This paper explores the two-factor theoretical model currently widely used to provide an explanatory analysis of the delusions that regularly accompany neurological disease or damage. The model hypothesizes a combination of an experiential factor – a strange or untoward experience – and a cognitive factor, such as an impairment of reasoning. The two-factor model has been devised formonothematicdelusions that are usually manifested in a single, implausible idea. These have to be distinguished from the more elaborated,polythematicdelusions that are found in psychiatry. (...) Psychiatric delusions exceed neurological ones in frequency and, often, semantic complexity. This text offers a preliminary clarification of underlying assumptions about the breadth, terminology and presuppositions of two-factor theorizing, exploring its potential application to psychiatric delusions. (shrink)