Does the formation of delusions involve abnormal reasoning? According to the prominent ‘two-factor’ theory of delusions (e.g. Coltheart, 2007), the answer is yes. The second factor in this theory is supposed to affect a deluded individual's ability to evaluate candidates for belief. However, most published accounts of the two-factor theory have not said much about the nature of this second factor. In an effort to remedy this shortcoming, Coltheart, Menzies and Sutton (2010) recently put forward a Bayesian account of inference (...) in delusions. I outline some criticisms of this important account, and sketch an alternative account of delusional inference that, I argue, avoids these criticisms. Specifically, I argue that the second factor in delusion formation involves a systematic deviation from Bayesian updating, a deviation that may be characterized as a bias towards ‘explanatory adequacy’. I present a numerical model of this idea and show that my alternative account is broadly consistent with prominent prediction error models of delusion formation (e.g. Corlett, Murray et al., 2007). (shrink)

Cognitive approaches contribute to our understanding of delusions by providing an explanatory framework that extends beyond the personal level to the sub personal level of information-processing systems. According to one influential cognitive approach, two factors are required to account for the content of a delusion, its initial adoption as a belief, and its persistence. This chapter reviews Bayesian developments of the two-factor framework.

Recreative Minds develops a philosophical theory of imagination that draws upon the latest work in psychology. This theory illuminates the use of imagination in coming to terms with art, its role in enabling us to live as social beings, and the psychological consequences of disordered imagination. The authors offer a lucid exploration of a fascinating subject.

Drawing on the latest work in cognitive neuroscience, a philosopher proposes that delusions are narrative models that accommodate anomalous experiences.

Bortolotti argues that the irrationality of many delusions is no different in kind from the irrationality that marks many non-pathological states typically treated as beliefs. She takes this to secure the doxastic status of those delusions. Bortolotti’s approach has many benefits. For example, it accounts for the fact that we can often make some sense of what deluded subjects are up to, and helps explain why some deluded subjects are helped by cognitive behavioral therapy. But there is an alternative approach (...) that secures the same benefits as Bortolotti’s account while bringing additional benefits. The alternative approach treats both many delusions and many of the non-pathological states to which Bortolotti compares them as in-between states. Subjects in in-between states don’t fully believe the beliefs which it is sometimes convenient to ascribe to them. This alternative approach to belief and belief-ascription fits well with an independently attractive account of the varied purposes of our ordinary attitude ascriptions. It also makes it easier to make fine-grained distinctions between intentional attitudes of different kinds. (shrink)

We argue that the most plausible characterisation of the norm of truth—it is permissible to believe that p if and only if p is true—is unable to explain Transparency in doxastic deliberation, a task for which it is claimed to be equipped. In addition, the failure of the norm to do this work undermines the most plausible account of how the norm guides belief formation at all. Those attracted to normativism about belief for its perceived explanatory credentials had better look (...) elsewhere. (shrink)

Why, when asking oneself whether to believe that p, must one immediately recognize that this question is settled by, and only by, answering the question whether p is true? Truth is not an optional end for first-personal doxastic deliberation, providing an instrumental or extrinsic reason that an agent may take or leave at will. Otherwise there would be an inferential step between discovering the truth with respect to p and determining whether to believe that p, involving a bridge premise that (...) it is good (in whichever sense of good one likes, moral, prudential, aesthetic, allthings-considered, etc.) to believe the truth with respect to p. But there is no such gap between the two questions within the first-personal deliberative perspective; the question whether to believe that p seems to collapse into the question whether p is true. (shrink)

“Mad belief” (in analogy with Lewisian “mad pain”) would be a belief state with none of the causal role characteristic of belief—a state not caused or apt to have been caused by any of the sorts of events that usually cause belief and involving no disposition toward the usual behavioral or other manifestations of belief. On token-functionalist views of belief, mad belief in this sense is conceptually impossible. Cases of delusion—or at least some cases of delusion—might be cases of belief (...) gone half-mad, cases in which enough of the functional role characteristic of belief is absent that the subject is in an “in-between” state regarding the delusive content, such that it is neither quite right to say the subject determinately believes the delusive content nor quite right to say that she determinately fails to believe that content. Although Bortolotti (2010) briefly mentions such “sliding scale” approaches to the relationship of delusion and belief, she dismisses such approaches on rather thin grounds and then later makes some remarks that seem consonant with sliding scale approaches. (shrink)

This paper describes and defends in detail a novel account of belief, an account inspired by Ryle's dispositional characterization of belief, but emphasizing irreducibly phenomenal and cognitive dispositions as well as behavioral dispositions. Potential externalist and functionalist objections are considered, as well as concerns motivated by the inevitably ceteris paribus nature of the relevant dispositional attributions. It is argued that a dispositional account of belief is particularly well-suited to handle what might be called "in-between" cases of believing - cases in (...) which it is neither quite right to describe a person as having a particular belief nor quite right to describe her as lacking it. (shrink)

Dispositionalism about belief has had a recent resurgence. In this paper we critically evaluate a popular dispositionalist program pursued by Eric Schwitzgebel. Then we present an alternative: a psychofunctional, representational theory of belief. This theory of belief has two main pillars: that beliefs are relations to structured mental representations, and that the relations are determined by the generalizations under which beliefs are acquired, stored, and changed. We end by describing some of the generalizations regarding belief acquisition, storage, and change.

What is involved in the consciousness of a conscious, "occurrent" propositional attitude, such as a thought, a sudden conjecture or a conscious decision? And what is the relation of such consciousness to attention? I hope the intrinsic interest of these questions provides sufficient motivation to allow me to start by addressing them. We will not have a full understanding either of consciousness in general, nor of attention in general, until we have answers to these questions. I think there are constitutive (...) features of these states which can be identified by broadly philosophical investigation, and in the early part of this paper I will try to do some of that identification. -/- Beyond the intrinsic interest of the topic, the nature of such conscious attitudes is highly pertinent to a philosophical account of psychological self-knowledge. So I will also say something about the significance of the constitutive features of these conscious attitudes for a philosophical account of how it can be that a thinker has a distinctive kind of knowledge of some of his mental states. The general challenge in this area is to find anything intermediate between the unexceptionable but uninformative, on the one hand, and the absolutely unbelievable on the other. (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)

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.

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.

On many of the idealized models of human cognition and behavior in use by philosophers, agents are represented as having a single corpus of beliefs which (a) is consistent and deductively closed, and (b) guides all of their (rational, deliberate, intentional) actions all the time. In graded-belief frameworks, agents are represented as having a single, coherent distribution of credences, which guides all of their (rational, deliberate, intentional) actions all of the time. It's clear that actual human beings don't live up (...) to this idealization. The systems of belief that we in fact have are fragmented. Rather than having a single system of beliefs that guides all of our behavior all of the time, we have a number of distinct, compartmentalized systems of belief, different ones of which drive different aspects of our behavior in different contexts. It's tempting to think that, while of course people are fragmented, it would be better (from the perspective of rationality) if they weren't, and the only reason why our fragmentation is excusable is that we have limited cognitive resources, which prevents us from holding too much information before our minds at a time. Give us enough additional processing capacity, and there'd be no justification for any continued fragmentation. I argue that this is not so. There are good reasons to be fragmented rather than unified, independent of the limitations on our available processing power. In particular, there are ways our belief-forming mechanisms—including our perceptual systems—could be constructed that would make it better to be fragmented than to be unified. And there are reasons to think that some of our belief-forming mechanisms really are constructed that way. (shrink)

* [Irrationality]: ___ Irrationality, like rationality, is a normative concept. Someone who acts or reasons irrationally, or whose beliefs or emotions are irrational, has departed from a standard.

Summary To judge a belief, emotion, or action irrational is to make a normative judgment. Can such judgments be objective? It is argued that in an important class of cases they can be. The cases are those in which a person has a set of attitudes which are inconsistent by his or her own standards, and those standards are constitutive of the attitudes. Constitutive standards are standards with which an agents' attitudes and intentional actions must generally accord if judgments of (...) irrationality are to be intelligible.RésuméJuger irrationnelles une croyance, une émotion ou une action, c'est faire un jugement normatif. De tels jugements peuvent‐ils ětre objectifs? On montre qu'ils peuvent l'ětre dans une classe importante de cas: ceux où une personne a un ensemble d'attitudes qui sont inconsistantes avec ses propres normes, ces normes étant constitutives des attitudes considérées. Les normes constitutives sont des normes avec lesquelles les attitudes et les actions intentionnelles des agents doivent s'accorder pour que les jugements d'irrationalité deviennent intelligibles.ZusammenfassungWenn wir einen Glauben, eine Emotion oder eine Handlung als irrational beurteilen, so fällen wir ein normatives Urteil. Kann ein solches objektiv sein? Es wird argumentiert, dass dies für eine wichtige Klasse von Fällen zutrifft. Die Fälle sind diejenigen, in welchen eine Person eine Menge von Haltungen hat, die nach ihren eigenen Massstäben unvereinbar sind, und wo diese Massstäbe für die Haltungen konstitutiv sind. Konstitutive Massstäbe sind solche, mit denen die Haltungen und absichtlichen Handlungen des Handelnden im allgemeinen übereinstimmen müssen, wenn Urteile über Irrationalität verständlich sein sollen. (shrink)

Chris Frith has argued that a loss of the sense of agency is central to schizophrenia. This suggests a connection between hallucinations and delusions on the one hand, and the misidentification of the subject’s imaginings as perceptions and beliefs on the other. In particular, understanding the mechanisms that underlie imagination may help us to explain the puzzling phenomena of thought insertion and withdrawal. Frith sometimes states his argument in terms of a loss of metarepresentational capacity in schizophrenia. I argue that (...) this formulation is unhelpful. (shrink)

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. (shrink)

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. (shrink)

Why, when asking oneself whether to believe that p, must one immediately recognize that this question is settled by, and only by, answering the question whether p is true? Truth is not an optional end for first-personal doxastic deliberation, providing an instrumental or extrinsic reason that an agent may take or leave at will. Otherwise there would be an inferential step between discovering the truth with respect to p and determining whether to believe that p, involving a bridge premise that (...) it is good to believe the truth with respect to p. But there is no such gap between the two questions within the first-personal deliberative perspective; the question whether to believe that p seems to collapse into the question whether p is true. (shrink)