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The Measure of Madness

The Measure of Madness: Philosophy of Mind, Cognitive Neuroscience, and Delusional Thought

Philip Gerrans
Copyright Date: 2014
Published by: MIT Press
Pages: 304
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  • Book Info
    The Measure of Madness
    Book Description:

    InThe Measure of Madness, Philip Gerrans offers a novel explanation of delusion. Over the last two decades, philosophers and cognitive scientists have investigated explanations of delusion that interweave philosophical questions about the nature of belief and rationality with findings from cognitive science and neurobiology. Gerrans argues that once we fully describe the computational and neural mechanisms that produce delusion and the way in which conscious experience and thought depend on them, the concept of delusional belief retains only a heuristic role in the explanation of delusion.Gerrans proposes that delusions are narrative models that accommodate anomalous experiences. He argues that delusions represent the operation of the Default Mode Network (DMN) -- the cognitive system that provides the raw material for humans' inbuilt tendency to provide a subjectively compelling narrative context for anomalous or highly salient experiences -- without the "supervision" of higher cognitive processes present in the nondelusional mind. This explanation illuminates the relationship among delusions, dreams, imaginative states, and irrational beliefs that have perplexed philosophers and psychologists for over a century. Going beyond the purely conceptual and the phenomenological, Gerrans brings together findings from different disciplines to trace the flow of information through the cognitive system, and applies these to case studies of typical schizophrenic delusions: misidentification, alien control, and thought insertion. Drawing on the interventionist model of causal explanation in philosophy of science and the predictive coding approach to the mind influential in computational neuroscience, Gerrans provides a model for integrative theorizing about the mind.

    eISBN: 978-0-262-32097-9
    Subjects: Philosophy, Psychology

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-viii)
  3. Acknowledgments
    (pp. ix-x)
  4. Introduction
    (pp. xi-xxiv)

    In 1979 three neuropsychologists reported an unusual case of delusion developed by a man following his admission to the hospital in a coma after a car accident. Prior to his accident he had exhibited signs of psychiatric illness such as paranoid delusions and auditory hallucinations. However, after his car accident, which produced extensive brain damage (including a necrotic right frontal lobe, a detail which will become important in ensuing chapters), he produced a new series of delusions. Released from the hospital after ten months, he returned home to visit his family for the weekend. After this visit, he stated that...

  5. 1 The Measure of Madness
    (pp. 1-20)

    How should we explain delusion? A constant flood of research provides information about the neural correlates of delusion at levels of resolution ranging from the molecular to the synaptic and neuroanatomical. At the same time, cognitive neuroscientists have developed information-processing theories that target the contribution to delusion of cognitive processes such as memory, perception, sensory processing, reward prediction, emotion, inference, attention, and executive functioning. Integrating all this research with the evidence gained in clinical encounters and by experimental psychologists is a project whose time is at hand. However, many theorists across the relevant disciplines argue that a fully integrative explanation...

  6. 2 Models, Mechanisms, and Cognitive Theories
    (pp. 21-42)

    The previous chapter suggested that despite the arguments of Meaning Rationalists and Neurobiological Eliminativists, personal-level psychology is not an autonomous explanatory realm. In fact, there must be an explanatory relationship between neuroscience and folk psychology (as the everyday practice of personal-level explanation is sometimes called). To take an obvious case, amnesia following traumatic brain injury drastically compromises personal-level psychology. The person with amnesia will experience and react to the world quite differently after her injury. Insofar as her beliefs and ability to deploy them in reasoning depend on memories, she will also think about the world differently. Memory loss caused...

  7. 3 The Processing Hierarchy and the Salience System
    (pp. 43-66)

    The mind is organized as a hierarchical system that uses representations of the world and its own states to control behavior. According to recently influential Bayesian theories of the mind, all levels of the cognitive hierarchy exploit the same principle: error correction (Clark 2012; Jones and Love 2011; Friston 2003). Each cognitive system uses models of its domain to predict its future informational states, given actions performed by the organism. When those predictions are satisfied, the model is reinforced; when they are not, the model is revised or updated, and new predictions are generated to govern the process of error...

  8. 4 The Default Mode Network
    (pp. 67-88)

    The main task of this chapter is to explain the properties of the default mode network (DMN)—the system that is active and relatively unsupervised in delusion. The default mode of the DMN is a resting state of a powerful simulation system that evolved to allow humans to simulate experiences in the absence of an eliciting stimulus. This capacity released us from the stimulus-bound present, allowing us to recall past experiences and imagine possible futures. Mental time travel, as this type of simulation process is now called, is an adaptation for planning. We can review and preview possible scenarios and...

  9. 5 Dreaming, Default Thinking, and Delusion
    (pp. 89-112)

    In this chapter we pursue the idea that the often-remarked, but not well-explained, similarity between dreaming and delusion results from the fact that they are both states characterized by activity in the default system unsupervised by decontextualized processes. We give a mechanistic and a cognitive explanation of similarities and dissimilarities between delusions and dreams. The mechanistic explanation adapts the AIM (Activation, Information, Mode) model of dreams and delusions developed by Hobson and collaborators. The cognitive explanation shows how automatic and controlled processes degrade in different ways when unsupervised in virtue of differences in cognitive architecture.

    That explanation distinguishes feature and...

  10. 6 The Second Factor: Default or Doxastic Incorporation
    (pp. 113-134)

    Most cognitive theories of delusion converge on the idea that perceptual or sensory processing anomalies alone are insufficient to lead to delusion. There must be an additional cognitive process involved in generating delusion. This chapter discusses the most influential account of that second factor. Thisdoxasticaccount (reflected in the clinical characterizations of the DSM) treats delusions as beliefs about the causes of experience and suggests that delusion consists in making bad inferences on the basis of sensory information. The idea that delusional patients suffer from a pervasive reasoning deficit, however, is unpersuasive. Delusions usually coexist with intact capacities for...

  11. 7 Imagination Incorporated
    (pp. 135-162)

    The “default thought” theory of delusion needs to show how default thoughts, which are essentially simulations, can come to occupy the functional role of belief, or at least enough of that role to cause an interpreter (perhaps even a self-interpreter) to conclude that the subject is acting on the basis of belief.

    The problem also arises for imaginative theorists of delusion who argue that delusions are produced by processes of imagination rather than belief fixation (Currie 2000a; Currie and Jones 2006; McGinn 2004). My solution is similar in some respects to that of imaginative theorists such as Tamar Gendler and...

  12. 8 The Sense of Agency, Lost and Found: Experience and Thought in Schizophrenic Delusion
    (pp. 163-208)

    A book on delusions would be incomplete without a discussion of schizophrenic delusions—the most common, clinically significant, and, in some ways, most baffling forms of delusion. (How can a person genuinely experience episodes of thinking that originate in someone else’s mind?) Previous chapters touched on aspects of schizophrenia in discussions of neurobiological eliminativism, the default system, doxastic and narrative theories of delusion, and dopaminergic mechanisms of salience. However, they did not attempt to provide a systematic explanation of schizophrenic delusion. That is the aim of this chapter, which focuses on delusions of alien control and the (I will argue,...

  13. 9 Louis Sass and the Schizophrenic Lifeworld
    (pp. 209-222)

    Phenomenological theories of delusion aim to make the life-world of the delusional patient intelligible, to cross that interpretative border described by Jaspers. Some phenomenologists have argued that one reason delusions seem so mysterious is the doxastic framework itself. Understood as empirical beliefs, many delusions are inscrutable. Thus, part of the phenomenological project is the development of an alternative conceptual framework for understanding delusion.

    In this chapter, I discuss one of the most interesting and subtle phenomenological accounts, developed by Louis Sass. Sass concentrates on a subset of schizophrenic delusions that are at the bizarre end of the spectrum compared to...

  14. 10 Conclusion
    (pp. 223-228)

    The preceding chapters described differences between delusional and normal cognition. Throughout, the aim has been to show that if we keep in mind the idea that the human brain implements a hierarchy of cognitive processes and describe those processes as accurately as possible, the relationship between neurobiological and personal/psychological levels of functioning becomes explicable. An accurate description of cognitive architecture allows us to see how and why manipulations and interventions at different levels produce predictable changes at other levels—why, for example, delusions might remit following antipsychotic medication, or how adverse experiences might produce very fundamental neurochemical and neuroanatomical changes....

  15. Notes
    (pp. 229-230)
  16. References
    (pp. 231-264)
  17. Index
    (pp. 265-274)