This thesis develops a novel framework for explaining delusions. In Chapter 1, I introduce the two fundamental challenges posed by delusions: the evidence challenge lies in explaining the flagrant ways delusions flout evidence; and the specificity challenge lies in explaining the fact that patients’ delusions are often about a few specific themes, and patients rarely have a wide range of delusional or odd beliefs. In Chapter 2, I discuss the strengths and weaknesses of current theories of delusions, which typically appeal (...) to one or both of two factors: anomalous experience and reasoning abnormality. I argue that anomalous experience can help explain the specificity of delusions, but has difficulties in addressing the evidence challenge; reasoning abnormality can help address the evidence challenge, but has difficulties in explaining the specificity of delusions. This suggests that there may be an important factor that has not been captured by current theories of delusions. To search for this missing factor, in Chapter 3, I turn to normal believing. Inspired by the literature on Cartesian clarity and phenomenal dogmatism, I develop a dual-force framework of believing, according to which beliefs can be understood as the results of the interaction between the justificatory force and causal force of evidence and the justificatory force and causal force of clear experience, in which something clearly seems to be so to the subject. This framework suggests that the missing factor may be the clear experience with its distinctive phenomenal clarity that compels assent. In Chapter 4, I return to delusions, and argue that the dualforce framework can help us to get a better grip on some personal descriptions of delusions; make progress in addressing the evidence and specificity challenges of delusions; and shed new light on the underpinnings of delusions. In the end, I conclude with some remaining questions for future study. (shrink)

Introspection has traditionally been defined as a privileged way of obtaining beliefs about one’s occurrent mental states, and the idea that it is psychologically and epistemically different from non-introspective belief formation processes has been widely defended. At the same time, philosophers and cognitive scientists alike have pointed out the unreliability of introspective reports in consciousness research. In this paper, I will argue that this dissonance in the literature can be explained by differentiating between infallible and informative introspective beliefs. I will (...) argue that the latter are formed similarly to beliefs about the external world, and are therefore susceptible to similar success and failure conditions. Understanding introspection as belief-like will help to locate possible sources of error in regular as well as in pathological cases, carrying relevant implications for the relationship between experience, belief, and delusion. (shrink)

Delusions are usually considered as harmful and dysfunctional beliefs, one of the primary symptoms of a psychiatric illness and the mark of madness in popular culture. However, in recent times a much more positive role has been advocated for delusions. More specifically, it has been argued that delusions might be an answer to a problem rather than problems in themselves. By delivering psychological and epistemic benefits, delusions would allow people who face severe biological or psychological difficulties to survive in their (...) environment - although this has obvious epistemic costs, as the delusion is fixed and irresponsive to compelling counterevidence. In other words, it has been argued that delusions are biologically adaptive. The adaptiveness of delusions has been compared by Ryan McKay and Daniel Dennett to a shear pin, a mechanism installed in the drive engine of some machines which is designed to shear whenever the machine is about to break down. By breaking, shear pins prevent the machine from collapsing and allow it to keep functioning, although in an impaired manner. Similarly, when delusions form, they would allow a cognitive or psychological system which is about to collapse to continue its functioning, although in an impaired manner. However, this optimistic picture of delusions risks being undermined by both theoretical and empirical considerations. Using Sarah Fineberg and Philip Corlett’s recent predictive coding account as a paradigmatic model of the biological adaptiveness of delusions, I develop two objections to it: principles of parsimony and simplicity suggest that maladaptive models of delusions have an upper hand over adaptive models; and the available empirical evidence suggests that at least some delusions stand good chances of being psychologically adaptive, but it is unlikely that they also qualify as biologically adaptive. (shrink)

In this paper, I will present and advocate a view about what we are doing when we attribute delusion, namely, say that someone is delusional. It is an “expressivist” view, roughly analogous to expressivism in meta-ethics. Just as meta-ethical expressivism accounts for certain key features of moral discourse, so does this expressivism account for certain key features of delusion attribution. And just as meta-ethical expressivism undermines factualism about moral properties, so does this expressivism, if correct, show that certain attempts to (...) objectively define delusion are misguided. I proceed as follows. I start by examining different attempts at defining delusion, separating broadly psychiatric attempts from epistemic ones. I then present a change of approach, according to which we question whether the term “delusion” is in the business of (merely) describing reality. I then support this proposal, first, by borrowing standard lines of argument from meta-ethics (including ontological reluctance, intrinsic motivation, and deep disagreement) but also, by inference to the best explanation of some the features we see when we try to theorise about delusion (namely that it is hard to define, and that our delusion attributions are elicited by a plurality of norms). (shrink)

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)

Corlett (2019) raises two groups of challenges against the two-factor theory of delusions: One focuses on weighing “the evidence for … the two-factor theory”; the other aims to question “the logic of the two-factor theory” (p. 166). McKay (2019) has robustly defended the two-factor theory against the first group. But the second group, which Corlett believes is in many aspects independent of the first group and Darby (2019, p. 180) takes as “[t]he most important challenge to the two-factor theory raised (...) by Dr. Corlett”, has by large remained. Here I offer my two cents in response to the second group. More specifically, I argue that Corlett’s challenges to the logic of the two-factor theory, concerning modularity, double dissociation and cognitive penetration, seem to be based on some misunderstandings of the two-factor theory. (shrink)

In folie à deux, a ‘primary’ patient transmits a delusional belief to one or more ‘secondary’ patients who then adopt and share the belief. This paper applies the two‐factor theory of delusion to retrospectively analyse published cases of folie à deux. Lessons from this retrospective analysis include, firstly, that two‐factor theorists need to shift their focus from endogenous processes to consider the exogenous source of delusional content in most secondaries. Secondly, secondaries who come to share the belief via normal processes (...) of social contagion only qualify as delusional by virtue of the abnormal persistence of their belief, albeit a temporary persistence in those secondaries who abandon their belief soon after separation from the primary. Underpinning this abnormal persistence may be a form of inhibitory failure—a difficulty with inhibiting a belief to allow reasoning for and against it being true. (shrink)

Psychopathological delusions have a number of features that are curiously difficult to explain. Delusions are resistant to counterevidence and impervious to counterargument. Delusions are theoretically, affectively, and behaviorally circumscribed: delusional individuals often do not act on their delusions and often do not update beliefs on the basis of their delusions. Delusional individuals are occasionally able to distinguish their delusions from other beliefs, sometimes speaking of their “delusional reality.” To explain these features, I offer a model according to which, contrary to (...) appearances, delusions are not beliefs at all. Delusions are acceptances that are generated by pathologically powerful cognitive feelings. This model has implications for the way that we should think about non-pathological doxastic states and emotions. (shrink)

This paper examines Todd Feinberg's theory of the misidentification syndromes.

The patient with Capgras’ syndrome claims that people very familiar to him have been replaced by impostors. I argue that this disorder is due to the destruction of a representation that the patient has of the mind of the familiar person. This creates the appearance of a familiar body and face, but without the familiar personality, beliefs, and thoughts. The posterior site of damage in Capgras’ is often reported to be the temporoparietal junction, an area that has a role in (...) the mindreading system, a connected system of cortical areas that allow us to attribute mental states to others. Just as the Capgras’ patient claims that that man is not his father, the patient with asomatognosia claims that his arm is not really his. A similar account applies here, in that a nearby brain area, the supramarginal gyrus, is damaged. This area works in concert with the temporoparietal junction and other areas to produce a large representation of a mind inside a body situated in an environment. Damage to the mind-representing part of this system (coupled with damage to executive processes in the prefrontal lobes) causes Capgras’ syndrome, whereas damage to the body-representing part of this system (also coupled with executive damage) causes asomatognosia. (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.

The imperviousness of delusions to counter-evidence makes it tempting to classify them as imaginings. Bayne and Pacherie argue that adopting a dispositional account of belief can secure the doxastic status of delusions. But dispositionalism can only secure genuinely doxastic status for mental states by giving folk-psychological norms a significant role in the individuation of attitudes. When such norms individuate belief, deluded subjects will not count as believing their delusions. In general, dispositionalism won't confer genuinely doxastic status more often than do (...) competing accounts of belief. (shrink)

Clinical delusions are difficult to investigate in the laboratory because they co-occur with other symptoms and with intellectual impairment. Partly for these reasons, researchers have recently begun to use hypnosis with neurologically intact people in order to model clinical delusions. In this paper we describe striking analogies between the behavior of patients with a clinical delusion of mirrored self misidentification, and the behavior of highly hypnotizable subjects who receive a hypnotic suggestion to see a stranger when they look in the (...) mirror. Based on these analogies, we argue that the use of hypnosis is a reliable method to investigate the surface features of clinical delusions. But to what extent can hypnosis successfully recreate delusions? Can it also contribute to a better understanding of delusion formation? Although clinical delusions and hypnotically induced beliefs are different in etiology, some analogies can be identified in the underlying processes that characterise them, based on the two-factor theory of delusion formation. (shrink)

When laws or legal principles mention mental states such as intentions to form a contract, knowledge of risk, or purposely causing a death, what parts of the brain are they speaking about? We argue here that these principles are tacitly directed at our prefrontal executive processes. Our current best theories of consciousness portray it as a workspace in which executive processes operate, but what is important to the law is what is done with the workspace content rather than the content (...) itself. This makes executive processes more important to the law than consciousness, since they are responsible for channeling conscious decision-making into intentions and actions, or inhibiting action.We provide a summary of the current state of our knowledge about executive processes, which consists primarily of information about which portions of the prefrontal lobes perform which executive processes. Then we describe several examples in which legal principles can be understood as tacitly singling out executive processes, including principles regarding defendants’ intentions or plans to commit crimes and their awareness that certain facts are the case, as well as excusatory principles which result in lesser responsibility for those who are juveniles, mentally ill, sleepwalking, hypnotized, or who suffer from psychopathy. (shrink)

The impact of our desires and preferences upon our ordinary, everyday beliefs is well-documented [Gilovich, T. . How we know what isn’t so: The fallibility of human reason in everyday life. New York: The Free Press.]. The influence of such motivational factors on delusions, which are instances of pathological misbelief, has tended however to be neglected by certain prevailing models of delusion formation and maintenance. This paper explores a distinction between two general classes of theoretical explanation for delusions; the motivational (...) and the deficit. Motivational approaches view delusions as extreme instances of self-deception; as defensive attempts to relieve pain and distress. Deficit approaches, in contrast, view delusions as the consequence of defects in the normal functioning of belief mechanisms, underpinned by neuroanatomical or neurophysiological abnormalities. It is argued that although there are good reasons to be sceptical of motivational theories , recent experiments confirm that motives are important causal forces where delusions are concerned. It is therefore concluded that the most comprehensive account of delusions will involve a theoretical unification of both motivational and deficit approaches. (shrink)

Young and colleagues . Betwixt life and death: case studies of the Cotard delusion. In P. W. Halligan & J. C. Marshall , Method in madness: Case studies in cognitive neuropsychiatry. Mahway, NJ: Lawrence Erlbaum Associates.) have suggested that cases of the Cotard delusion result when a particular perceptual anomaly occurs in the context of an internalising attributional style. This hypothesis has not previously been tested directly. We report here an investigation of attributional style in a 24-year-old woman with Cotard (...) delusion . LU’s attributional style was assessed using the Internal, Personal and Situational Attributions Questionnaire . A new measure of causal locus: the internal, personal and situational attributions questionnaire. Personality and Individual Differences, 20, 261–264.). LU showed a significantly greater proportion of internalising attributions than the control group, both overall and for negative events specifically. The results obtained thus support an association of Cotard delusion with an internalising attributional style, and are therefore consistent with the account of Young and colleagues. The potential brain basis of Cotard delusion is discussed. (shrink)

We show how an epistemology informed by cognitive science promises to shed light on an ancient problem in the philosophy of mathematics: the problem of exactness. The problem of exactness arises because geometrical knowledge is thought to concern perfect geometrical forms, whereas the embodiment of such forms in the natural world may be imperfect. There thus arises an apparent mismatch between mathematical concepts and physical reality. We propose that the problem can be solved by emphasizing the ways in which the (...) brain can transform and organize its perceptual intake. It is not necessary for a geometrical form to be perfectly instantiated in order for perception of such a form to be the basis of a geometrical concept. (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)

In this paper we defend the doxastic conception of delusions against the metacognitive account developed by Greg Currie and collaborators. According to the metacognitive model, delusions are imaginings that are misidentified by their subjects as beliefs: the Capgras patient, for instance, does not believe that his wife has been replaced by a robot, instead, he merely imagines that she has, and mistakes this imagining for a belief. We argue that the metacognitive account is untenable, and that the traditional conception of (...) delusions as beliefs should be retained. (shrink)

I argue that some cases of delusions show the inadequacy of those theories of interpretation that rely on a necessary rationality constraint on belief ascription. In particular I challenge the view that irrational beliefs can be ascribed only against a general background of rationality. Subjects affected by delusions seem to be genuine believers and their behaviour can be successfully explained in intentional terms, but they do not meet those criteria that according to Davidson (1985a) need to be met for the (...) background of rationality to be in place. (shrink)

Anosognosia is literally ‘unawareness of or failure to acknowledge one’s hemi- plegia or other disability’ (OED). Etymology would suggest the meaning ‘lack of knowledge of disease’ so that anosognosia would include any denial of impairment, such as denial of blindness (Anton’s syndrome). But Babinski, who introduced the term in 1914, applied it only to patients with hemiplegia who fail to acknowledge their paralysis. Most commonly, this is failure to acknowledge paralysis of the left side of the body following damage to (...) the right hemisphere of the brain. In this paper, we shall mainly be concerned with anosognosia for hemiplegia. But we shall also use the term ‘anosognosia’ in an inclusive way to encompass lack of knowledge or acknowledgement of any impairment. Indeed, in the construction ‘anosognosia for X’, X might even be anosognosia for some Y. (shrink)

The aim of this article is to analyze those theories that interpret misidentification delusions in terms of mentalization. The hypothesis under examination holds that a mentalization framework is useful for describing misidentification delusions when identification is thought to be partially based on mentalization. The article provides both a characterization and possible interpretations of such delusions, and possible relations between misidentification and mentalization are scrutinized. Whether the mentalization approach may explain or describe such kinds of mental disorders is considered, with the (...) conclusion that while this approach is unsatisfactory, there is some room for future improvement. (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 present paper investigated the nature and structure of extra-terrestrial beliefs. Respondents completed a booklet containing items measuring belief in extra-terrestrial life, alien visitation, and paranormal belief (Revised Paranormal Belief Scale, R-PBS; and the Australian Sheep Goat Scale, ASGS). Responses were analyzed using principal component analysis (PCA), and a three-factor structure emerged: alien visitation, belief in extra-terrestrial life, and the search for extra-terrestrials. Further analysis revealed that males scored higher than females on belief in extra-terrestrial life and the search for (...) extra-terrestrial life. No difference was observed for alien visitation. Correlational analysis found significant positive associations between each of the extra-terrestrial life factors and alien visitation. In addition to this, the extra-terrestrial life factors and alien visitation were found to correlate with overall paranormal belief (ASGS), and the two factors of the R-PBS (Traditional Paranormal Belief and New Age Philosophy). Alien Visitation was more strongly correlated with the paranormal belief measures than the extra-terrestrial belief factors; these were found to be negatively correlated with the paranormal belief measures when Alien Visitation was controlled for. These findings indicate that only more extreme Alien Visitation beliefs were associated with belief in the paranormal. Keywords: alien visitation—belief in extra-terrestrial life—search for extra-terrestrial life—paranormal belief. (shrink)

Fregoli delusion is the mistaken belief that some person currently present in the deluded person's environment is a familiar person in disguise. The stranger is believed to be psychologically identical to this known person even though the deluded person perceives the physical appearance of the stranger as being different from the known person's typical appearance. To gain a deeper understanding of this contradictory error in the normal system for tracking and identifying known persons, we conducted a detailed survey of all (...) the Fregoli cases reported in the literature since the seminal Courbon and Fail paper. Our preliminary reading of these cases revealed a notable lack of definitional clarity. So, we first formulated a classification scheme of different person misidentification delusions so as to identify those cases that qualified as instances of Fregoli according to the above characterization: the mistaken belief that a known person is present in the environment in a different guise to his or her typical appearance. We identified 38 clear cases of this type and set out to answer a series of questions motivated by current hypotheses about the origin of the Fregoli delusion. We asked whether the patients misidentified particular strangers, made reference to the misidentified known persons using wigs or plastic surgery , misidentified many different strangers or only one, showed other symptoms , and made inferences about the motives of the known persons in disguise. We conclude by discussing the implications of our findings for current hypotheses concerning the origin of the Fregoli delusion. (shrink)

Current models of delusion converge in proposing that delusional beliefs are based on unusual experiences of various kinds. For example, it is argued that the Capgras delusion (the belief that a known person has been replaced by an impostor) is triggered by an abnormal affective experience in response to seeing a known person; loss of the affective response to a familiar person’s face may lead to the belief that the person has been replaced by an impostor (Ellis & Young, 1990). (...) Similarly, the Cotard delusion (which involves the belief that one is dead or unreal in some way) may stem from a general.. (shrink)

Monothematic delusions are bizarre beliefs which are often accompanied by highly anomalous experiences. For philosophers and psychologists attracted to the exploration of mental phenomena in an evolutionary framework, these beliefs represent—notwithstanding their rarity—a puzzle. A natural idea concerning the biology of belief is that our beliefs, in concert with relevant desires, help us to navigate our environments, and so, in broad terms, an evolutionary story of human belief formation will likely insist on a function of truth (true beliefs tend to (...) lead to successful action). Monothematic delusions are systematically false and often harmful to the proper functioning of the agent and the navigation of their environment. So what are we to say? A compelling thought is that delusions are _malfunctioning_ beliefs. Compelling though it may be, I argue against this view on the grounds that it does not pay due attention to the circumstances in which monothematic delusions are formed, and fails to establish _doxastic_ malfunction. I argue instead that monothematic delusions are _misfunctioning_ beliefs, that is, the result of mechanisms of belief formation operating in historically abnormal conditions. Monothematic delusions may take their place alongside a host of other strange beliefs formed in difficult epistemic conditions, but for which no underlying doxastic malfunction is in play. (shrink)

The present study assessed the degree to which probabilistic reasoning performance and thinking style influenced perception of risk and self-reported levels of terrorism-related behaviour change. A sample of 263 respondents, recruited via convenience sampling, completed a series of measures comprising probabilistic reasoning tasks (perception of randomness, base rate, probability, and conjunction fallacy), the Reality Testing subscale of the Inventory of Personality Organization (IPO-RT), the Domain-Specific Risk-Taking Scale, and a terrorism-related behaviour change scale. Structural equation modelling examined three progressive models. Firstly, (...) the Independence Model assumed that probabilistic reasoning, perception of risk and reality testing independently predicted terrorism-related behaviour change. Secondly, the Mediation Model supposed that probabilistic reasoning and reality testing correlated, and indirectly predicted terrorism-related behaviour change through perception of risk. Lastly, the Dual-Influence Model proposed that probabilistic reasoning indirectly predicted terrorism-related behaviour change via perception of risk, independent of reality testing. Results indicated that performance on probabilistic reasoning tasks most strongly predicted perception of risk, and preference for an intuitive thinking style (measured by the IPO-RT) best explained terrorism-related behaviour change. The combination of perception of risk with probabilistic reasoning ability in the Dual-Influence Model enhanced the predictive power of the analytical-rational route, with conjunction fallacy having a significant indirect effect on terrorism-related behaviour change via perception of risk. The Dual-Influence Model possessed superior fit and reported similar predictive relations between intuitive-experiential and analytical-rational routes and terrorism-related behaviour change. The discussion critically examines these findings in relation to dual-processing frameworks. This includes considering the limitations of current operationalisations and recommendations for future research that align outcomes and subsequent work more closely to specific dual-process models. (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)

Hysteria has been the subject of controversy for many years, with theorists arguing about whether it is best explained by a hidden organic cause or by malingering and deception. However, it has been shown that hysterical paralysis cannot be explained in any of these terms. With the recent development of cognitive psychiatry, one may understand psychiatric and organic delusions within the same conceptual framework. Here I contrast hysterical conversion with anosognosia. They are indeed remarkably similar, though the content of their (...) respective delusions is the opposite. In hysterical paralysis, patients are not aware of their preserved ability, whereas in anosognosia for hemiplegia, patients are not aware of their disability. Four main explanations have been provided to account for anosognosia: metacognitive, attentional, motor, and motivational views. I will apply each of these accounts to hysterical paralysis and show that, at each level, hysterical conversion is the reverse of anosognosia. I will suggest that hysterical paralysis results from the interaction between attentional somatosensory amplification and affective inhibition of action. (shrink)

From an evolutionary standpoint, a default presumption is that true beliefs are adaptive and misbeliefs maladaptive. But if humans are biologically engineered to appraise the world accurately and to form true beliefs, how are we to explain the routine exceptions to this rule? How can we account for mistaken beliefs, bizarre delusions, and instances of self-deception? We explore this question in some detail. We begin by articulating a distinction between two general types of misbelief: those resulting from a breakdown in (...) the normal functioning of the belief formation system (e.g., delusions) and those arising in the normal course of that system's operations (e.g., beliefs based on incomplete or inaccurate information). The former are instances of biological dysfunction or pathology, reflecting “culpable” limitations of evolutionary design. Although the latter category includes undesirable (but tolerable) by-products of “forgivably” limited design, our quarry is a contentious subclass of this category: misbeliefs best conceived as design features. Such misbeliefs, unlike occasional lucky falsehoods, would have been systematically adaptive in the evolutionary past. Such misbeliefs, furthermore, would not be reducible to judicious – but doxastically1noncommittal – action policies. Finally, such misbeliefs would have been adaptive in themselves, constituting more than mere by-products of adaptively biased misbelief-producing systems. We explore a range of potential candidates for evolved misbelief, and conclude that, of those surveyed, onlypositive illusionsmeet our criteria. (shrink)

Naive physics beliefs can be systematically mistaken. They provide a useful test-bed because they are common, and also because their existence must rely on some adaptive advantage, within a given context. In the second part of the commentary we also ask questions about when a whole family of misbeliefs should be considered together as a single phenomenon.

This thesis is set out as a collection of self-standing essays. Throughout these essays, I try to illuminate a number of controversies surrounding the way in which delusions are formed, and relatedly, their nature and epistemic standing. In Chapter 2, after an introductory chapter, I flesh out a new ‘endorsement’ approach to the Capgras delusion, the main idea being that the delusion is formed by endorsing the content of a metaphorical-perceptual state in which a loved one is represented metaphorically as (...) an imposter. In Chapter 3, I take issue with the idea, prevalent in the literature, that Bayesian accounts of inference in delusions are best characterised as versions of ‘explanationism’. Taking one such influential account as a test case, I argue that it is no more or less compatible with the endorsement alternative, which says delusions are acquired non-inferentially from experience. In Chapter 4, I examine a recent critique of predictive processing theories of delusions, according to which such theories suffer two limitations: they fail to explain why an agent believes something delusional as opposed to nothing at all or something else; they fail to explain how delusional hypotheses are generated in the first place. I suggest ways in which these concerns might be addressed. In Chapter 5, I consider how the Spinozan theory of belief fixation can improve the prospects of doxasticism about delusions. Doxasticism has been criticised on the grounds that delusions typically do not abide by rational standards which we expect beliefs to conform to. If belief fixation is Spinozan, I argue, these deviations from rationality are not just compatible with, but supportive of, their status as beliefs. In Chapter 6, I ask whether misidentification delusions formed via endorsement processes have any measure of perceptual justification. To give the best chance of getting a ‘yes’ answer, I address the question from the perspective of perceptual dogmatism, as this appears the best option if we are to grant at least defeasible justifiedness to MDs. I argue that, even so, MDs are completely unjustified. (shrink)

On one influential view, the problems that should attract medical attention involve a disorder, because the goals of medical practice are to prevent and treat disorders. Based on this view, if there are no mental disorders then the status of psychiatry as a medical field is challenged. In this paper, I observe that it is often difficult to establish whether the problems that attract medical attention involve a disorder, and argue that none of the notions of disorder proposed so far (...) offers a successful demarcation criterion between medical and non-medical problems. As an illustration, I consider why delusions are considered pathological and whether they attract medical attention in virtue of being pathological, where ‘pathological’ stands for ‘being caused by a disorder’. Although there are several promising answers to what makes delusions pathological, available accounts of the pathological nature of delusions fail to distinguish delusions from other irrational beliefs that are not typically thought of as pathological; and cannot explain why delusions typically attract medical attention whereas other irrational beliefs do not. (shrink)

Elisabeth Pacherie is a research fellow in philosophy at Institut Jean Nicod, Paris. Her main research and publications are in the areas of philosophy of mind, psychopathology and action theory. Her publications include a book on intentionality (_Naturaliser_ _l'intentionnalité_, Paris, PUF, 1993) and she is currently preparing a book on action and agency.

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)

This paper assessed whether belief in conspiracy theories was associated with a particularly cognitive style (worldview). The sample comprised 223 volunteers recruited via convenience sampling and included undergraduates, postgraduates, university employees and alumni. Respondents completed measures assessing a range of cognitive-perceptual factors (schizotypy, delusional ideation and hallucination proneness) and conspiratorial beliefs (general attitudes towards conspiracist thinking and endorsement of individual conspiracies). Positive symptoms of schizotypy, particularly the cognitive-perceptual factor, correlated positively with conspiracist beliefs. The best predictor of belief in conspiracies (...) was delusional ideation. Consistent with the notion of a coherent conspiratorial mindset, scores across conspiracy measures correlated strongly. Whilst findings supported the view that belief in conspiracies, within the sub-clinical population, was associated with a delusional thinking style, cognitive-perceptual factors in combination accounted for only 32% of the variance. (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)

How do I know that I am the person who is moving? According to Wittgenstein (1958), the sense of agency involves a primitive notion of the self used as subject, which does not rely on any prior perceptual identification and which is immune to error through misidentification. However, the neuroscience of action and the neuropsychology of schizophrenia show the existence of specific cognitive processes underlying the sense of agency—the ‘‘Who'' system (Georgieff & Jeannerod, 1998) which is disrupted in delusions of (...) control (Frith, 1992). Yet, we have to be careful in the interpretation of such clinical symptoms, which cannot be so easily reduced to deficit of action monitoring or to lack of action awareness. Moreover, we should refine the definition of the sense of agency by distinguishing the sense of initiation and the sense of one's own movements. A conceptual analysis of the empirical data will lead us to establish the taxonomy of the different levels of action representations. (shrink)

Despite the diagnostic relevance of thought insertion for disorders such as schizophrenia, the debates about its aetiology are far from resolved. This paper claims that in paying exclusive attention to the perceptual and cognitive impairments leading to delusional experiences in general, current deficit approaches overlook the role that affective disturbances might play in giving rise to cases of thought insertion. In the context of psychosis, affective impairments are often characterized as a consequence of the stress and anxiety caused by delusional (...) episodes. However, here I explore some of the conceptual and empirical reasons to think that affective problems might in fact play a crucial doxastic role in the aetiology of thought insertion. Finally, I conclude by proposing a way of integrating the main insights of my analysis with the current ‘two-factor’ deficit approach to thought insertion and I explore the potential adaptive role that some delusions might have within this framework. (shrink)

Delusions are studied in two philosophical traditions: the continental or phenomenological tradition and the Anglo-American or analytic tradition. Each has its own view of delusions. Broadly stated, phenomenologists view delusions as a disturbed experience whilst most analytic researchers view them as beliefs. It is my contention that the most plausible account of delusions must ultimately incorporate valuable insights from both traditions. To illustrate the potential value of integration I provide a novel model of the Capgras delusion which describes how an (...) analytic, cognitive neuropsychological two-factor account of the Capgras delusion and the phenomenological view of delusions might be integrated. (shrink)

There are two main pathways to investigate the sense of body ownership, (i) through the study of the conditions of embodiment for an object to be experienced as one's own and (ii) through the analysis of the deficits in patients who experience a body part as alien. Here, I propose that E is embodied if some properties of E are processed in the same way as the properties of one's body. However, one must distinguish among different types of embodiment, and (...) only self-specific embodiment can lead to feelings of ownership. I address issues such as the functional role and the dynamics of embodiment, degrees and measures of ownership, and shared body representations between self and others. I then analyse the interaction between ownership and disownership. On the one hand, I show that there is no evidence that in the Rubber Hand Illusion, the rubber hand replaces the biological hand. On the other hand, I argue that the sense of disownership experienced by patients towards their body part cannot be reduced to the mere lack of ownership. (shrink)

Contemporary experimental research has emphasised the role of centrally generated signals arising from premotor areas in voluntary muscular force perception. It is therefore generally accepted that judgements of force are based on a central sense, known as the sense of effort, rather than on a sense of intra-muscular tension. Interestingly, the concept of effort is also present in the classical philosophy: to the French philosopher Maine de Biran [Maine de Biran . Mémoire sur la décomposition de la pensée , Vrin, (...) Paris ], the sense of effort is the fundamental component of self-experience, the landmark of the exercise of the will. In the present review, after a presentation of the nature and neurophysiological bases of effort sensation, we will examine its possible involvement in the neurocognitive process of agency. We will further focus on delusions of alien control in schizophrenic patients. Experimental data suggest that these patients have an abnormal awareness of effort caused by cerebral anomalies in the frontal and parietal lobes. (shrink)

In this paper I discuss the role played by disturbed phenomenology in accounting for the formation and maintenance of the Capgras delusion. Whilst endorsing a two-stage model to explain the condition, I nevertheless argue that traditional accounts prioritise the role played by some form of second-stage cognitive disruption at the expense of the significant contribution made by the patient’s disturbed phenomenology, which is often reduced to such uninformative descriptions as “anomalous” or “strange”. By advocating an interactionist model, I argue that (...) the delusional belief constitutes an attempt on the part of the patient to explain his/her initially odd and somewhat disturbed phenomenal content and, moreover, that the delusion then structures the patient’s experience such that what he/she perceives is an impostor. This fact is used to explain the delusional belief’s maintenance and resistance to revision. Thus, whilst accepting that second-stage cognitive disruption has a part to play in explaining the Capgras delusion, the emphasis here is placed on the role played by the patient’s changing phenomenal content and its congruence with the delusional belief. Unlike traditional two-stage models, which posit a unidirectional progression from experience to belief, the interactionist model advocates a two-way interaction between bottom-up and top-down processes. The application of this model to other delusional beliefs is also considered. (shrink)