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  • The Phenomenology of Abnormal Belief: A Philosophical and Psychiatric Inquiry
  • Edgar Jones (bio)

Delusion, one of the key symptoms of madness, has defied definition, being described as a belief, an incomprehensible phenomenon, and as an empty speech act. It was hypothesized that a detailed investigation of its characteristics would aid categorization and help to understand what makes it different from everyday forms of belief. Philosophical texts (principally those of Locke, Hume, Newman, and James, together with more recent writings from “folk psychology”) were surveyed to elicit belief characteristics which could then be introduced to established clinical tests. Seven qualities drawn from the philosophy of mind were added to five borrowed from empirical psychology in an attempt to broaden the investigation of delusion. These revealed significant differences between delusions held by schizophrenics, the overvalued ideas of anorectics, and the religious beliefs of a normal population of church attendees. This study shows not only that these phenomena are capable of detailed analysis, but that ideas taken from philosophy can be profitably reapplied to complex questions of descriptive psychopathology.


abnormal belief, delusion, overvalued idea, faith, folk psychology, initial and derived beliefs, David Hume, William James


Since time immemorial,” argued Karl Jaspers (1883–1961), “delusion has been taken as the basic characteristic of madness. To be mad was to be deluded, and indeed what constitutes a delusion is one of the basic problems of psychopathology” (1963 [1913], 93). Bizarre beliefs, or acceptable beliefs supported by bizarre evidence, continue to guide clinicians in identifying psychosis. Delusion, therefore, has remained an important psychiatric symptom. Yet despite this significance, it has defied unambiguous definition. Clinicians have described it in a variety of ways. For Jaspers it was “psychologically irreducible,” a direct and intrusive form of new meaning, while Bleuler thought that it was a belief of great power, driven by strong emotion. More recently, delusion has been categorized as a false belief, a defective reason for action, and even as an empty speech act which adopts the disguise of a belief. Ideas drawn from philosophy have proved valuable in clarifying psychiatric problems, as demonstrated by Marshall’s re-examination of the nature of need in the design of a Care Assessment Schedule (Marshall 1994). Belief has long been the subject of philosophical analysis, and it is hypothesized that concepts borrowed from this discipline might unlock some of the problems surrounding a satisfactory definition of delusion. Furthermore, the processes at work in the creation or maintenance of beliefs might provide insights into how delusions form and continue to [End Page 1] be held in the face of contradictory propositions. Accordingly, philosophical writings have been surveyed to elicit testable questions about the features of delusion and other related phenomena, such as the overvalued idea and the obsession.

Problems of Definition

Clinical Descriptions of Delusion

Emil Kraepelin (1856–1926) identified delusion as a major symptom of dementia praecox, especially of the paranoid type. Organizing delusion by content into six categories (ideas of sin, ideas of persecution, ideas of influence, exalted ideas, sexual ideas, and ideas of reference), Kraepelin offered no causal explanation, though he acknowledged the likely role of aberrant perceptual experiences in their formation (1919, 32). Influenced by psychoanalytic concepts, Eugen Bleuler (1857–1939) divided delusion into two classes: “basic” and “elaborative.” The former he defined as a central theme or belief driven by a powerful affect which often seemed to emerge “primordially from the unconscious in their complete and finished form” (1950, 135). “Delusional elaborations,” by contrast, Bleuler categorized as errors of logical thought, a consequence of loosening of association, and were motivated, in part, by the subject’s need to find an explanation for the bizarre situation in which he found himself.

Jaspers scarcely referred to belief in his General Psychopathology and wrote of “delusion proper” in terms not of “considered interpretations but direct experiences of meaning, while perception itself remains normal and unchanged” (1963 [1913], 99–100). Jaspers argued that delusion formation was a two-stage process involving the input of new “sensory material” followed by an immediate and intrusive meaning. This was an adaptation of the Kantian two-stem theory of knowledge of form and content, the sensory material being the incoming...