Stanford Encyclopedia Entry on Delusions.

How many factors, i.e. departures from normality, are necessary to explain a delusion? Maher’s classic one-factor theory argues that the only factor is the patient’s anomalous experience, and a delusion arises as a normal explanation of this experience. The more recent two-factor theory, on the other hand, contends that a second factor is also needed, with reasoning abnormality being a potential candidate, and a delusion arises as an abnormal explanation of the anomalous experience. In the past few years, although there (...) has been an increasing number of scholars offering a variety of arguments in defence of Maher’s one-factor theory, these arguments have not been adequately addressed by two-factor theorists. This paper aims to address this gap by critically examining the arguments on three crucial issues: the intelligibility of delusions, the dissociation between anomalous experiences and delusions, and the empirical evidence of a second factor. I will argue that the Maherian notion of anomalous experience is not sufficient for explaining delusions and the two-factor theory is on the right track in its search for the missing factor in the aetiology of delusions. (shrink)

Brains, it has recently been argued, are essentially prediction machines. They are bundles of cells that support perception and action by constantly attempting to match incoming sensory inputs with top-down expectations or predictions. This is achieved using a hierarchical generative model that aims to minimize prediction error within a bidirectional cascade of cortical processing. Such accounts offer a unifying model of perception and action, illuminate the functional role of attention, and may neatly capture the special contribution of cortical processing to (...) adaptive success. This target article critically examines this approach, concluding that it offers the best clue yet to the shape of a unified science of mind and action. Sections 1 and 2 lay out the key elements and implications of the approach. Section 3 explores a variety of pitfalls and challenges, spanning the evidential, the methodological, and the more properly conceptual. The paper ends (sections 4 and 5) by asking how such approaches might impact our more general vision of mind, experience, and agency. (shrink)

In recent times, explanations of the Capgras delusion have tended to emphasise the cognitive dysfunction that is believed to occur at the second stage of two-stage models. This is generally viewed as a response to the inadequacies of the one-stage account. Whilst accepting that some form of cognitive disruption is a necessary part of the aetiology of the Capgras delusion, I nevertheless argue that the emphasis placed on this second-stage is to the detriment of the important role played by the (...) phenomenology underlying the disorder, both in terms of the formation and maintenance of the delusional belief. This paper therefore proposes an interactionist two-stage model in which the phenomenal experience of the Capgras patient is examined, emphasised, and its relation to top-down processing discussed. (shrink)

This paper contrasts an interactionist account of delusional misidentification with more traditional one- and two-stage models. Unlike the unidirectional nature of these more traditional models, in which the aetiology of the disorder is said to progress from a neurological disruption via an anomalous experience to a delusional belief, the interactionist account posits the interaction of top-down and bottom-up processes to better explain the maintenance of the delusional belief. In addition, it places a greater emphasis on the patient’s underlying phenomenal experience (...) in accounting for the specificity of the delusional content. The role played by patient phenomenology is examined in light of Ratcliffe’s recent phenomenological account. Similarities and differences are discussed. The paper concludes that a purely phenomenological account is unable to differentiate between non-delusional patient groups, who have what appear to be equivalent phenomenal experiences to patients suffering from delusional misidentification but without the delusional belief, and delusional groups, something the interactionist model is able to do. (shrink)

ABSTRACTEmpiricists about monothematic delusion formation agree that anomalous experience is a factor in the formation of these attitudes, but disagree markedly on which further factors need to be specified. I argue that epistemic innocence may be a unifying feature of monothematic delusions, insofar as a judgment of epistemic innocence to this class of attitudes is one that opposing empiricist accounts can make. The notion of epistemic innocence allows us to tell a richer story when investigating the epistemic status of monothematic (...) delusions, one which resists the trade-off view of pragmatic benefits and epistemic costs. Though monothematic delusions are often characterized by appeal to their epistemic costs, they can play a positive epistemic role, and this is a surprising conclusion on which, so I argue, all empiricists can agree. Thus, I show that all empiricists have the notion of epistemic innocence at their disposal. (shrink)

In his recent book Delusions and Beliefs, Kengo Miyazono offers a thoroughgoing defence of delusions as biologically malfunctioning beliefs, greatly elaborating on his earlier defence of this view. Miyazono has it that delusions have biological doxastic functions, and that delusions involve direct or indirect malfunctions of this kind. In this short piece, I focus on Miyazono’s defence of a two-factor approach to delusion formation as it appears in Chapter Four. Miyazono approaches his discussion of the debate between one- and two-factor (...) theories having already defended the key thesis of the book: that delusions are malfunctioning beliefs. Of course, that thesis might be thought to mesh nicely with the two-factor theorist’s claim that there is a cognitive abnormality present in delusion formation or maintenance. However, I will discuss Miyazono’s defence of the two-factor position in isolation from its role in his overall account of delusion. Miyazono abstracts away from the particulars of Max Coltheart’s two-factor view, and takes himself to be investigating the plausibility of two-factor theories without the specific commitments of Coltheart’s view. Miyazono also captures under the two-factor heading theories which locate the second factor in belief maintenance rather than just in belief formation. He puts forward a new argument for a two-factor approach which goes via inference to the best explanation. I begin by arguing that Miyazono’s starting motivation for a two-factor approach rests on a misrepresentation of the one-factor approach. Then, I turn to the four components of Miyazono’s inference to the best explanation argument, and argue that in each case, we do not have grounds for positing a second factor. (shrink)

Circumscribed delusional beliefs can follow brain injury. We suggest that these involve anomalous perceptual experiences created by a deficit to the person's perceptual system, and misinterpretation of these experiences due to biased reasoning. We use the Capgras delusion (the claim that one or more of one's close relatives has been replaced by an exact replica or impostor) to illustrate this argument. Our account maintains that people voicing this delusion suffer an impairment that leads to faces being perceived as drained of (...) their normal affective significance, and an additional reasoning bias that leads them to put greater weight on forming beliefs that are observationally adequate rather than beliefs that are a conservative extension of their existing stock. We show how this position can integrate issues involved in the philosophy and psychology of belief, and examine the scope for mutually beneficial interaction. (shrink)

Maher proposed in 1974 that schizophrenic delusions are hypotheses formed to explain anomalous experiences. He stated that they are “rational, given the intensity of the experiences that they are developed to explain.” Two-factor theorists of delusion criticized Maher’s theory because 1) it does not explain why some patients with anomalous experiences do not develop delusions, and 2) adopting and adhering to delusional hypotheses is irrational, considering the totality of experiences and patients’ other beliefs. In this paper, the notion of the (...) intensity of experience is reappraised to uphold Maher’s basic conception. Regarding 1), I propose that differences in the intensity of anomalous experience are vital to whether the patient forms delusions, while partially reforming his rationality claim regarding 2). Although adopting delusions is irrational, it is inevitable and excusable, given the intensity of the patient’s anomalous experience. With the aid of this notion, it is maintained that anomalous experience is sufficient for the development of delusions, at least in some cases of schizophrenia. Compared to other theories of schizophrenic delusion, Maher’s theory, which embraces the notion of intensity of experience, better explains why such irrational mental states as delusions develop from anomalous experiences, and why delusional patients persist in believing specific thematic content. (shrink)

My response to the preceding essays begins with some preliminaries about my terminology, approach, and conception of rationality as a regulative ideal. I then comment on the Murphy's discussion about normal religious belief and religious delusions, and on causal assumptions challenged by Langdon's folies à deux. Responding to Gerrans's imagination-based account of delusion and Hohwy's discussion of illusions, I next try to envision what both doxastic and imagination-based approaches might have overlooked by asking whether there can be delusional feelings. Final (...) comments address the place of phenomenology within Coltheart's two-factor theorizing. (shrink)

Monothematic delusions involve a single theme, and often occur in the absence of a more general delusional belief system. They are cognitively atypical insofar as they are said to be held in the absence of evidence, are resistant to correction, and have bizarre contents. Empiricism about delusions has it that anomalous experience is causally implicated in their formation, whilst rationalism has it that delusions result from top down malfunctions from which anomalous experiences can follow. Within empiricism, two approaches to the (...) nature of the abnormality/abnormalities involved have been touted by philosophers and psychologists. One-factor approaches have it that monothematic delusions are a normal response to anomalous experiences whilst two-factor approaches seek to identify a clinically abnormal pattern of reasoning in addition to anomalous experience to explain the resultant delusion. In this paper we defend a one-factor approach. We begin by making clear what we mean by atypical, abnormal, and factor. We then identify the phenomenon of interest and overview one and two-factor empiricism about its formation. We critically evaluate the cases for various second factors, and find them all wanting. In light of this we turn to our one-factor account, identifying two ways in which ‘normal response’ may be understood, and how this bears on the discussion of one-factor theories up until this point. We then conjecture that what is at stake is a certain view about the epistemic responsibility of subjects with delusions, and the role of experience, in the context of familiar psychodynamic features. After responding to two objections, we conclude that the onus is on two-factor theorists to show that the one-factor account is inadequate. Until then, the one-factor account ought to be understood as the default position for explaining monothematic delusion formation and retention. We don’t rule out the possibility that, for particular subjects with delusions there may be a second factor at work causally implicated in their delusory beliefs but, until the case for the inadequacy of the single factor is made, the second factor is redundant and fails to pick out the minimum necessary for a monothematic delusion to be present. (shrink)

The condition known as Multiple Personality Disorder (MPD) or Dissociative Identity Disorder (DID) is metaphysically strange. Can there really be several distinct persons operating in a single body? Our view is that DID sufferers are single persons with a severe mental disorder. In this paper we compare the phenomenology of dissociation between personality states in DID with certain delusional disorders. We argue both that the burden of proof must lie with those who defend the metaphysically extravagant Multiple Persons view and (...) that there is little theoretical motivation to yield to that view in light of the fact that the core symptoms of DID bear remarkable similarity to the symptoms of these other disorders where no such extravagance is ever seriously entertained. (shrink)

This article examines the supposedly incomprehensibility of schizophrenic delusions. According to the contemporary classificatory systems (DSM-IV-TR and ICD-10), some delusions typically found in schizophrenia are considered bizarre and incomprehensible. The aim of this article is to discuss the notion of understanding that deems these delusions incomprehensible and to see if it is possible to comprehend these delusions if we apply another notion of understanding. First, I discuss the contemporary schizophrenia definitions and their inherent problems, and I argue that the notion (...) of incomprehensibility in these definitions rests heavily on Jaspers’ notions of understanding and empathy. Secondly, I discuss two Wittgensteinian attempts to comprehend bizarre delusions: (a) Campbell’s proposal to conceive delusions as framework propositions and (b) Sass’s suggestion to interpret delusions in the light of solipsism. Finally, I discuss the phenomenological conception of schizophrenia, which conceives delusion formation as resulting from alterations of the structure of experiencing and from underlying self-disorders. I argue that although a psychological understanding that seeks to grasp meaning in terms of motivations, desires, and other more straightforward psychological connections between mental states is impossible in schizophrenia, we can in fact have a philosophical understanding of the schizophrenic world and of the emergence of delusions typically found in schizophrenia. (shrink)

The distinction of „understanding“ and „explaining“, formulated by Karl Jaspers in his „General Psychopathology“, has had a lasting effect on psychiatry. As a result, phenomenological, hermeneutic, or psychodynamic approaches have often been accorded only descriptive or epiphenomenal status, while the actual causes of mental illness have been sought in neurobiologically or genetically based explanations. In contrast, this paper defends the explanatory role of understanding and phenomenological approaches. To this end, two levels of explanation are distinguished and shown to be equally (...) justified in principle, namely, motivational explanation at the macro-level and physical explanation at the micro-level. The actual causal role of motivational, i.e., understandable connections is then demonstrated by means of a conception of circular causality, which includes downward causality. Finally, the explanatory role of phenomenological analyses is also shown in psychotic disorders that refuse motivational understanding, using the example of schizophrenic delusion. (shrink)

Nietzsche’s cardinal ideas - God is Dead, Übermensch and Eternal Return of the Same - are approached here from the perspective of psychiatric phenomenology rather than that of philosophy. A revised diagnosis of the philosopher’s mental illness as manic-depressive psychosis forms the premise for discussion. Nietzsche conceived the above thoughts in close proximity to his first manic psychotic episode, in the summer of 1881, while staying in Sils-Maria (Swiss Alps). It was the anniversary of his father’s death, and also of (...) the break-up of his friendship with Wagner, the most important relationship in his life. Despite having been acquainted with these ideas from reading philosophy and literature, Nietzsche created them de novo and imbued them with very personal meaning. Surprisingly, he never defined or explained his cardinal thoughts in his published writings, perhaps because rationally he could not. A resultant hermeneutic vacuum provoked an avalanche of interpretations in secondary literature. But could these ideas be delusions? A current definition of delusion is challenged, and an attempt is made at a limited comparison between delusion, scientific/philosophical doctrine and poetic creation. It is also argued that psychosis is a way of re-living trauma, and delusions can therefore be seen as a form of reasoning that helps to make sense of the world in a state of psychotic disintegration. Far from being false beliefs, delusions are a true expression of one’s innermost feelings and pain, albeit indirectly. The relationship between early parental loss and repeated trauma, psychosis and creativity is also explored. Indo-Pacific Journal of Phenomenology , Volume 8, Edition 1 May 2008. (shrink)