Delusions and Other Beliefs

AbstractThe difficulty of distinguishing between delusions and non-pathological beliefs has taxed some of the greatest minds in psychiatry. This chapter argues that this question cannot be resolved without first having an understanding of what is involved in holding an ordinary belief. Although we should not assume that ordinary-language words such as ‘belief’ will correspond with a specific psychological mechanism or process, sufficient evidence is available from diverse areas of psychology to reach some conclusions about what happens when someone ‘believes’ something. Beliefs are propositions about the world that are generated dynamically, often during interactions with other people, and therefore depend on the human capacity for language. Although many beliefs are mundane, it is possible to identify a class of master interpretive systems that includes political ideologies and religious belief systems, which are highly resistant to challenge and capable of generating considerable emotion. These systems seem to depend not only on the ability to generate propositions about the world but also on implicit cognitive processes that are related to fundamental biological and social needs, for example the need to avoid contagion, the need to form close intimate relationships or the need to avoid out-groups. Delusions share many of the properties of master interpretive systems but differ because they are idiosyncratic. They may arise when individuals are very isolated or if they lack the cognitive tools to function effectively in groups. Further progress in understanding delusions is likely to be made if research is informed by findings from political psychology and the psychology of religion.