Delusions

Shaili Jain's The Unspeakable Mind is an impressive examination of the stress experienced by a veteran community that too often is handled with a sense of clinical sterility that borders on inhumanity, or a that of pandering condescension. However, what is striking about Jain's text is the lack of analysis of how trauma manifests in what Heidegger would refer to as average everydayness. In this essay I interrogate average everyday manifestations and ideal manifestations of trauma using a comparative lens. By (...) doing so, and by examining my own process of engagement after such experiences, I hope to develop the discussion surrounding post-traumatic stress in such a way that more nuanced methodologies of healing can be illuminated. (shrink)

Ideology is commonly defined along functional, epistemic, and genetic dimensions. This article advances a reasonably unified account that specifies how they connect and locates the mechanisms at work. I frame the account along a recent distinction between anchoring and grounding, endorse an etiological reading of functional explanations, and draw on current work about the epistemology of delusion, looping effects, and structuring causes to explain how ideologies originate, reproduce, and possibly collapse. This eventually allows articulating how the legitimating function of ideologies (...) relates to the constitutive and causal role they play when embedded into the facts they are originally designed to anchor. (shrink)

Various psychopathologies of self-awareness, such as somatoparaphrenia and thought insertion in schizophrenia, might seem to threaten the viability of the higher-order thought (HOT) theory of consciousness since it requires a HOT about one’s own mental state to accompany every conscious state. The HOT theory of consciousness says that what makes a mental state a conscious mental state is that there is a HOT to the effect that “I am in mental state M.” I have argued in previous work that a (...) HOT theorist can adequately respond to this concern with respect to somatoparaphrenia and thought insertion. There is also Cotard syndrome which is a rare neuropsychiatric disorder in which people hold the delusional belief that they are dead, do not exist, or have lost their blood or internal organs. In this paper, I argue that HOT theory has nothing to fear from it either and can consistently account for what happens in such unusual cases. I analyze Cotard syndrome in light of my previous discussion of somatoparaphrenia and thought insertion, and argue that HOT theory can provide a somewhat analogous account without the worry of inconsistency. It is crucial to recognize that there are multiple “self-concepts” and levels of HOTs which can help to provide a more nuanced explanation. With regard to the connection between consciousness and self-consciousness, it is proposed that Cotard patients are indeed capable of having some “I-thoughts” about their bodies and mental states. (shrink)

Among psychiatric conditions, delusions have received significant attention in the philosophical literature. This is partly due to the fact that many delusions are bizarre, and their contents interesting in and of themselves. But the disproportionate attention is also due to the notion that by studying what happens when perception, cognition, and belief go wrong, we can better understand what happens when these go right. In this paper, I attend to delusions for the second reason—by evaluating the epistemology of delusions, we (...) can better understand the epistemology of ordinary belief. More specifically, given recent advancements in our understanding of how delusions are formed, the epistemology of delusions motivates a proper functionalist account of the justification of belief. Proper functionalist accounts of the justification of belief hold that whether a belief is justified is partly determined by whether the system that produces the belief is functioning properly. (shrink)

Somatoparaphrenia is a pathology of self characterized by the sense of alienaton from parts of one’s body. It is usually construed as a kind of delusional disorder caused by extensive right hemisphere lesions. Lesions in the temporoparietal junction are common in somatoparaphrenia but deep cortical regions (for example, the posterior insula) and subcortical regions (for example, the basal ganglia) are also sometimes implicated (Valler and Ronschi 2009). Patients are often described as feeling that a limb belongs to another person and (...) thus attribute ownership of the limb and bodily sensation to someone else. There is also some question as to whether or not the higher-order thought (HOT) theory of consciousness can plausibly account for the depersonalization psychopathology of somatoparaphrenia (Liang and Lane 2009, Rosenthal 2010, Lane and Liang 2010). Liang and Lane argue that it cannot. The HOT theory of consciousness says that what makes a mental state a conscious mental state is that it is the target of a HOT to the effect that “I am in mental state M” (Rosenthal 2005, Gennaro 2012). When the HOT is itself is unconscious, the conscious state is still outer-directed. When the HOT is conscious, we have introspection and so the conscious thought is directed at the mental state. In section I, I briefly review the previous exchange between Lane and Liang and David Rosenthal. In section II, I further explore somatoparaphrenia and the nature of delusion while offering a number of additional replies to Lane and Liang. In section III, I examine the central notions of “mental state ownership” and “self-concepts” in an effort to account especially for the depersonalization aspect of somatoparaphrenia against the background of HOT theory. In section IV, I argue that to the extent that somatoparaphrenia casts doubt on the notion that some thoughts are “immune to error through misidentification” (IEM), the most fundamental aspect of IEM is still consistent with HOT theory. Overall, I argue that HOT theory is left unscathed by the pheneomenon of somatoparaphrenia and can even help to explain what happens in these cases. (shrink)

This paper raises a slightly uncomfortable question: are some delusional subjects responsible for their delusions? This question is uncomfortable because we typically think that the answer is pretty clearly just ‘no’. However, we also accept that self-deception is paradigmatically intentional behavior for which the self-deceiver is prima facie blameworthy. Thus, if there is overlap between self-deception and delusion, this will put pressure on our initial answer. This paper argues that there is indeed such overlap by offering a novel philosophical account (...) of self-deception. The account offered is independently plausible and avoids the main problems that plague other views. It also yields the result that some delusional subjects are self-deceived. The conclusion is not, however, that those subjects are blameworthy. Rather, a distinction is made between blameworthiness and ‘attributability’. States or actions can be significantly attributable to a subject—in the sense that they are expressions of their wills—without it being the case that the subject is blameworthy, if the subject has an appropriate excuse. Understanding delusions within this framework of responsibility and excuses not only illuminates the ways in which the processes of delusional belief formation and maintenance are continuous with ‘ordinary’ processes of belief formation and maintenance, it also provides a way of understanding the innocence of the delusional subject that does not involve the denial of agency. (shrink)

Do self‐monitoring accounts, a dominant account of the positive symptoms of schizophrenia, explain auditory verbal hallucination? In this essay, I argue that the account fails to answer crucial questions any explanation of auditory verbal hallucination must address. Where the account provides a plausible answer, I make the case for an alternative explanation: auditory verbal hallucination is not the result of a failed control mechanism, namely failed self‐monitoring, but, rather, of the persistent automaticity of auditory experience of a voice. My argument (...) emphasizes the importance of careful examination of phenomenology as providing substantive constraints on causal models of the positive symptoms in schizophrenia. (shrink)

It is my contention that the table of intentionality (rationality, mind, thought, language, personality etc.) that features prominently here describes more or less accurately, or at least serves as an heuristic for, how we think and behave, and so it encompasses not merely philosophy and psychology, but everything else (history, literature, mathematics, politics etc.). Note especially that intentionality and rationality as I (along with Searle, Wittgenstein and others) view it, includes both conscious deliberative linguistic System 2 and unconscious automated prelinguistic (...) System 1 actions or reflexes. -/- I provide a critical survey of some of the major findings of two of the most eminent students of behavior of modern times, Ludwig Wittgenstein and John Searle, on the logical structure of intentionality (mind, language, behavior), taking as my starting point Wittgenstein’s fundamental discovery –that all truly ‘philosophical’ problems are the same—confusions about how to use language in a particular context, and so all solutions are the same—looking at how language can be used in the context at issue so that its truth conditions (Conditions of Satisfaction or COS) are clear. The basic problem is that one can say anything but one cannot mean (state clear COS for) any arbitrary utterance and meaning is only possible in a very specific context. I analyze various writings by and about them from the modern perspective of the two systems of thought (popularized as ‘thinking fast, thinking slow’), employing a new table of intentionality and new dual systems nomenclature. I show that this is a powerful heuristic for describing behavior. -/- Thus, all behavior is intimately connected if one takes the correct viewpoint. The Phenomenological Illusion (oblivion to our automated System 1) is universal and extends not merely throughout philosophy but throughout life. I am sure that Chomsky, Obama, Zuckerberg and the Pope would be incredulous if told that they suffer from the same problem as Hegel, Husserl and Heidegger, (or that that they differ only in degree from drug and sex addicts in being motivated by stimulation of their frontal cortices by the delivery of dopamine (and over 100 other chemicals) via the ventral tegmentum and the nucleus accumbens), but it’s clearly true. While the phenomenologists only wasted a lot of people’s time, they are wasting the earth and their descendant’s future. (shrink)

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)

I develop and defend the view that subjects are necessarily psychologically able to revise their beliefs in response to relevant counter-evidence. Specifically, subjects can revise their beliefs in response to relevant counter-evidence, given their current psychological mechanisms and skills. If a subject lacks this ability, then the mental state in question is not a belief, though it may be some other kind of cognitive attitude, such as a supposi-tion, an entertained thought, or a pretense. The result is a moderately revisionary (...) view of belief: while most mental states we thought were beliefs are beliefs, some mental states which we thought were beliefs are not beliefs. The argument for this view draws on two key claims: First, subjects are rationally obligated to revise their beliefs in response to relevant counter-evidence. Second, if some subject is rationally obligated to revise one of her mental states, then that subject can revise that mental state, given her current psychological mechanisms and skills. Along the way to defending these claims, I argue that rational obligations can govern activities which reflect on one’s rational character, whether or not those activities are under one’s voluntary control. I also show how the relevant version of epistemic ‘ought’ implies ‘can’ survives an objection which plagues other variants of the principle. (shrink)

Clinical delusions are widely characterized as being pathological beliefs in both the clinical literature and in common sense. Recently, a philosophical debate has emerged between defenders of the commonsense position (doxasticists) and their opponents, who have the burden of pointing toward alternative characterizations (anti-doxasticists). In this chapter, I argue that both doxasticism and anti- doxasticism fail to characterize the functional role of delusions while at the same time being unable to play a role in the explanation of these phenomena. I (...) also argue that though a more nuanced view of belief in which mental states are more or less belief-like instills a healthy skepticism towards the precision of folk-psychological concepts, such a stance fails to be of use in building a theory of delusion that will be able to bridge different levels of explanation, such as the phenomenology and neurobiology of delusion. Thus, I advocate moving past the question ‘Are delusions beliefs?’ and their description as propositional attitudes toward the description of the processes that generate delusion, with a view toward explaining, rather than explaining away, the personal-level aspects of the phenomenon that have been made inscrutable by investing in doxastic terminology. (shrink)

In this paper I discuss the scientific respectability of delusion as a psychiatric category. First, I present the essentialist objection to the natural kindhood of psychiatric categories, as well as non-essentialism about natural kinds as a response to that objection. Second, I present a nuanced classification of kinds of kinds. Third, drawing on the claim that the attribution of delusion relies on a folk psychological underpinning, I present the mind-dependence objection to the natural kind status of delusion. Finally, I argue (...) that even if delusion as a generic kind stands little chance of being vindicated as a non-essentialist natural kind, we stand to gain from a natural kind methodology regarding subtypes of delusion for which there is evidence of genuine causal signatures and mechanisms. (shrink)

Bortolotti argues that we cannot distinguish delusions from other irrational beliefs in virtue of their epistemic features alone. Although her arguments are convincing, her analysis leaves an important question unanswered: What makes delusions pathological? In this paper I set out to answer this question by arguing that the pathological character of delusions arises from an executive dysfunction in a subject’s ability to detect relevance in the environment. I further suggest that this dysfunction derives from an underlying emotional imbalance—one that leads (...) delusional subjects to regard some contextual elements as deeply puzzling or highly significant. (shrink)

In this paper we have two main aims. First, we present an account of mood-congruent delusions in depression (hereafter, depressive delusions). We propose that depressive delusions constitute acknowledgements of self-related beliefs acquired as a result of a negatively biased learning process. Second, we argue that depressive delusions have the potential for psychological and epistemic benefits despite their obvious epistemic and psychological costs. We suggest that depressive delusions play an important role in preserving a person’s overall coherence and narrative identity at (...) a critical time, and thus can be regarded as epistemically innocent. (shrink)

Although delusion is one of the central concepts of psychopathology, it stills eludes precise conceptualization. In this paper, I present certain basic issues concerning the classification and definition of delusion, as well as its ontological status. By examining these issues, I aim to shed light on the ambiguity of the clinical term ‘delusion’ and its extension, as well as provide clues as to why philosophers are increasingly joining the ranks of psychiatrists, psychologists, and neuroscientists in the effort to come to (...) a comprehensive understanding of delusion. (shrink)

Examino a controvérsia sobre como melhor definir o delírio—um sintoma central de patologias como a esquizofrenia e a demência—e apresentarei algumas das principais dificuldades envolvidas em sua caracterização como crenças. A partir disso, tiro conclusões sobre os limites do vocabulário mentalista da dita psicologia do senso comum e sobre a forma como delírios e outros fenômenos elusivos devem ser propriamente caracterizados pela psiquiatria para que uma explicação integrativa destes seja alcançada.

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)

There has recently been emphasis put on providing two-factor accounts of monothematic delusions. Such accounts would explain (1) whether a delusional hypothesis (e.g. someone else is inserting thoughts into my mind) can be understood as a prima facie reasonable response to an experience and (2) why such a delusional hypothesis is believed and maintained given its implausibility and evidence against it. I argue that if we are to avoid obfuscating the cognitive mechanisms involved in monothematic delusion formation we should split (...) the first factor (1 above) into two factors: how abnormal experience can give rise to a delusional ‘proto-hypothesis’ and how a ‘proto-hypothesis’ in consort with normal experiences and background information, can be developed into a delusional hypothesis. In particular I will argue that a schizophrenic is faced with the unusual requirement of having to identify an introspectively accessible thought as one's own, and that this requirement of identification is the central experiential abnormality of thought insertion, auditory verbal hallucination, and alien control (i.e. passivity symptoms). Additionally, I will consider non-experiential factors which are required for the formation of a delusional hypothesis. (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)

My central question in this paper is how delusional beliefs are related to self-deception. In section 1, I summarize my position on what self-deception is and how representative instances of it are to be explained. I turn to delusions in section 2, where I focus on the Capgras delusion, delusional jealousy (or the Othello syndrome), and the reverse Othello syndrome.

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)

Review of Eric Reitan's Is God a Delusion.

The unit of selection is the concept of that ‘something’ to which biologists refer when they speak of an adaptation as being ‘for the good of’ something. Darwin identified the organism as the unit of selection because for him the ‘struggle for existence’ was an issue among individuals. Later on it was suggested that, in order to understand the evolution of social behavior, it is necessary to argue that groups, and not individuals, are the units of selection. The last addition (...) to this debate was the formulation by Dawkins, in 1976, that the genes themselves are the units of selection while the organisms are merely the temporary receptacles and vehicles for such genes. Thus, the preposterous dissolution of the organism into genes and the proteins coded by such genes has been introduced in the evolutionary discourse by neglecting that the explanations for biological phenomena can be either synchronic or diachronic, depending on the phenomenon to be explained. Therefore explanations in molecular biology are synchronic while evolutionary biology needs diachronic explanations. Nevertheless, for ultra-Darwinians such as Dawkins, efficient replication is all that biology is about. Here I develop an argument in order to show that there is nothing in molecular and cell biology that might support such a contention and that the idea of the gene as the unit of selection is incompatible with the evident evolution of biological complexity. (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)

Delusions are defined as irrational beliefs that compromise good functioning. However, in the empirical literature, delusions have been found to have some psychological benefits. One proposal is that some delusions defuse negative emotions and protect one from low self-esteem by allowing motivational influences on belief formation. In this paper I focus on delusions that have been construed as playing a defensive function (motivated delusions) and argue that some of their psychological benefits can convert into epistemic ones. Notwithstanding their epistemic costs, (...) motivated delusions also have potential epistemic benefits for agents who have faced adversities, undergone physical or psychological trauma, or are subject to negative emotions and low self-esteem. To account for the epistemic status of motivated delusions, costly and beneficial at the same time, I introduce the notion of epistemic innocence. A delusion is epistemically innocent when adopting it delivers a significant epistemic benefit, and the benefit could not be attained if the delusion were not adopted. The analysis leads to a novel account of the status of delusions by inviting a reflection on the relationship between psychological and epistemic benefits. (shrink)

In this paper, I investigate in detail one theoretical approach to the symptom of thought insertion. This approach suggests that patients are lead to disown certain thoughts they are subjected to because they lack a sense of active participation in the occurrence of those thoughts. I examine one reading of this claim, according to which the patients’ anomalous experiences arise from a breakdown of cognitive mechanisms tracking the production of occurrent thoughts, before sketching an alternative reading, according to which their (...) experiences have to be explained in terms of a withdrawal, on the part of the patients themselves, from certain forms of active engagement in reasoning. I conclude with a discussion of the relationship between this view and the idea that patients’ reports of thought insertion reflect a situation in which the boundaries between the self and the world have become uncertain. (shrink)

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 .. (shrink)

Three challenges to a unified understanding of delusions emerge from Radden's On Delusion (2011). Here, I propose that in order to respond to these challenges, and to work towards a unifying framework for delusions, we should see delusions as arising in inference under uncertainty. This proposal is based on the observation that delusions in key respects are surprisingly like perceptual illusions, and it is developed further by focusing particularly on individual differences in uncertainty expectations.

This chapter identifies and explores a series of challenges raised by the clinical concept of delusion for theories which conceive autonomy as an agency rather than a status concept. The first challenge is to address the autonomy-impairing nature of delusions consistently with their role as grounds for full legal and ethical excuse, on the one hand, and psychopathological significance as key symptoms of psychoses, on the other. The second challenge is to take into account the full logical range of delusions, (...) which may take the form of true or false factual beliefs, positive or negative evaluations, as well as the paradoxical delusion of mental illness. The third and final challenge is to make room for non-pathological or, autonomy-preserving delusions and to offer a credible way of distinguishing between these and pathological or, autonomy-impairing delusions. By setting out these challenges, we are able to, firstly, distinguish between two separate conceptions of objectivity that may be at work in existing accounts of delusions and, secondly, to put a spotlight on an elusive yet inescapable notion of agential success that underlies our thinking about autonomy as well as mental disorder. (shrink)

Bortolotti’s Delusions and Other Irrational Beliefs defends the view that delusions are beliefs on a continuum with other beliefs. A different view is that delusions are more like illusions, that is, they arise from faulty perception. This view, which is not targeted by the book, makes it easier to explain why delusions are so alien and disabling but needs to appeal to forensic aspects of functioning.

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. (shrink)

In psychiatry some disorders of cognition are distinguished from instances of normal cognitive functioning and from other disorders in virtue of their surface features rather than in virtue of the underlying mechanisms responsible for their occurrence. Aetiological considerations often cannot play a significant classificatory and diagnostic role, because there is no sufficient knowledge or consensus about the causal history of many psychiatric disorders. Moreover, it is not always possible to uniquely identify a pathological behaviour as the symptom of a certain (...) disorder, as disorders that are likely to differ both in their causal histories and in their overall manifestations may give rise to very similar patterns of behaviour. -/- Consider delusions as an example. It wouldn’t be correct to define delusions as those beliefs people form as a result of a neurobiological deficit and a hypothesis-evaluation deficit (as some versions of the two-factor theory of delusions suggest), because for some delusions no neurobiological deficit may be found, and reasoning biases and motivational factors may be contributors to the formation of the delusion (e.g. McKay et al., 2005). Moreover, it would be a mistake to define delusions as symptoms of schizophrenia alone, because they occur also in other disorders, including dementia, amnesia, and delusional disorders. Thus, aetiological considerations may appear in the description and analysis of delusions, but do not feature prominently in their definition. -/- In this paper I argue that the surface features used as criteria for the classification and diagnosis of disorders of cognition are often epistemic in character. I shall offer two examples: confabulations and delusions are defined as beliefs or narratives that fail to meet standards of accuracy and justification. Although classifications and diagnoses based on features of people’s observable behaviour are necessary at these early stages of neuropsychiatric research, given the variety of conditions in which certain phenomena appear, I shall attempt to show that current epistemic accounts of confabulations and delusions have limitations. Epistemic criteria can guide both research and clinical practice, but fail to provide sufficient conditions for the identification of delusions and confabulations, and fail to demarcate pathological from non-pathological narratives or beliefs. -/- Another limitation of current epistemic accounts – which I shall not address here – is the excessive focus on epistemic faults of confabulations and delusions at the expense of their epistemically neutral or advantageous features (see Bortolotti and Cox, 2009). This may lead to a misconception of delusions and confabulations, and to an oversimplification in the assessment of the needs of people who require clinical treatment for their psychotic symptoms. (shrink)