How many factors, i.e. departures from normality, are necessary to explain a delusion? Maher’s classic one-factor theory argues that the only factor is the patient’s anomalous experience, and a delusion arises as a normal explanation of this experience. The more recent two-factor theory, on the other hand, contends that a second factor is also needed, with reasoning abnormality being a potential candidate, and a delusion arises as an abnormal explanation of the anomalous experience. In the past few years, although there (...) has been an increasing number of scholars offering a variety of arguments in defence of Maher’s one-factor theory, these arguments have not been adequately addressed by two-factor theorists. This paper aims to address this gap by critically examining the arguments on three crucial issues: the intelligibility of delusions, the dissociation between anomalous experiences and delusions, and the empirical evidence of a second factor. I will argue that the Maherian notion of anomalous experience is not sufficient for explaining delusions and the two-factor theory is on the right track in its search for the missing factor in the aetiology of delusions. (shrink)

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)

Delusions are usually depicted in one of two contrasting ways. They are either characterized as harmful and dysfunctional beliefs or as fostering engagement with the environment and sometimes even psychological wellbeing in the face of psychological or biological difficulties – something which, according to some accounts, would make them biologically adaptive. It is this “adaptive hypothesis” that I focus on in this paper, by empirically investigating the adaptiveness of delusions in a sample of people suffering from OCD. The paper shows (...) that delusions in OCD entertain complex and heterogeneous relationships with psychological wellbeing and engagement with the environment, highlighting some future directions that clinical and philosophical research on the topic should take. (shrink)

Delusions are studied in two philosophical traditions: the continental or phenomenological tradition and the Anglo-American or analytic tradition. Each has its own view of delusions. Broadly stated, phenomenologists view delusions as a disturbed experience whilst most analytic researchers view them as beliefs. It is my contention that the most plausible account of delusions must ultimately incorporate valuable insights from both traditions. To illustrate the potential value of integration I provide a novel model of the Capgras delusion which describes how an (...) analytic, cognitive neuropsychological two-factor account of the Capgras delusion and the phenomenological view of delusions might be integrated. (shrink)

Confabulation is a symptom central to many psychiatric diagnoses and can be severely debilitating to those who exhibit the symptom. Theorists, scientists, and clinicians have an understandable interest in the nature of confabulation—pursuing ways to define, identify, treat, and perhaps even prevent this memory disorder. Appeals to confabulation as a clinical symptom rely on an account of memory’s function from which cases like the above can be contrasted. Accounting for confabulation is thus an important desideratum for any candidate theory of (...) memory. Many contemporary memory theorists now endorse Constructivism, where memory is understood as a capacity for constructing plausible representations of past events. Constructivism’s aim is to account for and normalize the prevalence of memory errors in everyday life. Errors are plausible constructions that, on a particular occasion have led to error. They are not, however, evidence of malfunction in the memory system. While Constructivism offers an uplifting repackaging of the memory errors to which we are all susceptible, it has troubling implications for appeals to confabulation in psychiatric diagnosis. By accommodating memory errors within our understanding of memory’s function, Constructivism runs the risk of being unable to explain how confabulation errors are evidence of malfunction. After reviewing the literature on confabulation and Constructivism, respectively, I identify the tension between them and explore how different versions of Constructivism may respond. The paper concludes with a proposal for distinguishing between kinds of false memory—specifically, between misremembering and confabulation—that may provide a route to their reconciliation. (shrink)

El problema tipológico surge al intentar definir el tipo de estado mental que subyace a los reportes de pacientes delirantes. Este artículo explora dos de los enfoques más populares a este problema en la literatura actual en filosofía de la mente. El análisis concluye que el enfoque doxástico —que conceptualiza los delirios como creencias anormales— es superior en términos conceptuales, empíricos y fenomenológicos al enfoque imaginístico, que caracteriza a los delirios como un tipo de estado mental imaginario. Finalmente, se concluye (...) con algunos de los desafíos que el enfoque necesita resolver para ampliar su alcance y poder explicativo. (shrink)

In folie à deux, a ‘primary’ patient transmits a delusional belief to one or more ‘secondary’ patients who then adopt and share the belief. This paper applies the two‐factor theory of delusion to retrospectively analyse published cases of folie à deux. Lessons from this retrospective analysis include, firstly, that two‐factor theorists need to shift their focus from endogenous processes to consider the exogenous source of delusional content in most secondaries. Secondly, secondaries who come to share the belief via normal processes (...) of social contagion only qualify as delusional by virtue of the abnormal persistence of their belief, albeit a temporary persistence in those secondaries who abandon their belief soon after separation from the primary. Underpinning this abnormal persistence may be a form of inhibitory failure—a difficulty with inhibiting a belief to allow reasoning for and against it being true. (shrink)

Superstition and confabulation are extremely pervasive in our cognitive lives. Whilst both these phenomena are widely discussed in the recent psychological literature, however, the relationship between them has not been the object of much explicit attention. In this paper, I argue that this relationship is actually very close, and deserves indepth consideration. I argue that superstitious and confabulatory attitudes share several key features and are rooted in the same psychological mechanisms. Moreover, some of the key features that superstitious and confabulatory (...) attitudes share reveal such attitudes to be non-doxastic in nature, with important implications for our assessment of their epistemic rationality. Many instances of what we call superstitious and confabulatory ‘beliefs’ are not, in fact, beliefs; hence, entertaining them may be less irrational than it prima facie seems to be. (shrink)

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)

There is evidence indicating that the Capgras delusion is grounded in some kind of anomalous experience. According to the endorsement model, the content of the delusion is already encoded in the Capgras subject's experience, and the delusion is formed simply by endorsing that content as veridical. Elisabeth Pacherie and Sam Wilkinson have in different ways attempted to articulate a comprehensive defence of this strategy, but here I argue that the endorsement model cannot be defended along the lines envisioned by either (...) of them. I then offer a more promising way of spelling out the model, according to which the anomalous experience implicated in Capgras is metaphorical in character. (shrink)