The Blackwell Companion to Consciousness

Susan Schneider, Max Velmans, Susan Schneider, Max Velmans

• Publisher: Wiley-Blackwell
• Year: 2017
• Print ISBN: 9780470674079, 9780470674062
• eBook ISBN: 9781119002208
• Edition: 2
• Topic: Philosophy
• Subtopic: Philosophy History & Theory

Updated and revised, the highly-anticipated second edition of The Blackwell Companion to Consciousness offers a collection of readings that together represent the most thorough and comprehensive survey of the nature of consciousness available today.

• Features updates to scientific chapters reflecting the latest research in the field
• Includes 18 new theoretical, empirical, and methodological chapters covering integrated information theory, renewed interest in panpsychism, and more
• Covers a wide array of topics that include the origins and extent of consciousness, various consciousness experiences such as meditation and drug-induced states, and the neuroscience of consciousness
• Presents 54 peer-reviewed chapters written by leading experts in the study of consciousness, from across a variety of academic disciplines

Part I
The Problems of Consciousness

1
A Brief History of the Scientific Approach to the Study of Consciousness

Chris D. Frith and Geraint Rees

The Origin of Consciousness Studies: René Descartes

The attempt to develop a systematic approach to the study of consciousness begins with René Descartes (1596–1650) and his ideas still have a major influence today. He is best known for the sharp distinction he made between the physical and the mental (Cartesian dualism). According to Descartes, the body is one sort of substance and the mind another because each can be conceived in terms of totally distinct attributes. The body (matter) is characterized by spatial extension and motion, while the mind is characterized by thought. This characterization of the mind also renders it private, a precursor of the distinction between the first‐person and the third‐person perspectives. Today, most scientists do not accept dualism, instead believing that mind somehow emerges from the physical properties of the brain. However, the distinction between mind and matter is still perceived as being so clear‐cut that explaining how mind can emerge from matter, and reconciling the first‐person and third‐person perspectives, remain the hardest problems facing the student of consciousness.

Some consider that Descartes has impeded the scientific study of consciousness, since his development of dualism placed consciousness outside the domain of science. However, Descartes was an interactive dualist and, as such, was the first to think seriously about the neural correlates of consciousness. He recognized that the brain has a key role for sensory input and motor output, but this did not make it the basis of mind. He considered that non‐human animals did not have minds, but were unthinking automata for which a brain was sufficient. There is an interesting parallel here with current distinctions between conscious and unconscious processes. For Descartes, consciousness was a state of mind, with the brain having a role restricted to nonconscious processes. Nevertheless, the brain had a key role in linking matter and mind. Physical bodies in the world have an impact on the sense organs. This impact creates motion in the body’s nervous system that is somehow translated into the mind’s experience of color, sound, and other sensations. These motions are transmitted to the pineal gland where they act as cues to the rational soul, enabling this to have specific types of conscious experience or ideas. We now know that Descartes was wrong about the importance of the pineal gland. But his account is not that different from recent proposals that, for example, neural activity in the fusiform region of the brain somehow leads to the conscious experience of a face.

Descartes also made a distinction between what would now be called “bottom‐up” and “top‐down” processes. The passions, such as joy and anger, agitate and disturb the mind. Conflicts between the passions and the will occur when the body (bottom‐up) and the soul (top‐down) cause opposing movements in the pineal gland, that unique structure in the brain where mind and body interact. The interplay between top‐down and bottom‐up processes in determining the outcome of cognitive processes remains a common motif in contemporary cognitive neuroscience.

After Descartes

Since Descartes much effort was devoted in trying to put the physical and the mental back together again. Baruch Spinoza (1632–77) proposed that the mental and the physical are different aspects of the same substance (dual aspect theory), while Gottfried Leibniz (1646–1716) proposed that the mind and the body were separate substances, but constructed from the outset to run together in perfect harmony (psychophysical parallelism). George Berkeley (1685–1753) denied the possibility of mindless material substances (immaterialism). He proposed that things could only exist through being a mind or through being perceived by a mind. In contrast materialism holds that matter is fundamental and is the cause of mental events. This is an ancient idea championed by, among others, Julien Offray de la Mettrie (1709–51) in his book L’homme machine. La Mettrie extended Descartes’s idea of animals as automata to man. In particular, he proposed that conscious and voluntary processes result simply from more complex mechanisms than involuntary and instinctive processes. This is, in essence, the belief held by many of us who are searching for the neural correlates of consciousness in the twenty‐first century.

John Locke (1632–1704) and the empiricist philosophers who followed him were less concerned with the mind–body distinction and more concerned with the problem of knowledge: how the mind learns about the world. Locke contrasted outer sense, the mind’s experience of things, with inner sense, the mind’s reflective experience of its own experience of things. He also recognized the importance of the association of ideas, a concept taken further by David Hartley (1705–57) and the direct precursor of associationism in psychology. Hartley also proposed that sensations were paralleled by vibrations . . . or “elemental” particles in the nerves and brain providing the basis for physiological psychology. Thomas Reid (1710–96) developed Locke’s idea of inner sense to postulate that the mind contained a number of innate faculties. It was from these faculties that Franz Joseph Gall (1758–1828) derived his list of “powers of the mind” that he attempted to localize in the brain.

However, while the British empiricists were laying the foundation for a science of psychology, Immanuel Kant (1724–1804) was denying that such a science was possible. Kant pointed out that the scientific method requires the use of mathematics and experimentation. He considered that mathematics could not be applied to the description of mental phenomena because these phenomena vary in only one dimension – time. Likewise, experimentation could not be applied to psychology because mental phenomena are private and therefore inaccessible to experimental manipulation. If we accept Kant’s ideas, then physiology (the study of the brain) is a scientific discipline, while psychology (the study of the mind) is not. As a result of this distinction psychology was long considered not to be a proper subject for scientific enquiry, especially when restricted to the study of subjective experience. Even today, many traces of this unfortunate notion remain. For example, one of the many websites we consulted in the course of writing this chapter names people who have had an important role in the study of consciousness. The names are presented in three lists headed: Philosophers, Psychologists, and Scientists. Furthermore, a very eminent academic colleague of the authors recently informed us that he welcomed the advent of brain imaging since this technique would permit an objective (i.e., physiological) measure of happiness.

The Scientific Study of the Mental in the Nineteenth Century

The development of the methods of psychophysics in the nineteenth century can be seen as a reaction against the idea that mental phenomena are not amenable to experimental study and mathematical modeling. The key figure in the development of psychophysics was Gustav Fechner (1801–87). Fechner believed, against Descartes, that mind and body were two aspects of a single entity. He also believed, against Kant, that mental processes could be measured. His method of psychophysics (Fechner 1860) built on the demonstration by Herbart (1824) that mental experiences (sensations) vary in intensity and that there is a threshold (or limen) such that below a certain stimulus intensity there is no sensation. Fechner also built upon Weber’s concept of the just noticeable difference (JND) (Weber 1834). The JND is the smallest increase in stimulus intensity that is required to produce a change in sensation. Fechner used the JND as the unit of measurement and showed that there was a systematic relationship between JNDs (a subjective measure of sensation) and intensity of the physical signal. Across many modalities he found that the relationship between physical stimulus intensity and subjective sensation was logarithmic (the Weber‐Fechner law). He speculated that the relationship between intensity of sensation and nervous activity would also be logarithmic, but had no way of measuring nervous activity. Fechner succeeded in showing that the mental could be measured and was closely linked to the physical. He also developed some of the basic methods of experimental psychology that we still use today.

Helmholtz’s Unconscious Inferences

In parallel with the emergence of experimental psychology great advances were made in the understanding of the nervous system. A key figure in this development was Hermann Helmholtz (1821–94, enobled to von Helmholtz in 1882). Helmholtz began his studies of physiology with Johannes Müller. Like most biologists of his day, Müller was a vitalist who believed that living processes could never be reduced to the mechanical laws of physics and chemistry. Life depended on a vital force that was not susceptible to experimental investigation. In particular, he believed that the nerve impulse was a vital function that could never be measured experimentally since it was not extended in time. With proper disdain for the beliefs of his PhD supervisor, Helmholtz developed the myograph and measured the speed of travel of nerve impulses. He found that this was rather slow (~27 meters per second). The slow speed of travel of nerve impulses raised the possibility that mental processes might also be slow enough to measure, a possibility that led Donders to develop the reaction time task (see later).

Helmholtz made a particular study of the neural basis of perception (Helmholtz 1866). Müller had made the important observation (which he called the law of specific nerve energies) that sense organs cause the same subjective experience however they are stimulated. A mechanical blow to my eye, a stimulation that has nothing to do with light, nevertheless causes me to “see stars.” Müller proposed that there were specific kinds of nerves associated with each sense organ that created the subjective quality associ...

Table of contents

• Cover
• Title Page
• Table of Contents
• Notes on Contributors
• Introduction
• Part I: The Problems of Consciousness
• Part II: The Origins and Distribution of Consciousness
• Part III: Some Varieties of Conscious Experience
• Part IV: Some Contemporary Theories of Consciousness
• Part V: Some Major Topics in the Philosophy of Consciousness
• Part VI: Major Topics in the Science of Consciousness
• Topics in the Neuroscience of Consciousness
• First‐Person Contributions to the Science of Consciousness
• Resources for Students
• Index
• End User License Agreement