Online research in philosophy

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.

Although well-documented, delusions have proved extremely hard to explain, and many important questions remain open, including the basic one of what kind of mental state a delusion is. The standard position is that delusions are beliefs (the doxastic conception); but there are difficulties for this view, and alternative characterizations have been offered. In this chapter I shall propose a new framework for conceptualizing delusions, building on recent work in philosophy of psychology and cognitive science. There are good reasons for thinking that the term ‘belief’ is commonly used to refer to two different types of mental state, located at different levels. This view harmonizes with work in the psychology of reasoning, where many researchers now endorse some form of dual system theory. I shall outline what is, I believe, the most attractive version of this two-level view and show how it offers an account of delusions that explains our competing intuitions about their status. The chapter is in four sections. The first introduces the doxastic conception and its problems. The second distinguishes the two levels of belief, and argues that delusions, if they are beliefs at all, belong to the second. The third section offers an account of second-level belief, according to which it is a species of a broader mental type, acceptance, which is dependent on attitudes at the first level. The fourth section proposes that delusions are acceptances, some of which fall within, and some without, the narrower class of secondlevel beliefs, and the chapter concludes with some reflections on the implications of this view. Throughout, I shall focus on monothematic delusions, rather than the elaborate polythematic kind, and use simple, schematic examples. This is not because I think it is unimportant to pay attention to the diversity of delusions and the detail of clinical observation (far from it). Rather, it reflects the modest aim of the chapter, which is to propose a hypothesis for subsequent elaboration and evaluation..

Are delusions best understood as a species of belief? Can I be deluded that p without believing that p? Because delusion is a clinical symptom, there are conflicting data at every turn. Perhaps it is best to think of delusions as beliefs not because they necessarily are beliefs, but because doing so helps patients. If one thinks that “denying that delusions are beliefs” means denying deluded patients “a voice in their own treatment” and that this would cut them off from alternative and healthier ways of thinking of themselves or the world, then one may wish to classify delusions as beliefs (see Kinderman and Bentall 2007, 288). I do not wish to classify delusions as beliefs (and I doubt ..

In this paper, I articulate the thesis that most delusional beliefs are continuous with other irrational beliefs. Any interpreter with some knowledge about the cognitive and affective life of subjects with delusions can at least partially understand their reports, and explain and predict their behavior in intentional terms. I identify similarities and differences between this approach to the nature of delusions and the approach adopted by Rhodes and Gipps, who have recently defended the view that people with delusions do not share the same bedrock beliefs as people without (the Background Theory of Delusions).

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..

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.

Delusions are explanations of anomalous experiences. A theory of delusion requires an explanation of both the anomalous experience _and _the apparently irrational explanation generated by the delusional subject. Hence, we require a model of rational belief formation against which the belief formation of delusional subjects can be evaluated. _Method. _I first describe such a model, distinguishing procedural from pragmatic rationality. Procedural rationality is the use of rules or procedures, deductive or inductive, that produce an inferentially coherent set of propositions. Pragmatic rationality is the use of procedural rationality _in context_. I then apply the distinction to the explanation of the Capgras and the Cotard delusions. I then argue that delusions are failures of pragmatic rationality. I examine the nature of these failures employing the distinction between performance and competence familiar from Chomskian linguistics. _Results. _This approach to the irrationality of delusions reconciles accounts in which the explanation of the anomalous experience exhausts the explanation of delusion, accounts that appeal to further deficits within the reasoning processes of delusional subjects, and accounts that argue that delusions are not beliefs at all. (Respectively, one-stage, two-stage, and expressive accounts.) _Conclusion. _In paradigm cases that concern cognitive neuropsychiatry the irrationality of delusional subjects should be thought of as a performance deficit in pragmatic rationality.

Delusions are a common symptom of schizophrenia and dementia. Though most English dictionaries define a delusion as a false opinion or belief, there is currently a lively debate about whether delusions are really beliefs and indeed, whether they are even irrational. The book is an interdisciplinary exploration of the nature of delusions. It brings together the psychological literature on the aetiology and the behavioural manifestations of delusions, and the philosophical literature on belief ascription and rationality. The thesis of the book is that delusions are continuous with ordinary beliefs, a thesis that could have important theoretical and practical implications for psychiatric classification and the clinical treatment of subjects with delusions. By bringing together recent work in philosophy of mind, cognitive psychology and psychiatry, the book offers a comprehensive review of the philosophical issues raised by the psychology of normal and abnormal cognition, defends the doxastic conception of delusions, and develops a theory about the role of judgements of rationality and of attributions of self-knowledge in belief ascription. Presenting a highly original analysis of the debate on the nature of delusions, this book will interest philosophers of mind, epistemologists, philosophers of science, cognitive scientists, psychiatrists, and mental health professionals.

Some otherwise rational people appear to believe strange things. Sometimes people believe that someone, usually a near relative or member of their family - often their spouse - has been replaced by an impostor. Sometimes people believe that they are dead. These two delusions – known as the Capgras and Cotard delusion respectively – are instances of monothematic delusions, for they are limited to very specific topics. Other monothematic delusions involve the delusion that one is being followed by known people in disguise (the Frégoli delusion), or that the person one sees in the mirror is someone else (mirrored-self misidentification). We will focus on the Capgras delusion.

Some monothematic types of delusions may arise because subjects have unusual experiences. The role of this experiential component in the pathogenesis of delusion is still not understood. Focussing on delusions of alien control, we outline a model for reality testing competence on unusual experiences. We propose that nascent delusions arise when there are local failures of reality testing performance, and that monothematic delusions arise as normal responses to these. In the course of this we address questions concerning the tenacity with which delusions are maintained, their often bizarre content, the patients' inability to dismiss them, and their often circumscribed character.