In order to explain delusional beliefs, one must first consider what factors should be included in a theory of delusion. Unlike a one-factor theory, a two-factor theory of delusion argues that not only anomalous experience (the first factor) but also an impairment of the belief-evaluation system (the second factor) is required. Recently, two-factor theorists have adopted various Bayesian approaches in order to give a more accurate description of delusion formation. By reviewing the progression from a one-factor theory to (...) a two-factor theory, I argue that in light of the second factor’s requirements, different proposed impairments can be unified within a consistent belief-evaluation system. Under this interpretation of the second factor, I further argue that the role of a mechanism responsible for detecting bizarreness is wrongly neglected. I conclude that the second factor is a compound system which consists of differing functional parts, one of which functions to detect bizarreness in different stages of delusion; moreover, I hold that the impairment can be one or several of these functional parts. (shrink)

Philosophers have been long interested in delusional beliefs and in whether, by reporting and endorsing such beliefs, deluded subjects violate norms of rationality (Campbell 1999; Davies & Coltheart 2002; Gerrans 2001; Stone & Young 1997; Broome 2004; Bortolotti 2005). So far they have focused on identifying the relation between intentionality and rationality in order to gain a better understanding of both ordinary and delusional beliefs. In this paper Matthew Broome and I aim at drawing attention to the extent (...) to which deluded subjects are committed to the content of their delusional beliefs, that is, to whether they can be regarded as authors of their beliefs (Moran 2001). We consider several levels of commitment one can have to a reported belief, delusional or otherwise, and we distinguish between _ownership_ and _authorship_ of beliefs (Gallagher 2000). After examining some examples of belief authoring (or lack thereof) in psychopathology, we argue that there is no straight-forward and unitary answer to the question whether deluded subjects author their beliefs. Nevertheless, introducing the notion of authorship in the debate can significantly contribute to the philosophical literature on the rationality of delusions and can also have important implications for diagnosis and therapy in psychiatry. (shrink)

Delusional beliefs have sometimes been considered as rational inferences from abnormal experiences. We explore this idea in more detail, making the following points. Firstly, the abnormalities of cognition which initially prompt the entertaining of a delusional belief are not always conscious and since we prefer to restrict the term “experience” to consciousness we refer to “abnormal data” rather than “abnormal experience”. Secondly, we argue that in relation to many delusions (we consider eight) one can clearly identify what (...) the abnormal cognitive data are which prompted the delusion and what the neuropsychological impairment is which is responsible for the occurrence of these data; but one can equally clearly point to cases where this impairments is present but delusion is not. So the impairment is not sufficient for delusion to occur. A second cognitive impairment, one which impairs the ability to evaluate beliefs, must also be present. Thirdly (and this is the main thrust of our chapter) we consider in detail what the nature of the inference is that leads from the abnormal data to the belief. This is not deductive inference and it is not inference by enumerative induction; it is abductive inference. We offer a Bayesian account of abductive inference and apply it to the explanation of delusional belief. (shrink)

Folie à deux is the transference of delusional ideas from one 'primary' individual to one or more 'secondary' individuals (Lasègue & Falret, 1877). However, it is difficult to investigate experimentally because often only one patient is identified as delusional. We investigated whether hypnosis could model the experiences of the secondary in this delusion. Our primary was a confederate, who displayed two delusional beliefs and attempted to transmit them to hypnotised subjects. We manipulated the status of the confederate (...) so that they were portrayed as either "credible" or merely "interesting". Many high hypnotisable individuals adopted the confederate's beliefs and confabulated evidence in support of them. Also, subjects who interacted with a credible confederate extended their delusions beyond those displayed by the confederate. We discuss the strengths and limitations of this approach and suggest ways to improve the validity of this model. (shrink)

The Capgras delusion is a condition in which a person believes that an imposter has replaced some close friend or relative. Recent theorists have appealed to Bayesianism to help explain both why a subject with the Capgras delusion adopts this delusional belief and why it persists despite counter-evidence. The Bayesian approach is useful for addressing these questions; however, the main proposal of this essay is that Capgras subjects also have a delusional conception of epistemic possibility, more specifically, (...) they think more things are possible, given what is known, than non-delusional subjects do. I argue that this is a central way in which their thinking departs from ordinary cognition and that it cannot be characterized in Bayesian terms. Thus, in order to fully understand the cognitive processing involved in the Capgras delusion, we must move beyond Bayesianism. 1 The Simple Bayesian Model2 Anomalous Evidence and the Capgras Delusion3 Impaired Reasoning4 Setting Priors5 Epistemic Modality6 Delusions of Possibility7 Delusions of Possibility in Different Contexts8 How Many Factors? (shrink)

In this paper we address the ethics of adopting delusional beliefs and we apply consequentialist and deontological considerations to the epistemic evaluation of delusions. Delusions are characterised by their epistemic shortcomings and they are often defined as false and irrational beliefs. Despite this, when agents are overwhelmed by negative emotions due to the effects of trauma or previous adversities, or when they are subject to anxiety and stress as a result of hypersalient experience, the adoption of a delusional (...) belief can prevent a serious epistemic harm from occurring. For instance, delusions can allow agents to remain in touch with their environment overcoming the disruptive effect of negative emotions and anxiety. Moreover, agents are not blameworthy for adopting their delusions if their ability to believe otherwise is compromised. There is evidence suggesting that no evidence-related action that would counterfactually lead them to believe otherwise is typically available to them. The lack of ability to believe otherwise, together with some other conditions, implies that the agents are not blameworthy for their delusions. The examination of the epistemic status of delusions prompts us to acknowledge the complexity and contextual nature of epistemic evaluation, establish connections between consequentialist and deontological frameworks in epistemology, and introduce the notion of epistemic innocence into the vocabulary of epistemic evaluation. (shrink)

INTRODUCTION: In accounts of the two-factor theory of delusional belief, the second factor in this theory has been referred to only in the most general terms, as a failure in the processes of hypothesis evaluation, with no attempt to characterise those processes in any detail. Coltheart and Davies attempted such a characterisation, proposing a detailed eight-step model of how unexpected observations lead to new beliefs based on the concept of abductive inference as introduced by Charles Sanders Peirce. METHODS: (...) In this paper, we apply that model to the explanation of various forms of delusional belief. RESULTS: We provide evidence that in cases of delusion there is a specific failure of the seventh step in our model: the step at which predictions from hypotheses are considered in the light of relevant evidence. CONCLUSIONS: In the two-factor theory of delusional belief, the second factor consists of a failure to reject hypotheses in the face of disconfirmatory evidence. (shrink)

Numerous studies of the beliefs of people with anorexia nervosa (AN) suggest that a subset of such individuals may experience delusions. We first describe what makes a belief delusional and conclude that such characteristics can be appropriately applied to some beliefs of people with AN. Next, we outline how delusional beliefs may relate to the broader psychopathological process in AN, including: (1) they may be epiphenomenal; (2) they may be an initial partial cause of AN; (3) they (...) may be caused by aspects of AN; or (4) they may be sustaining causes, possibly involved in reciprocal causal relations with aspects of AN. We argue that there is good reason to believe that delusional beliefs of people with AN are not merely epiphenomenal, but rather that they’re causally connected to AN. Because of this, empirical studies can be designed to test for the presence of causal relations. We describe how these studies should be designed. The results of such studies have important implications for understanding the experience of individuals with AN and for the treatment of AN. We outline these implications. (shrink)

ABSTRACTThis article intends to reconsider the epistemological status of delusional beliefs on the basis of Wittgenstein’s conception of certainty. Several works over the last two decades have compared delusional beliefs with so-called hinge propositions, which – according to Wittgenstein – function as expressions of objective certainty. This gives rise to a paradox. On the one hand, delusions are compatible to Wittgensteinian certainties in some respects; on the other hand, they contradict beliefs shared by other members of the community, (...) which makes them different from ‘normal’ certainties. In order to address this issue, I use Moyal-Sharrock’s taxonomy of hinge propositions. This taxonomy allows one to distinguish between different types of hinge propositions; all types share the same features, but these features are manifested in a variety of ways. Thus, delusional beliefs might also be regarded as constituting a specific type of hinge propositions. This move makes it possible to resolve the paradox and to identify the special epistemic features of delusional beliefs. (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)

Richard Mullen and Grant Gillett (2014) decry the oversimplifications that accompany ‘doxastic’ analyses of delusion analogizing them to belief states; particularly, they object to the recent elevation to the status of paradigmatic the ordinary beliefs often understood, in Bayesian terms, as probabilistic estimates of empirical facts. Such an approach ignores the significance of the delusion for the individual, they emphasize, neglecting the delusional person’s conceptions of self and identity in relation to the world. In support of their plea (...) for a broader, more nuanced, and more clinically and existentially sensitive understanding of delusion, Mullen and Gillett enumerate drawbacks to the doxastic view not .. (shrink)

In philosophy, psychiatry, and cognitive science, definitions of clinical delusions are not based on the mechanisms responsible for the formation of delusions, since there is no consensus yet on what causes delusions. Some of the defining features of delusions are epistemic and focus on whether delusions are true, justified, or rational, as in the definition of delusions as fixed beliefs that are badly supported by evidence. Other defining features of delusions are psychological and focus on whether delusions are harmful, as (...) in the definition of delusions as beliefs that disrupt good functioning. Even if the epistemic features go some way towards capturing what otherwise different instances of clinical delusions have in common, they do not succeed in distinguishing delusions as a clinical phenomenon from everyday irrational beliefs. Focusing on the psychological features is a more promising way to mark the difference between clinical and non-clinical irrational beliefs, but there is wide variability in the extent to which delusions are psychologically harmful, and some everyday irrational beliefs can affect functioning in similarly negative ways. In this chapter we consider three types of belief that share similar epistemic features and exhibit variation with respect to how psychologically harmful they are: (1) delusions of thought insertion, (2) alien abduction beliefs, and (3) self-enhancing beliefs. In the light of the similarities and differences among these cases, we highlight the difficulty in providing an answer to what makes an irrational belief delusional. (shrink)

In philosophy, psychiatry, and cognitive science, definitions of clinical delusions are not based on the mechanisms responsible for the formation of delusions. Some of the defining features of delusions are epistemic and focus on whether delusions are true, justified, or rational, as in the definition of delusions as fixed beliefs that are badly supported by evidence). Other defining features of delusions are psychological and they focus on whether delusions are harmful, as in the definition of delusions as beliefs that disrupt (...) good functioning. Even if the epistemic features go some way towards capturing what otherwise different instances of clinical delusions have in common, they do not succeed in distinguishing delusions as a clinical phenomenon from everyday irrational beliefs. Focusing on the psychological features is a more promising way to mark the difference between clinical and non-clinical irrational beliefs, but there is wide variability in the extent to which delusions are psychologically harmful, and some everyday irrational beliefs can affect functioning in similarly negative ways. In this chapter we consider three types of belief that share similar epistemic features and exhibit variation with respect to how psychologically harmful they are: (1) delusions of thought insertion, (2) alien abduction beliefs, and (3) self-enhancing beliefs. In the light of the similarities and differences between these cases, we highlight the difficulty in providing an answer to what makes an irrational belief delusional. (shrink)

In both cognitive science and philosophy, many theorists have recently appealed to a predictive processing framework to offer explanations of why certain individuals form delusional beliefs. One aim of this essay will be to illustrate how one could plausibly develop a predictive processing account in different ways to account for the onset of different kinds of delusions. However, the second aim of this essay will be to discuss two significant limitations of the predictive processing framework. First, I shall draw (...) on the structure of explanatory why-questions to argue that predictive processing theories can only partially explain the formation of delusional beliefs. Second, I shall argue that predictive processing theories cannot explain how implausible delusional hypotheses are generated. Yet understanding why an agent even generates a delusional hypothesis is a crucial step to understanding why she eventually comes to believe it. The final section of the essay presents three alternative ways the process of hypothesis generation might be functionally divergent in cases of delusional cognition. (shrink)

Does the formation of delusions involve abnormal reasoning? According to the prominent ‘two-factor’ theory of delusions (e.g. Coltheart, 2007), the answer is yes. The second factor in this theory is supposed to affect a deluded individual's ability to evaluate candidates for belief. However, most published accounts of the two-factor theory have not said much about the nature of this second factor. In an effort to remedy this shortcoming, Coltheart, Menzies and Sutton (2010) recently put forward a Bayesian account of (...) inference in delusions. I outline some criticisms of this important account, and sketch an alternative account of delusional inference that, I argue, avoids these criticisms. Specifically, I argue that the second factor in delusion formation involves a systematic deviation from Bayesian updating, a deviation that may be characterized as a bias towards ‘explanatory adequacy’. I present a numerical model of this idea and show that my alternative account is broadly consistent with prominent prediction error models of delusion formation (e.g. Corlett, Murray et al., 2007). (shrink)

Delusions are deeply evidence-resistant. Patients with delusions are unmoved by evidence that is in direct conflict with the delusion, often responding to such evidence by offering obvious, and strange, confabulations. As a consequence, the standard view is that delusions are not evidence-responsive. This claim has been used as a key argumentative wedge in debates on the nature of delusions. Some have taken delusions to be beliefs and argued that this implies that belief is not constitutively evidence-responsive. Others hold fixed (...) the evidenceresponsiveness of belief and take this to show that delusions cannot be beliefs. Against this common assumption, I appeal to a large range of empirical evidence to argue that delusions are evidence-responsive in the sense that subjects have the capacity to respond to evidence on their delusion in rationally permissible ways. The extreme evidence-resistance of delusions is a consequence of powerful masking factors on these capacities, such as strange perceptual experiences, motivational factors, and cognitive biases. This view makes room for holding both that belief is constitutively evidence-responsive and that delusions are beliefs, and it has important implications for the study and treatment of delusions. (shrink)

INTRODUCTION: Delusional misidentification syndromes (DMS) are a group of psychopathological experiences occurring in psychosis, involving the misidentification of a person or place. DMS are often accompanied by hostility towards the object of delusional misidentification. This is of a particular concern in perinatal mental illness due to the potential disruption of the mother-infant bond, and risk of neglect, violence, or infanticide towards a misidentified child. This review aimed to collate all published cases of DMS in postpartum psychosis to further (...) understand how these syndromes present in perinatal mental illness. METHODS: In August 2021, an online database search was conducted using PubMed, MEDLINE, PsycINFO, CINAHL, and Embase to identify all publications reporting DMS in the perinatal period. RESULTS: Nine papers were included in the review involving 8 case reports of Capgras syndrome and one case series involving 4 cases of Fregoli syndrome. Three cases identified organic pathology, which may have contributed to the presentation. The most common subject of misidentification was the patient’s husband (n = 7), followed by their baby (n = 6), hospital staff (n = 4), other family members (n = 3), and self (n = 1). Five cases remark on the impact of perinatal illness on the maternal-infant bond, of which four result in the mother being unwilling to care for the infant as the result of their delusional beliefs. CONCLUSION: This is the first systematic review of the literature in this field. Although small in number, these cases reveal several important learning points including that DMS can occur with or without underlying organic disease. Active exploration of the nature of delusions in postpartum psychosis is required to mitigate the risk of harm to the infant and mother-infant bond. It may also uncover that these syndromes are more common in postpartum psychosis than previously realized. (shrink)

This chapter considers some epistemic aspects of interactions with those who are believed to be delusional. The chapter makes five main claims: first, for the day-to-day purposes of most individuals, it is helpful to understand delusions as extreme epistemic failures, failures that all are guilty of to some degree. Second, one should be cautious when attributing delusions to others because to call someone delusional can act to discredit them, and this can be especially dangerous when applied to members (...) of oppressed groups. Third, delusional individuals can indeed be wronged by epistemic injustice. Fourth, epistemic responsibility for delusions needs to be extended beyond the individual holding delusional beliefs to the conditions that shape those beliefs. Finally, the virtue of epistemic humility offers several important epistemic benefits in interactions with delusional others. (shrink)

Jennifer Radden has drawn attention to two features of delusion, ambivalence and subjectivity, which are problematic for theories of delusion that treat delusions as empirical beliefs. She argues for an ‘attitude’ theory of delusion. I argue that once the cognitive architecture of delusion formation is properly described the debate between doxastic and attitude theorists loses its edge. That architecture suggests that delusions are produced by activity in the ‘default mode network’ unsupervised by networks required for decontextualized processing. The cognitive properties (...) of these networks explain the features of delusion which generate the debate between doxastic and attitude theorists. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy, Psychiatry, & Psychology 11.1 (2004) 95-99 [Access article in PDF] Delusional Content and the Public Nature of Meaning:Reply to the Other Contributors Robert Klee The contribution by professors Bayne and Pacherie (2004) is an earnest attempt to defend a popular model of monothematic delusions against criticisms launched by John Campbell (2001). This model of monothematic delusions holds that such delusions are rational attempts by the sufferer to (...) explain to herself specific kinds of anomalous sensory/affective experiences. Bayne, Pacherie, Campbell, and for that matter Sass, Harper, and Georgaca, write as if semantic meaning accrued to words in a language term by term, as if meaning is "private" to the deluded person, and that she might therefore mean almost anything by her own idiosyncratic use of the public language she otherwise speaks. This is a notorious mistake. As Hilary Putnam famously put it in his classic 1975 paper "The meaning of 'meaning,'" "Cut the pie any way you like, 'meanings' just ain't in the head" (1975, 227). That is, meanings are not ethereal interior mental objects, private to the speaker—they are not private inner episodes that take place in some mental center stage of consciousness. The deluded person does not and cannot succeed in changing the meaning of a term in a public language like English merely by an individual act of imaginative will involving the making of a bizarre assertion—not even if she repeats it a thousand times. The public nature of meaning, if I can coin a phrase for it, is the central theme in the work of the later Wittgenstein. Even before Putnam, Wittgenstein had made the same point in his Philosophical Investigations via a famous footnote in which he writes, Can I say 'bububu' and mean "If it doesn't rain I shall go for a walk"?—it is only in a language that I can mean something by something. This shows clearly that the grammar of 'to mean' is not like that of the expression 'to imagine' and the like." (2001, 18e) Wittgenstein argues that the answer to the rhetorical question in the footnote is an emphatic No. To mean something by the use of words in a public language is not equivalent to an act of individual free imagination. The languages we each speak, including the unfortunately deluded among us, are public not private, and insofar as the notion of meaning has an understandable sense, the meaning of a term is fixed by its actual public use, across large time intervals, in many different contexts, by the many millions of speakers of the language in question. It is time that segments of the intellectual map beyond the borders [End Page 95] of philosophy got the news about this, for I think an appreciation of this point would forestall certain objections and argumentative moves that otherwise take up space in the psychological literature.Bayne and Pacherie (2004) describe Campbell's model of monothematic delusions as proposing that "delusions can be usefully regarded as Wittgensteinian framework propositions" (p. 7). I have discussed this notion in my main paper, although I do not use the terms framework propositions; I stick to Wittgenstein's own words. Wittgenstein called them, literally in the German, propositions that "stand fast for us" (feststehen). This description strikes me as less misleading than calling them framework propositions, for the latter expression suggests that they could in some sense be replaceable by a different framework of framework propositions, something that Wittgenstein in no way ever meant to suggest. Wittgenstein did not think of these propositions as individualized or privately owned—as beliefs that might vary considerably across the population of speakers of the language in which they are expressed. That is why he explicitly wrote that they stand fast for us. Note the plural pronoun. There is something irreducibly collective, something publicly owned, about the epistemology of these propositions. These propositions represent the accumulated certainties that precipitate out of what is commonly shared in human experience over long time intervals. Precisely because what stands fast for us is... (shrink)

BACKGROUND: Delusions in schizophrenia are commonly approached as empirical false beliefs about everyday reality. Phenomenological accounts, by contrast, have suggested that delusions are more adequately understood as pertaining to a different kind of reality experience. How this alteration of reality experience should be characterised, which dimensions of experiential life are involved, and whether delusional reality might differ from standard reality in various ways is unclear and little is known about how patients with delusions value and relate to these experiential (...) alterations. This study aimed to investigate the nature of delusional reality experience, and its subjective apprehension, in individuals with lived experience of delusions and a schizophrenia-spectrum diagnosis. METHODS: In this qualitative phenomenological study, we recruited individuals with lived experience of delusions and a schizophrenia-spectrum diagnosis from two psychiatric-hospital services in Belgium using homogenous sampling. Criteria for participation were having undergone at least one psychotic episode with occurring delusional symptoms, present at least 1 year before participation, on the basis of clinical notes assessed by the attending psychiatrist; a schizophrenia-spectrum diagnosis, ascertained through clinical interview by the attending psychiatrist upon admission; being aged between 18 years and 65 years; and having the capacity to give informed consent. Exclusion criteria included worries concerning capacity to consent and risk of distress caused by participation. We did phenomenologically driven semi-structured interviews with the participants to explore the nature of delusional reality experience and their subjective valuation of these experiences. We used interpretative phenomenological analysis, a qualitative method tailored to the in-depth exploration of participants’ first-person perspective, to analyse their accounts. FINDINGS: Between March 2, 2020, and Sept 30, 2020, 18 adults participated in the interview study. The findings suggest that delusions are often embedded in wide-ranging alterations of basic reality experience, involving quasi-ineffable atmospheric and ontological qualities that undermine participants’ sense of the world as unambiguously real, fully present, and shared with others. We also found that delusional reality experience can differ from standard reality in various ways, across multiple dimensions, and that participants are often implicitly or explicitly aware of the distinction between delusional and standard reality. Delusional experience can have an enduring value and meaning that is not fully captured by a strictly medical perspective. INTERPRETATION: Increased awareness and recognition of the distinctive nature of delusional reality experience, in both clinical and research settings, can improve diagnostic accuracy, explanatory models, and therapeutic support for individuals with delusions whose lived realities are not always evident from an everyday perspective. FUNDING: FWO Flanders. TRANSLATION: For the Dutch translation of the abstract see Supplementary Materials section. (shrink)

: The notion of a delusion occupies a central place in psychotherapy. The presence of delusional thinking in a patient is often regarded as indicative of psychosis. And yet, the nature of a delusion is still widely disputed. The difficulty of defining a delusion has proved so difficult that some prominent authors have declared the task impossible. The aim of this paper is to offer a characterisation of delusional systems of thought. In this paper is argued that delusions, (...) unlike scientific explanations and the explanations generally offered by common sense, fail to minimise that which requires explanation. In the first part of the paper, difficulties with extant accounts will be discussed. In the following parts, the author’s own account of delusional thoughts will be developed and some difficult cases considered. It will be argued that delusions differ from more typical beliefs in the number of things that they leave unexplained. Delusions, unlike those beliefs we typically see as rational, bring about an increase in the number of things requiring explanation. Keywords: Delusions; Epistemology; Analysis; Explanation; Rationality Aspetti epistemologici del pensiero delirante Riassunto: La nozione di delirio occupa una posizione centrale nell’ambito della psicoterapia. La presenza del pensiero delirante in un paziente è considerata spesso come un indice di psicosi. E, tuttavia, la natura del delirio non è ancora oggetto di ampio accordo tra gli studiosi. La difficoltà nel definire il delirio si è mostrata talmente ostica che diversi importanti studiosi hanno dichiarato questo compito impossibile. Lo scopo di questo lavoro è quello di offrire una caratterizzazione dei sistemi di pensiero delirante. Si sosterrà che i deliri, diversamente dalle spiegazioni scientifiche e da quelle offerte generalmente dal senso comune, non riescono a ridurre quanto necessita di una spiegazione. Nella prima parte del lavoro, saranno discusse le difficoltà degli approcci correnti. Nelle parti seguenti verrà proposto l’approccio dell’autore ai pensieri deliranti e verranno presi in esame alcuni casi complessi. Si sosterrà che i deliri si distinguono dai casi più tipici di credenza per il numero di cose che lasciano senza spiegazione. I deliri, diversamente dalle credenze che tipicamente consideriamo irrazionali, determinano un incremento del numero di cose che richiedono una spiegazione. Parole chiave: Delirio; Epistemologia; Analisi; Spiegazione; Razionalità. (shrink)

Delusional beliefs are typically pathological. Being pathological is clearly distinguished from being false or being irrational. Anna might falsely believe that his husband is having an affair but it might just be a simple mistake. Again, Sam might irrationally believe, without good evidence, that he is smarter than his colleagues, but it might just be a healthy self-deceptive belief. On the other hand, when a patient with brain damage caused by a car accident believes that his father was (...) replaced by an imposter or another patient with schizophrenia believes that “The Organization” painted the shops on a street in red and green to convey a message, these beliefs are not merely false or irrational. They are pathological. What makes delusions pathological? This paper explores the negative features because of which delusional beliefs are pathological. First, I critically examine the proposals according to which delusional beliefs are pathological because of (1) their strangeness, (2) their extreme irrationality, (3) their resistance to folk psychological explanations or (4) impaired responsibility-grounding capacities of people with them. I present some counterexamples as well as theoretical problems for these proposals. Then, I argue, following Wakefield’s harmful dysfunction analysis of disorder, that delusional beliefs are pathological because they involve some sorts of harmful malfunctions. In other words, they have a significant negative impact on wellbeing (=harmful) and, in addition, some psychological mechanisms, directly or indirectly related to them, fail to perform the jobs for which they were selected in the past (=malfunctioning). An objection to the proposal is that delusional beliefs might not involve any malfunctions. For example, they might be playing psychological defence functions properly. Another objection is that a harmful malfunction is not sufficient for something to be pathological. For example, false beliefs might involve some malfunctions according to teleosemantics, a popular naturalist account of mental content, but harmful false beliefs do not have to be pathological. I examine those objections in detail and show that they should be rejected after all. (shrink)

Background Delusions are a significant feature of mental illnesses and can occur in many clinical conditions (Maher, 2001) yet the standard clinical definition (American Psychiatric Association. DSM-5 Task Force, 2013) is highly contentious. Much of the literature holds elements such as bizarreness of content and incorrigibility of belief as defining factors of delusion. However, on closer inspection, delusions are not so easy to pin down. The difficulty in defining delusion is not a new one as “…we are all capable (...) of having convictions and it is a universal human characteristic to hold on to our own mistaken judgements.” (Jaspers, 1963, p.63). Objective I intend to highlight some of the difficulties associated with the definition of delusion and perhaps clarify the phenomenology. Methodology I examine some of the philosophical, psychological and psychiatric literature with regard to the definition of delusion. I also consider my experience of my own mental activity and experiences from my therapeutic work. Results/Conclusion I identify that delusions are a heterogeneous group and that there may be more than one ‘class’ of delusion. I also show that delusions are multi-dimensional with characteristics on a continuum with normal beliefs and that further research is needed to clarify the phenomenology. (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)

In this book, psychologists and philosophers describe and discuss a range of case studies of delusional beliefs, drawing out general lessons both for the cognitive architecture of the mind and for the notion of rationality, and exploring connections between the delusional beliefs that occur in schizophrenia and the flawed understanding of beliefs that is characteristic of autism.

Delusions are usually defined as false beliefs about the state of affairs in the public world. Taking this premise as unquestionable, the debate in cognitive science tends to oscillate between the so-called 'rationalist approach'- proposing some breakdown in the central intellective modules embodying human rationality - and the 'empiricist approach' - proposing a primary peripheral deficit , followed by explanatory efforts in the form of delusions. In this article the foundational assumption about delusion is questioned. Especially in the case of (...) schizophrenia, delusions are not epistemic statements about external world but metaphorical reports of altered structure of experiencing . Delusions as epistemic statements or beliefs occur paradigmatically in delusional disorder . These two types of delusions are compared from a primarily phenomenological stance. (shrink)

In this book, psychologists and philosophers describe and discuss a range of case studies of delusional beliefs, drawing out general lessons both for the cognitive architecture of the mind and for the notion of rationality, and exploring connections between the delusional beliefs that occur in schizophrenia and the flawed understanding of beliefs that is characteristic of autism.

This volume brings together recent work on the nature of belief, imagination, and delusion. Whilst philosophers of mind and epistemology employ notions of belief and imagination in their theorizing, parallel work seeking to make these notions more precise continues. Delusions are standardly taken to be bizarre beliefs occurring in the clinical population, which do not respond to evidence. The purpose of this collection of essays is to get clearer on the nature of belief and imagination, the ways (...) in which they relate to one another, and how they might be integrated into accounts of delusional belief formation. The jumping off point is the idea that recent work in philosophy of mind and epistemology which has sought to characterise the nature of belief and imagination allows us to formulate the issues with new precision, by, for example, drawing on work concerning how imagination is involved in delusion formation, or work concerning how to properly distinguish imagination from belief. The volume also considers questions concerning imagination's architecture, the role of metacognitive error in our mental lives, how best to understand delusional experience, and the relationship between delusion and evidence. The contributors are ideally placed to explore these issues, both individually and as a collective. With interests spanning different disciplines (philosophy, psychology, cognitive science), and approaches (theoretical, empirically informed), the result is a rich and varied collection of insights. (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)

A curious and comparatively neglected element of death penalty jurisprudence in America is my target in this paper. That element concerns the circumstances under which severely mentally disabled persons, incarcerated on death row, may have their sentences carried out. Those circumstances are expressed in a part of the law which turns out to be indefensible. This legal doctrine—competence-for-execution —holds that a condemned, death-row inmate may not be killed if, at the time of his scheduled execution, he lacks an awareness of (...) his impending death or the reasons for it. I argue that the law of CFE should be abandoned, along with the notion that it is permissible to kill the deeply disturbed just so long as they meet some narrow test of readiness to die. By adopting CFE, the courts have been forced to give independent conceptual and moral significance to a standard for competence that simply cannot bear the weight placed upon it. To be executable, CFE requires that a condemned prisoner meet a standard demonstrating an awareness of certain facts about his death. Yet this standard both leads to confusing and counter-intuitive results and is unsupported either by the reasons advanced by the courts on its behalf or by any of the standard theoretical justifications of criminal punishment. If executing the profoundly psychotic or delusional is wrong the law needs a better account of the wrong done when prisoners like Ford are killed. I suggest wherein that wrong might be located. (shrink)

After presenting and criticizing recent theoretical work on the nature of delusional belief, I argue that the works of the later Wittgenstein and Donald Davidson offer heretofore underappreciated insights into delusional belief. I distinguish two general kinds of delusion: pedestrian and stark. The former can be explained as cognitive mistakes of various kinds, whereas the latter I argue are necessarily inexplicable. This thesis requires the denial of the Davidsonian dogma that rationality is constitutive of mental content. (...) I claim that the dogma holds only for normal cognition and is violated precisely in the case of stark delusion. (shrink)

In their pursuit of adaptively biased misbelief-making systems, McKay & Dennett (M&D) describe a putative doxastic shear-pin system which enables misbeliefs to form in situations of extreme psychological stress. Rather than discussing their argument, I consider how this shear-pin system might combine with both pathological belief-making ( breakdowns caused by neuropathy) and normal belief-making to explain a spectrum of delusions.

Clinical delusions have traditionally been characterized as beliefs in psychiatry. However, philosophers have recently engaged with the empirical literature and produced a number of objections to the so-called doxastic status of delusion, stemming mainly from the mismatch between the functional role of delusions and that expected of beliefs. In response to this, an appeal to dispositionalism about the nature of belief has been proposed to vindicate the doxastic status of delusion. In this paper, I first present the objections to (...) attributing beliefs to delusional patients and the application of dispositionalism in the attempt to vindicate doxasticism. I then assess this application and some responses to the objections to the doxastic characterization. Finally, I offer some conclusions about the limits of folk-psychological concepts in the characterization and explanation of complex psychological phenomena such as delusions. (shrink)

People acquire new beliefs in various ways. One of the most important of these is that new beliefs are acquired as a response to experiencing events that one did not expect. This involves a form of inference distinct from both deductive and inductive inference: abductive inference. The concept of abduction is due to the American pragmatist philosopher C. S. Peirce. Davies and Coltheart elucidated what Peirce meant by abduction, and identified two problems in his otherwise promising account requiring solution if (...) that account were to become fully workable. Here we propose solutions to these problems and offer an explicit cognitive model of how people derive new beliefs from observations of unexpected events, based on Peirce's work and Sokolov's ideas about prediction error triggering new beliefs. We consider that this model casts light not only upon normal processes of belief formation but also upon the formation of delusional beliefs. (shrink)

Just as sadness is not always a symptom of mood disorder, irrational beliefs are not always symptoms of illness. Pathological irrational beliefs are distinguished from non-pathological ones by considering whether their existence is best explained by assuming some underlying dysfunctions. The features from which to infer the pathological nature of irrational beliefs are: un-understandability of their progression; uniqueness; coexistence with other psycho-physiological disturbances and/or concurrent decreased levels of functioning; bizarreness of content; preceding organic diseases known to be associated with irrational (...) beliefs; treatment response to medical intervention, etc. Severe irrationality is sometimes caused by normal human motivation rather than by mental or physical dysfunction. Pure forms of self-deception may satisfy the diagnostic criteria of delusional disorder, but there may be no evidence that suggests that they are caused by illness. Although those with pathological delusions do not recognize their delusions as symptomatic of illness, differentiating pathological beliefs from normal irrational beliefs is vitally important: If a belief is pathological, psychiatrists must seriously consider treating the patient against her will. If it is not pathological, conversely, involuntary treatments are prohibited because they offend her basic autonomy. (shrink)

People suffering from severe monothematic delusions, such as Capgras, Fregoli, or Cotard patients, regularly assert extraordinary and unlikely things. For example, some say that their loved ones have been replaced by impostors. A popular view in philosophy and cognitive science is that such monothematic delusions aren't beliefs because they don't guide behaviour and affect in the way that beliefs do. Or, if they are beliefs, they are somehow anomalous, atypical, or marginal beliefs. We present evidence from five studies that folk (...) psychology unambiguously views monothematic delusions as stereotypical beliefs. This calls into question widespread assumptions in the professional literature about belief's stereotypical functional profile. We also show that folk psychology views delusional patients as holding contradictory beliefs. And we show that frequent assertion is a powerful cue to belief ascription, more powerful than even a robust and consistent track record of non-verbal behaviour. (shrink)

The Australian philosopher Philip Gerrans ambitiously tries to provide a general theory about the formation of delusions that should enclose neuronal, cognitive and phenomenological levels of description. His theory is defined as narrative and it is grounded on the so called “default thoughts”, that consist in simulations, autobiographical narrative fragments produced by the Default Mode Network (DMN). The DMN is a powerful simulation system that evolved to allow humans to simulate and imagine experiences in the absence of an eliciting stimulus. (...) Such imaginative/simulative process is precariously disciplined by the Self’s demands of narrative coherence. The Author’s aim is to waive the notion of belief and the causal role played by the impairments of fixation-beliefs system in the onset of delusions, as predicted by the principle doxastic theories. (shrink)

This commentary challenges Rogers & McClelland (R&M) to use their model to account for delusional belief formation and maintenance. The gradual development of delusions and the nature of disconnectivity in Capgras delusions are used to illustrate the role of emotional salience in delusions. It is not clear how this kind of emotional saliency can be represented within the current architecture.