Online research in philosophy

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.

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..

In Delusions and Other Irrational Beliefs, Lisa Bortolotti argues that the irrationality of delusions is no barrier to their being classified as beliefs. This comment asks how Bortolotti’s position may be affected if we accept that there are two distinct types of belief, belonging to different levels of mentality and subject to different ascriptive constraints. It addresses some worries Bortolotti has expressed about the proposed two-level framework and outlines some questions that arise for her if the framework is adopted. It also suggests that, rather than being beliefs that fail to meet the relevant standards of rationality, delusions may be non-doxastic acceptances that were never meant to meet them.

Subjects with delusions profess to believe some extremely peculiar things. Patients with Capgras delusion sincerely assert that, for example, their spouses have been replaced by impostors. Patients with Cotard’s delusion sincerely assert that they are dead. Many philosophers and psychologists are hesitant to say that delusional subjects genuinely believe the contents of their delusions.2 One way to reinterpret delusional subjects is to say that we’ve misidentified the content of the problematic belief. So for example, rather than believing that his wife is has been replaced by an impostor, we might say that the victim of Capgras delusion believes that it is, in some respects, as if his wife has been replaced by an impostor. Another is to say that we’ve misidentified the attitude that the delusional subject bears to the content of their delusion. So for example, Gregory Currie and co-authors have suggested that rather than believing that his wife has been replaced by an impostor, we should say that the victim of Capgras delusion merely imagines that his wife has been replaced by an impostor.3.

Here I summarise the main arguments in Delusions and Other Irrational Beliefs [1]. The book addresses the question whether there is a rationality constraint on belief ascription and defends a doxastic account of clinical delusions.

Lisa Bortolotti argues convincingly that opponents of the doxastic view of delusion are committed to unnecessarily stringent standards for belief attribution. Folk psychology recognises many non-rational ways in which beliefs can be caused, and our attributions of delusions may be guided by a sense that delusions are beliefs that we cannot explain in any folk psychological terms.

Here I reply to the main points raised by the commentators on the arguments put forward in my Delusions and Other Irrational Beliefs (OUP, 2009). My response is aimed at defending a modest doxastic account of clinical delusions, and is articulated in three sections. First, I consider the view that delusions are inbetween perceptual and doxastic states, defended by Jacob Hohwy and Vivek Rajan, and the view that delusions are failed attempts at believing or not-quitebeliefs, proposed by Eric Schwitzgebel and Maura Tumulty. Then, I address the relationship between the doxastic account of delusions and the role, nature, and prospects of folk psychology, which is discussed by Dominic Murphy, Keith Frankish, and Maura Tumulty in their contributions. In the final remarks, I turn to the continuity thesis and suggest that, although there are important differences between clinical delusions and non-pathological beliefs, these differences cannot be characterised satisfactorily in epistemic terms.

In some ways, someone suffering from the delusion that his or her spouse has been kidnapped and replaced with an imposter appears to believe that he or she eats dinner with an imposter every night. But the imperviousness of delusions to counter-evidence makes it hard to classify them as beliefs, and easier to classify them as imaginings. Bayne and Pacherie want to use Schwitzgebel’s dispositional account of belief to restore confidence in the doxastic character of delusion. While dispositionalism appears to allow us to classify delusions as beliefs, this allowance isn’t a robust vindication of doxasticism. The significance of the allowance can be increased by emphasizing the role of folk-psychological norms in individuating propositional attitudes. But letting those norms play a large role in the individuation of belief makes it hard to count as believers the deluded subjects who violate most such norms. Dispositionalism about belief can’t defend doxasticism about delusion.

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.

Although delusions are typically regarded as beliefs of a certain kind, there have been worries about the doxastic conception of delusions since at least Bleuler’s time. ‘Anti-doxasticists,’ as we might call them, do not merely worry about the claim that delusions are beliefs, they reject it. Reimer’s paper weighs into the debate between ‘doxasticists’ and ‘anti-doxasticists’ by suggesting that one of the main arguments given against the doxastic conception of delusions—what we might call the functional role objection—is based on a fallacy. She also draws attention to certain parallels between delusions and what she calls “nihilistic philosophical doctrines,” such as the skeptical position that we have no ..