individuals who belong to mutually different possible worlds.
authors.affiliation: School of Health Sciences, Faculty of Medicine, Akita University.
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Niiyama
mesh_terms: D000368:Aged; D002194:Capgras Syndrome / Q000523:psychology*; D003702:Delusions; D006801:Humans; D008297:Male