By Olivia Scheck
When a person is prone to making claims that are clearly inconsistent with facts about the world, we say that he is crazy. His brain has gone haywire, and he is no longer responsive to reason. However, when the person making a plainly unrealistic claim is otherwise rational, this simplistic explanation may seem particularly unsatisfactory. A person suffering from Capgras Delusion, for instance, may show no other signs of mental illness, and yet he insists that someone in his life (usually a close family member) has been replaced by an imposter. Similarly, the Cotard patient may seem perfectly normal, aside from his assertion that he is actually dead and rotting before your eyes. These fascinating cases of monothematic delusion have, despite their rarity, prompted a number of psychologists and philosophers to wonder, “What is the nature of delusion?”
Shaun Gallagher, a professor of philosophy at the University of Central Florida and the Editor ofPhenomenology and the Cognitive Sciences, has contributed to this growing literature. In his article, “Delusional Realities,” to appear in a forthcoming issue ofPsychiatry as Cognitive Science, Gallagher suggests several inadequacies of previous accounts and offers his own characterization of delusion, which conceives of the delusional individual as existing in “multiple realities.” I had the opportunity to speak with Professor Gallagher last Thursday, following a talk he gave at the Whitney Humanities Center at Yale University; I offer excerpts from our discussion here.
First, though, a little background on existing theories and a brief synopsis of Gallagher’s Multiple Realities Hypothesis:
Traditionally, accounts of delusion have fallen into one of two categories: top-down or bottom-up. Top-down accounts suggest that delusions result from disturbances in high-level understanding. The philosopher and UC Berkeley professor, John Campbell, for example, invokes Wittgentein’s notion of a “framework proposition” – an axiom that is implicitly assumed and never answerable to empirical facts – to characterize delusion. On Campbell’s view, delusions arise when an erroneous belief – such as, “my mother is an imposter” – takes on this type of incontrovertible epistemological status.
On the other hand, according to bottom-up accounts, delusions are not caused by false beliefs, but rather false perceptions. The popular neurologist Vilayanur Ramachandran gives a clear and entertaining bottom-up explanation for Capgras in his TED talk, “A Journey to the Center of Your Mind.” He believes that the Capgras patient’s assertion that his mother has been replaced by an imposter is, in fact, a rational metacognitive response to a peculiar perception. Specifically, Ramachandran proposes that the Capgras patient experiences an abnormal emotional response when looking at his mother, which results from a communicative disconnect between the area of the brain associated with face recognition and the its emotional center. Responding to this lack of affective response, the patient infers that his mother has been replaced by an imposter.