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The Measure of Madness

Philosophy of Mind, Cognitive Neuroscience, and Delusional Thought

Philip Gerrans

Publication Year: 2014

In The 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.

Published by: The MIT Press

Title Page, Other Works in the Series, Copyright

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pp. v-viii

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pp. ix-x

A complete list of people who have helped me with the ideas in this book would be extremely long. But I must make special mention of the people and places without whom it could not have been written. First, at the dawn of the millennium, Kim Sterelny, Martin Davies, and Max Coltheart initiated a research...

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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...

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1. The Measure of Madness

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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...

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2. Models, Mechanisms, and Cognitive Theories

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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...

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3. The Processing Hierarchy and the Salience System

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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...

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4. The Default Mode Network

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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...

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5. Dreaming, Default Thinking, and Delusion

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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...

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6. The Second Factor: Default or Doxastic Incorporation

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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. This...

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7. Imagination Incorporated

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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...

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8. The Sense of Agency, Lost and Found: Experience and Thought in Schizophrenic Delusion

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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...

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9. Louis Sass and the Schizophrenic Lifeworld

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pp. 209-222

Phenomenological theories of delusion aim to make the lifeworld 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...

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10. Conclusion

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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...


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pp. 229-230


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pp. 231-264


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pp. 265-274

E-ISBN-13: 9780262320979
E-ISBN-10: 0262320975
Print-ISBN-13: 9780262027557

Page Count: 304
Publication Year: 2014