Stanford Encyclopedia Entry on Delusions.

Anorexia nervosa involves seemingly irrational beliefs about body size and the value of thinness. Historically, researchers and clinicians have avoided referring to such beliefs as delusions, instead opting for the label ‘overvalued ideas’. I discuss the relationship between the beliefs associated with anorexia nervosa and the distinction between delusions and overvalued ideas, as it is conceived in both European and American psychiatric traditions. In doing so, I question the benefit of applying the concepts of delusion and overvalued idea to anorexia (...) nervosa and raise some issues with contemporary use of the Brown Assessment of Beliefs scale for assessing the level of delusionality associated with the disorder. (shrink)

The main claim of this paper is that Andy Clark's most influential argument for ‘the extended mind thesis’ (EM henceforth) fails. Clark's argument for EM assumes that a certain form of common-sense functionalism is true. I argue, contra Clark, that the assumed brand of common-sense functionalism does not imply EM. Clark's argument also relies on an unspoken, undefended and optional assumption about the nature of mental kinds—an assumption denied by the very common-sense functionalists on whom Clark's argument draws. I also (...) critique Mark Sprevak's reductio of Clark's argument. Sprevak contends that Clark's argument does not merely entail EM; it entails an extended mind thesis so strong as to be absurd. He goes on to claim that Clark's argument should properly be viewed as a reductio of the very common-sense functionalism on which it depends. Sprevak's argument shares the flaw that afflicts Clark's argument, or so I claim. (shrink)

Kengo Miyazono’s Delusions and Beliefs: A Philosophical Inquiry is an attempt to provide a unified account of the nature, pathology, and etiology of delusions. The strength of his book resides in the clarity of arguments and its consistent adoption of a biological explanation of delusions, based on teleo-functionalism about mental states. However, there are some weaknesses in each of his arguments regarding the nature, pathology, and etiology of delusions. Regarding the nature of delusions, teleo-functionalism makes it difficult to confirm that (...) delusions are beliefs. Regarding the pathology of delusions, I suggest that the existence of harmful malfunction is a necessary but not a sufficient condition for a belief to be considered pathological, and that additional evidence is needed to justify the separation of the belief and the holder’s personhood. Regarding the etiology, it is not reasonable to incorporate the prediction error theory into a kind of two-factor theory. Therefore, the details of his arguments require further modification. (shrink)

Just as sadness is not always a symptom of mood disorder, irrational beliefs are not always symptoms of illness. Pathological irrational beliefs are distinguished from non-pathological ones by considering whether their existence is best explained by assuming some underlying dysfunctions. The features from which to infer the pathological nature of irrational beliefs are: un-understandability of their progression; uniqueness; coexistence with other psycho-physiological disturbances and/or concurrent decreased levels of functioning; bizarreness of content; preceding organic diseases known to be associated with irrational (...) beliefs; treatment response to medical intervention, etc. Severe irrationality is sometimes caused by normal human motivation rather than by mental or physical dysfunction. Pure forms of self-deception may satisfy the diagnostic criteria of delusional disorder, but there may be no evidence that suggests that they are caused by illness. Although those with pathological delusions do not recognize their delusions as symptomatic of illness, differentiating pathological beliefs from normal irrational beliefs is vitally important: If a belief is pathological, psychiatrists must seriously consider treating the patient against her will. If it is not pathological, conversely, involuntary treatments are prohibited because they offend her basic autonomy. (shrink)

People suffering from severe monothematic delusions, such as Capgras, Fregoli, or Cotard patients, regularly assert extraordinary and unlikely things. For example, some say that their loved ones have been replaced by impostors. A popular view in philosophy and cognitive science is that such monothematic delusions aren't beliefs because they don't guide behaviour and affect in the way that beliefs do. Or, if they are beliefs, they are somehow anomalous, atypical, or marginal beliefs. We present evidence from five studies that folk (...) psychology unambiguously views monothematic delusions as stereotypical beliefs. This calls into question widespread assumptions in the professional literature about belief's stereotypical functional profile. We also show that folk psychology views delusional patients as holding contradictory beliefs. And we show that frequent assertion is a powerful cue to belief ascription, more powerful than even a robust and consistent track record of non-verbal behaviour. (shrink)

Zygon®, Volume 56, Issue 4, Page 846-873, December 2021.

The central hypothesis of this book, Delusions and Beliefs: A Philosophical Inquiry (Routledge, 2019), is that delusions are malfunctional beliefs (Chapter 1); they belong to the category of belief (Chapter 2) but, unlike mundane false or irrational beliefs, they fail to perform some functions of belief (Chapter 3). More precisely, delusions directly or indirectly involve some malfunctioning cognitive mechanisms, which is empirically supported by the two-factor account of delusion formation (Chapter 4).

Rationalist accounts of self-knowledge are motivated in important part by the claim that only by looking to our reasons to discover our beliefs and desires are we active in relation to them and only thereby do we take responsibility for them. These kinds of account seem to predict that self-knowledge generated using third-personal methods or analogues of these methods will tend to undermine the capacity to exercise self-control. In this light, the insistence by treatment programs that addicts acknowledge that they (...) are addicts seems puzzling. I argue that because addicts—and perhaps ordinary akratics, to some extent at least, too—are vulnerable to losing control of their actions via losing control over their beliefs, advising them to look to their reasons for actions is counterproductive and facilitates loss of control. In contrast, an insistence on what I call impersonal self-knowledge, knowledge of some of one's states and dispositions generated by third-personal means, may help to reestablish control. (shrink)

Addiction is almost universally held to be characterized by a loss of control over drug-seeking and consuming behavior. But the actions of addicts, even of those who seem to want to abstain from drugs, seem to be guided by reasons. In this paper, I argue that we can explain this fact, consistent with continuing to maintain that addiction involves a loss of control, by understanding addiction as involving an oscillation between conflicting judgments. I argue that the dysfunction of the mesolimbic (...) dopamine system that typifies addictions causes the generation of a mismatch between the top-down model of the world that reflects the judgment that the addict ought to refrain from drugs, and bottom-up input caused by cues predictive of drug availability. This constitutes a powerful pressure toward revising the judgment and thereby attenuating the prediction error. But the new model is not stable, and shifts under the pressure of bottom-up inputs in different contexts; hence the oscillation of all-things-considered judgment. Evidence from social psychology is adduced, to suggest that a similar process may be involved in ordinary cases of weakness of will. (shrink)

In this paper, I argue (1) that the contents of some delusions are believed with sufficient confidence; (2) that a delusional subject could have a conscious belief in the content of his delusion (p), and concurrently judge a contradictory content (not-p) – his delusion could be transparent (Krstić 2020), and (3) that the existence of even one such case reveals a problem with pretty much all existing accounts of lying, since it suggests that one can lie by asserting what one (...) consciously and confidently believes is true, and (4) sincerity, since it suggests that asserting a proposition you believe is true is neither sufficient nor necessary for sincerity. If I am right about (1) and (2), then (3) and (4) follow easily. Therefore, the paper is mainly devoted to an analysis of transparent delusion and defending (1) and (2). (shrink)

In this paper, I examine a kind of delusion in which the patients judge that their occurrent thoughts are false and try to abandon them precisely because they are false, but fail to do so. I call this delusion transparent, since it is transparent to the sufferer that their thought is false. In explaining this phenomenon, I defend a particular two-factor theory of delusion that takes the proper integration of relevant reasoning processes as vital for thought-evaluation. On this proposal, which (...) is a refinement of Gerrans’s account of delusion as unsupervised by decontextualized processing, I can have all my reasoning processes working reliably and thus judge that my delusion is false but, if I cannot use their outputs when revising the thought itself, the delusion will persist. I also sketch how this framework explains some interesting cases of failed belief-revision in the general population in which people judge that ~p but nonetheless continue to believe that p. (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.

Empiricist models explain delusional beliefs by identifying the abnormal experiences which ground them. Recently, this strategy has been adopted to explain the false body size beliefs of anorexia nervosa patients. As such, a number of abnormal experiences of body size which patients suffer from have been identified. These oversized experiences convey false information regarding the patients’ own bodies, indicating that they are larger than reality. However, in addition to these oversized experiences, patients are also exposed to significant evidence suggesting their (...) bodies are in fact thin. This situation poses a conundrum: why do patients appear strongly influenced by the former kinds of evidence while the latter has little effect? To solve this conundrum, I suggest a two-factor account. First, I discuss research on the biases patients exhibit in how they gather, attend to and interpret evidence related to their own body size. Such biases in evidence treatment, I suggest, cause oversized experiences to be sought out, attended to and accepted, while veridical body size experiences are ignored or explained away. These biases constitute the second factor for this empiricist model, accounting for the unwarranted conviction with which these beliefs are held. Finally, in line with recent research into self-deception, I propose that, paradoxically, these biases in evidence treatment arise from patients’ own desires. (shrink)

In this paper we review two debates in the current literature on clinical delusions. One debate is about what delusions are. If delusions are beliefs, why are they described as failing to play the causal roles that characterise beliefs, such as being responsive to evidence and guiding action? The other debate is about how delusions develop. What processes lead people to form delusions and maintain them in the face of challenges and counter-evidence? Do the formation and maintenance of delusions require (...) abnormal experience alone, or also reasoning biases or deficits? We hope to show that the focus on delusions has made a substantial contribution to the philosophy of the mind and continues to raise issues that are central to defining the concept of belief and gaining a better understanding of how people process information and learn about the world. (shrink)

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.

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)

The Spinozan theory of belief fixation holds that mentally representing truth-apt propositions leads to immediately believing them. In this paper, I explore how the theory fares as a defence of doxasticism about delusions (the view that they are beliefs). Doxasticism has been criticised on the grounds that delusions typically do not abide by rational standards that 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. (shrink)

The present thesis surveys different philosophical approaches to the nature of delusions: specifically, their ontology. However, since none of the various theories of the nature of delusions succeeds, I argue that there must be something problematic about the form of the analyses commonly offered. My general conclusion is that one cannot characterize delusions without taking away what it is distinctive about them.