Jennifer Radden argues that delusions play an important role in modernist epistemology, which is preoccupied with the justification and evaluation of beliefs. Another theme running through the book is the importance of culture for attribution of delusion. Beliefs that look delusional will not be treated as pathological if they are expressions of religious views or other culturally acceptable forms of life. It is hard to see why cultural acceptability should play a role in the modernist project of justification. I suggest (...) that we think less about a philosophical project of justification and turn our attention instead to commonsense judgements of the circumstances in which we see a belief as evidence of underlying pathology. I discuss cases in which unjustified beliefs are nonetheless treated as phenomena that are consistent with our views of how healthy human beings act, and suggest that alongside folk psychology we should acknowledge a folk epistemology that embraces such instances. I suggest that delusions are beliefs that folk epistemology treats as inexplicable, and that this approach solves some of the puzzles that Radden identifies as growing out of the modernist epistemic project. (shrink)

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)

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.

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)

Biological functions are dispositions or effects a trait has which explain the recent maintenance of the trait under natural selection. This is the "modern history" approach to functions. The approach is historical because to ascribe a function is to make a claim about the past, but the relevant past is the recent past; modern history rather than ancient.

This paper is a critical analysis of the concept of mental disorder recently advanced by Jerome Wakefield. Wakefield suggests that mental disorders are most aptly conceived as "harmful dysfunctions" involving two distinct and separable components: the failure of the mechanism in the person to perform a natural function for which the mechanism was designed by natural selection, and a value judgment that the dysfunction is undesirable.

Considers that intuitive predictions follow a judgmental heuristic-representativeness. By this heuristic, people predict the outcome that appears most representative of the evidence. Consequently, intuitive predictions are insensitive to the reliability of the evidence or to the prior probability of the outcome, in violation of the logic of statistical prediction. The hypothesis that people predict by representativeness was supported in a series of studies with both naive and sophisticated university students. The ranking of outcomes by likelihood coincided with the ranking by (...) representativeness, and Ss erroneously predicted rare events and extreme values if these happened to be representative. The experience of unjustified confidence in predictions and the prevalence of fallacious intuitions concerning statistical regression are traced to the representativeness heuristic. (shrink)

What factors should be taken into account when attributing criminal responsibility to perpetrators of severe crimes? We discuss the Breivik case, and the considerations which led to holding Breivik accountable for his criminal acts. We put some pressure on the view that experiencing certain psychiatric symptoms or receiving a certain psychiatric diagnosis is sufficient to establish criminal insanity. We also argue that the presence of delusional beliefs, often regarded as a key factor in determining responsibility, is neither necessary nor sufficient (...) for criminal insanity. (shrink)

The impact of our desires and preferences upon our ordinary, everyday beliefs is well-documented [Gilovich, T. . How we know what isn’t so: The fallibility of human reason in everyday life. New York: The Free Press.]. The influence of such motivational factors on delusions, which are instances of pathological misbelief, has tended however to be neglected by certain prevailing models of delusion formation and maintenance. This paper explores a distinction between two general classes of theoretical explanation for delusions; the motivational (...) and the deficit. Motivational approaches view delusions as extreme instances of self-deception; as defensive attempts to relieve pain and distress. Deficit approaches, in contrast, view delusions as the consequence of defects in the normal functioning of belief mechanisms, underpinned by neuroanatomical or neurophysiological abnormalities. It is argued that although there are good reasons to be sceptical of motivational theories , recent experiments confirm that motives are important causal forces where delusions are concerned. It is therefore concluded that the most comprehensive account of delusions will involve a theoretical unification of both motivational and deficit approaches. (shrink)

In instances of "twisted" self-deception, people deceive themselves into believing things that they do not want to be true. In this, twisted self-deception differs markedly from the "straight" variety that has dominated the philosophical and psychological literature on self-deception. Drawing partly upon empirical literature, I develop a trio of approaches to explaining twisted self-deception: a motivation-centered approach; an emotion-centered approach; and a hybrid approach featuring both motivation and emotion. My aim is to display our resources for exploring and explaining twisted (...) self-deception and to show that promising approaches are consistent with a plausible position on straight self-deception. (shrink)

To what extent do self-deception and delusion overlap? In this paper we argue that both self-deception and delusions can be understood in folk-psychological terms. “Motivated” delusions, just like self-deception, can be described as beliefs driven by personal interests. If self-deception can be understood folk-psychologically because of its motivational component, so can motivated delusions. Non-motivated delusions also fit the folk-psychological notion of belief, since they can be described as hypotheses one endorses when attempting to make sense of unusual and powerful experiences. (...) We suggest that there is continuity between the epistemic irrationality manifested in self-deception and in delusion. (shrink)

This chapter contains section titles: Introduction Response Functions Information and Singular Causation The Functions of Sensory Representations The Contents of Sensory Representations: The Problem of Error The Contents of Sensory Representation: The Distality Problem.

Formulations of the essential commitment of the etiological theory of functions have varied significantly, with some individual authors' formulations even varying from one place to another. The logical geography of these various formulations is different from what is standardly assumed; for they are not stylistic variants of the same essential commitment, but stylistic variants of two non-equivalent versions of the etiological theory. I distinguish these “strong” and “weak” versions of the etiological theory (which differ with respect to the role of (...) selection in their definitions of function), draw out their respective implications, and argue that the weak version is to be preferred to the strong. (shrink)

In their target article, McKay & Dennett (M&D) conclude that only “positive illusions” are adaptive misbeliefs. Relying on overly strict conceptual schisms (deficit vs. motivational, functional vs. organic, perception vs. belief), they prematurely discount delusions asbiologicallyadaptive. In contrast to their view that “motivation” plays a psychological but not a biological function in a two-factor model of the forming and maintenance of delusions, we propose asingleimpairment in prediction-error–driven (i.e., motivational) learning in three stages in which delusions play a biologically adaptive role.

We describe delusional disorder–jealous type (“morbid jealousy”) with the adaptationist perspective used by Darwinian psychiatrists and evolutionary psychologists to explain the relatively common existence and continued prevalence of mental disorders. We then apply the “harmful dysfunction” analysis to morbid jealousy, including a discussion of this disorder as (1) an end on a continuum of normal jealousy or (2) a discrete entity. (Published Online November 9 2006).

The harmful dysfunction (HD) analysis of "disorder" holds that disorders are harmful failures of "designed" (that is, naturally selected) functions. Murphy and Woolfolk (2000) present a series of proposed counterexamples to the HD analysis to support their claim that it fails to provide a necessary condition for disorder. They argue that disorder can exist where there is no failed function, as in failed spandrels and inflamed vestigial organs, and that there can be disorders when everything is working as designed, as (...) in environment--design mismatches and disorders acquired through normal learning processes. They also argue that the HD analysis suffers from methodological problems, including value-ladenness of dysfunction judgments and unwarranted assumptions about the nature of internal mechanisms and their functions. -/- In this paper, each of these objections is critically evaluated. Reanalysis of the proposed counterexamples is argued to reveal strong support for the HD analysis. For example, failed spandrels are considered disorders when and only when they imply failures of designed functions; dysfunctions of vestigial organs involve failures of function at the tissue level, not the organ level; mechanism-environment mismatches are not considered disorders; and conditions acquired through normal learning processes can involve dysfunctions and are considered disordered only when they do. Murphy and Woolfolk's methodological objections are found to be based on a misinterpretation of the HD analysis. It is concluded that Murphy and Woolfolk fail to offer a cogent objection to the HD analysis. (shrink)

The "teleosemantic" program is part of the attempt to give a naturalistic explanation of the semantic properties of mental representations. The aim is to show how the internal states of a wholly physical agent could, as a matter of objective fact, represent the world beyond them. The most popular approach to solving this problem has been to use concepts of physical correlation with some kinship to those employed in information theory (Dretske 1981, 1988; Fodor 1987, 1990). Teleosemantics, which tries to (...) solve the problem using a concept of biological function, arrived in the mid 1980s with ground-breaking works by Millikan (1984) and Papineau (1984, 1987).¹. (shrink)

"Paleontologists like to say that to a first approximation, all species are extinct (ninety- nine percent is the usual estimate). The organisms we see around us are distant cousins, not great grandparents; they are a few scattered twig-tips of an enormous tree whose branches and trunk are no longer with us." (p. 343-44). The historical life bush consists mainly in dead ends.

Steven Pinker (1995) chides the educated layman for imagining Darwin's theory to go this way (the vertical lines are "begats"): [Figure #1] Pinker says, "evolution did not make a ladder; it made a bush" (p. 343), and he gives us the following diagrams instead, showing how it went, in increasing detail, down to us.