As I suggested in my previous post, we sometimes have the impression that people do not fully endorse their delusions. In some circumstances, they don’t seem to act in a way that is consistent with genuinely believing the content of their delusions. For instance, a person with persecutory delusions may accuse the nurses in the hospital of wanting to poison him, and yet eat happily the food he’s given; a person with Capgras delusion may claim that his wife has been replaced by an impostor but do nothing to look for his wife or make life difficult for the alleged “impostor”.
Some philosophers, such as Shaun Gallagher, Keith Frankish and Greg Currie, have argued on the basis of this phenomenon (which is sometimes called “double bookkeeping”) that delusions are not beliefs. They assume that action guidance is a core feature of beliefs and maintain that, if delusions are not action guiding, then they are not beliefs. Although I have sympathies with the view that action guidance is an important aspect of many of our beliefs, I find the argument against the belief status of delusions a bit too quick.
First, as psychiatrists know all too well, delusions lead people to act. People who believe that they are dead Cotard delusion may become akinetic, and may stop eating and washing as a result. People who suffer from delusions of guilt, and believe they should be punished for something evil they have done, engage in self-mutilation. People who falsely believe they are in danger (persecutory delusions) avoid the alleged source of danger and adopt so-called “safety behaviours”. The list could go on. In general it isn’t true that delusions are inert.
Second, when delusions don’t cause people to act, a plausible explanation is that the motivation to act is not acquired or not sustained. Independent evidence suggests that people with schizophrenia have meta-representational deficits, flattened affect and emotional disturbances, which can adversely impact on motivation. Moreover, as Matthew Broome argues, the physical environment surrounding people with the delusion doesn’t support the action that would ensue from believing the content of the delusion. The content of one’s delusion may be so bizarre (e.g., “There’s a nuclear reactor in my belly”) that no appropriate action presents itself. The social environment might be equally unsupportive. One may stop talking about one’s delusion and acting on it to avoid incredulity or abuse from others.
My view that delusions are continuous with ordinary beliefs is not challenged by these considerations: maybe to a lesser extent than people with delusions, we all act in ways that are inconsistent with some of the beliefs we report - when we’re hypocritical - and we may fail to act on some of our beliefs for lack of motivation - when we’re weak-willed.