Coltheart, M.
Centre for Cognition and its Disorders, Macquarie University, Sydney, Australia
According to the two-factor theory of delusion, to explain any particular form of delusional one needs to provide answers to just two questions. First: why did a belief with this particular content ever occur to the deluded person in the first place (for example, what made a patient with Cotard delusion ever entertain the thought that his wife has vanished and been replaced by an identical-looking impostor)? Second: once the delusional idea does come to mind, why is it accepted as a belief, rather than rejected (as it should be, given that most delusional beliefs are so bizarre, and given that the patient's family, friends and clinicians are all denying the truth of the belief)?
An account will be given of how this theory is applied to the explanation of a variety of delusions will be given, and current difficulties for this account will be discussed.