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)

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)

There is evidence indicating that the Capgras delusion is grounded in some kind of anomalous experience. According to the endorsement model, the content of the delusion is already encoded in the Capgras subject's experience, and the delusion is formed simply by endorsing that content as veridical. Elisabeth Pacherie and Sam Wilkinson have in different ways attempted to articulate a comprehensive defence of this strategy, but here I argue that the endorsement model cannot be defended along the lines envisioned by either (...) of them. I then offer a more promising way of spelling out the model, according to which the anomalous experience implicated in Capgras is metaphorical in character. (shrink)

In his classic paper, “Delusional thinking and perceptual disorder,” Brendan Maher (1974) argues that psychiatric delusions are hypotheses designed to explain anomalous experiences, and are “developed through the operation of normal cognitive processes.” Consider, for instance, the Capgras delusion. Patients suffering from this particular delusion believe that someone close to them—such as a spouse, a sibling, a parent, or a child—has been replaced by an impostor: by someone who bears a striking resemblance to the “original” and who (for reasons unknown) (...) is intent on passing herself off as that individual. On Maher's view, the “Impostor Hypothesis” is the response of a rational agent to the anomalous experience it is invoked to explain. Recently, a number of philosophers have argued that Maher's analysis of delusion doesn't work when applied to the Capgras delusion. In this paper, I defend Maher's analysis against these arguments. However, my aim is not merely to defend Maher's analysis, but also to draw attention to some of the methodological problems that have led to its hasty dismissal. (shrink)

This paper draws on studies of the Capgras delusion in order to illuminate the phenomenological role of affect in interpersonal recognition. People with this delusion maintain that familiars, such as spouses, have been replaced by impostors. It is generally agreed that the delusion involves an anomalous experience, arising due to loss of affect. However, quite what this experience consists of remains unclear. I argue that recent accounts of the Capgras delusion incorporate an impoverished conception of experience, which fails to accommodate (...) the role played by ‘affective relatedness’ in constituting (a) a sense of who a particular person is and (b) a sense of others as people rather than impersonal objects. I draw on the phenomenological concept of horizon to offer an interpretation of the Capgras experience that shows how the content ‘this entity is not my spouse but an impostor’ can be part of the experience, rather than something that is inferred from a strange experience. (shrink)

Explanations of Capgras delusion and prosopagnosia typically incorporate a dual-route approach to facial recognition in which a deficit in overt or covert processing in one condition is mirror-reversed in the other. Despite this double dissociation, experiences of either patient-group are often reported in the same way – as lacking a sense of familiarity toward familiar faces. In this paper, deficits in the facial processing of these patients are compared to other facial recognition pathologies, and their experiential characteristics mapped onto the (...) dual-route model in order to provide a less ambiguous link between facial processing and experiential content. The paper concludes that the experiential states of Capgras delusion, prosopagnosia, and related facial pathologies are quite distinct, and that this descriptive distinctiveness finds explanatory equivalence at the level of anatomical and functional disruption within the face recognition system. The role of skin conductance response as a measure of ‘familiarity’ is also clarified. (shrink)

This paper explores early Australasian philosophy in some detail. Two approaches have dominated Western philosophy in Australia: idealism and materialism. Idealism was prevalent between the 1880s and the 1930s, but dissipated thereafter. Idealism in Australia often reflected Kantian themes, but it also reflected the revival of interest in Hegel through the work of ‘absolute idealists’ such as T. H. Green, F. H. Bradley, and Henry Jones. A number of the early New Zealand philosophers were also educated in the idealist tradition (...) and were influential in their communities, but produced relatively little. In Australia, materialism gained prominence through the work of John Anderson, who arrived in Australia in 1927, and continues to be influential. John Anderson had been a student of Henry Jones, who might therefore be said to have influenced both main strands of Australian philosophical thought. (shrink)

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)

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)

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)