Abstract: I survey some of the connections between the metaphysics of the relation between mind and matter, and quantum theory’s measurement problem. After discussing the metaphysics, especially the correct formulation of physicalism, I argue that two state-reduction approaches to quantum theory’s measurement problem hold some surprises for philosophers’ discussions of physicalism. Though both approaches are compatible with physicalism, they involve a very different conception of the physical, and of how the physical underpins the mental, from what most philosophers expect. And one approach exemplifies a a problem in the definition of physicalism which the metaphysical literature has discussed only in the abstract. A version of the paper has appeared in Consciousness and Human Identity, ed. John Cornwell, OUP 1998

Abstract: Our reply is in three parts. The first part concerns some foundational issues in the debate about color realism. The second part addresses the many objections to the version of physicalism about color ("productance physicalism") defended in the target article. The third part discusses the leading alternative approaches and theories endorsed by the commentators

Abstract: Anomaloscope An instrument used for detecting anomalies of color vision. The test subject adjusts the ratio of two monochromatic lights to form a match with a third monochromatic light. The most common form of this procedure involves a Rayleigh match: a match between a mixture of monochromatic green and red lights, and a monochromatic yellow light. Normal subjects will choose a matching ratio of red to green light that falls within a fairly narrow range of values. Subjects with anomalous color vision will choose a ratio of red to green that falls outside this range, and red-green dichromats will accept any ratio of red to green as forming a match

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Abstract: A neighbor who strikes it rich evokes both admiration and envy, and a similar mix of emotions must be aroused in many neighborhoods of cognitive science when the residents look at the results of research in color perception. It provides what is probably the most widely acknowledged success story of any domain of scientific psychology: the success, against all expectation, of the opponent process theory of color perception. Initially proposed by a Ewald Hering, a nineteenth century physiologist, it drew its inspiration from the existence of opposing muscle groups. Hering thought that analogous opposing processes could explain some aspects of color perception, but the resulting theory was more complicated and less intuitive than that proposed by the great Hermann von Helmholtz. Helmholtz carried his day, but in the long run Hering turned out to be right

Abstract: Color relationalism is the view that colors are constituted in terms of relations to perceiving subjects. Among its explanatory virtues, relation- alism provides a satisfying treatment of cases of perceptual variation. But it can seem that relationalists lack resources for saying that a representa- tion of x’s color is erroneous. Surely, though, a theory of color that makes errors of color perception impossible cannot be correct. In this paper I’ll argue that, initial appearances notwithstanding, relationalism contains the resources to account for errors of color perception. I’ll conclude that worries about making room for error are worries the relationalist can meet

Abstract: In The Quest for Reality: Subjectivism and the Metaphysics of Colour [Stroud, 2000], Barry Stroud carries out an ambitious attack on various forms of irrealism and subjectivism about color. The views he targets - those that would deny a place in objective reality to the colors - have a venerable history in philosophy. Versions of them have been defended by Galileo, Descartes, Boyle, Locke, and Hume; more recently, forms of these positions have been articulated by Williams, Smart, Mackie, Ryle, and Hardin, among others. Stroud's aim is to argue not only that these writers fail to make their cases, but that no conceivable argument could ever convince us that colors are not a part of objective reality

Abstract: Byrne and Hilbert provide valuable clarification of the complexities–undreamt of by the layman–that make it hard to answer the question of what color is, and that often lead color scientists to say such remarkable and extravagant things. They emphasize at the outset that their issue is not just how to define the ordinary language term “color”: “The problem of color realism is like the investigation of what humans can digest, not the investigation of the folk category of food.” [ms p4], but then I am puzzled by a tension in the target article regarding the weight they put on our ordinary intuitions about color. The very setting of the issue as a disagreement between “color realists” and “color eliminativists” endows the everyday concept with somewhat more authority than it deserves–comparable to an imaginary debate between biologists who were “food realists” and “food eliminativists”!

Abstract: It has been suggested, on the one hand, that quantum states are just states of knowledge; and, on the other, that quantum theory is merely a theory of correlations. These suggestions are confronted with problems about the nature of psycho-physical parallelism and about how we could define probabilities for our individual future observations given our individual present and previous observations. The complexity of the problems is underlined by arguments that unpredictability in ordinary everyday neural functioning, ultimately stemming from small-scale uncertainties in molecular motions, may overwhelm, by many orders of magnitude, many conventionally recognized sources of observed ``quantum'' uncertainty. Some possible ways of avoiding the problems are considered but found wanting. It is proposed that a complete understanding of the relationship between subjective experience and its physical correlates requires the introduction of mathematical definitions and indeed of new physical laws

Abstract:   For nearly six decades, the conscious observer has played a central and essential rôle in quantum measurement theory. I outline some difficulties which the traditional account of measurement presents for material theories of mind before introducing a new development which promises to exorcise the ghost of consciousness from physics and relieve the cognitive scientist of the burden of explaining why certain material structures reduce wavefunctions by virtue of being conscious while others do not. The interactive decoherence of complex quantum systems reveals that the oddities and complexities of linear superposition and state vector reduction are irrelevant to computational aspects of the philosophy of mind and that many conclusions in related fields are ill founded

Abstract: Quantum mechanics may be formulated as Sensible Quantum Mechanics (SQM) so that it contains nothing probabilistic except conscious perceptions. Sets of these perceptions can be deterministically realized with measures given by expectation values of positive-operator-valued awareness operators. Ratios of the measures for these sets of perceptions can be interpreted as frequency- type probabilities for many actually existing sets. These probabilities gener- ally cannot be given by the ordinary quantum “probabilities” for a single set of alternatives. Probabilism, or ascribing probabilities to unconscious aspects of the world, may be seen to be an aesthemamorphic myth

Abstract: I propose a strategy for a metaphysical reduction of perceived color, that is, an identification of perceived color with properties characterizable in non-qualitative terms. According to this strategy, a description of visual experience of color, which incorporates a description of the appearance of color, is taken as a reference-fixing description. This strategy both gives a primary epistemic role to color appearance and avoids rendering color as metaphysically mysterious. I’ll also argue that given this strategy, disjunctive physicalism is the best account of perceived color

Abstract: Philosophy has long struggled to understand the nature of color. The central role color plays in our lives, in visual experience, in art, as a metaphor for emotions, has made it an obvious candidate for philosophical reflection. Understanding the nature of color, however, has proved a daunting task, despite the numerous fields that contribute to the project. Even knowing how to start can be difficult. Is color to be understood as an objective part of reality, a property of objects with a status similar to shape and size? Or is color more like pain, to be found only in experience and so somehow subjective? Or is color more like what some have said about time--that it seems real until we reflect enough, where we come ultimately to dismiss it as mere illusion? If color is more like shape and size, can we give a scientific account of it? Various strategies exist for this option--taking the color of an object to be just a complicated texture of that object, one that reflects certain wavelengths. Or perhaps color is merely a disposition to cause experiences in us, as salt has a disposition to dissolve. On the other hand, if color is more like pain, and found only in subjective experience, what is the nature of color experience? How, for instance, does an experience of red differ from an experience of blue, or from an experience of pain for that matter? Finally, if color is mere illusion, how do we continue to be so taken in by that illusion and how can something unreal seem so real and important to us?

Abstract:   The Everett interpretation of quantum theory requires either the existence of an infinite number of conscious minds associated with each brain or the existence of one universal consciousness. Reasons are given, and the two ideas are compared

Abstract:   The measurement problem of quantum theory is discussed, and the difficulty of trying to solve it within the confines of a local, Lorentz-invariant physics is emphasised. This leads to the obvious suggestion to seek a solution beyond physics, in particular, by introducing the concept of consciousness. The resulting dualistic model, in the natural form suggested by quantum theory, is shown to differ in several respects from the classical model of Descartes, and to suggest solutions to some of the long-standing problems concerning the relation of consciousness to the physical world

Abstract: _René Descartes proposed an interactive dualism that posits an interaction between the_ _mind of a human being and some of the matter located in his or her brain. Isaac Newton_ _subsequently formulated a physical theory based exclusively on the material/physical_ _part of Descartes’ ontology. Newton’s theory enforced the principle of the causal closure_ _of the physical, and the classical physics that grew out of it enforces this same principle._ _This classical theory purports to give, in principle, a complete deterministic account of the_ _physically described properties of nature, expressed exclusively in terms of these_ _physically described properties themselves. Orthodox contemporary physical theory_ _violates this principle in two separate ways. First, it injects random elements into the_ _dynamics. Second, it allows, and also requires, abrupt probing actions that disrupt the_ _mechanistically described evolution of the physically described systems. These probing_ _actions are called Process 1 interventions by von Neumann. They are psycho-physical_ _events. Neither the content nor the timing of these events is determined either by any_ _known law, or by the afore-mentioned random elements. Orthodox quantum mechanics_ _considers these events to be instigated by choices made by conscious agents. In von_ _Neumann’s formulation of quantum theory each such intervention acts upon the state of_ _the brain of some conscious agent. Thus orthodox von Neumann contemporary physics_ _posits an interactive dualism similar to that of Descartes. But in this quantum version the_ _effects of the conscious choices upon our brains are controlled, in part, by the known_ _basic rules of quantum physics. This theoretically specified mind-brain connection allows_ _many basic psychological and neuropsychological findings associated with the apparent_ _physical effectiveness of our conscious volitional efforts to be explained in a causal and_ _practically useful way..

Abstract: b>: Replacing faulty nineteenth century physics by its orthodox quantum successor converts the earlier materialist conception of nature to a structure that does not enforce the principle of the causal closure of the physical. The quantum laws possess causal gaps, and these gaps are filled in actual scientific practice by inputs from our streams of consciousness. The form of the quantum laws permits and suggests the existence of an underlying reality that is built not on substances, but on psychophysical events, and on objective tendencies for these events to occur. These events constitute intrinsic mind-brain connections. They are fundamental links between brain processes described in physical terms and events in our streams of consciousness. This quantum ontology confers upon our conscious intentions the causal efficacy assigned to them in actual scientific practice, and creates a substance- free interactive dualism. This putative quantum ontology has previously been shown to have impressive explanatory power in both psychology and neuroscience. Here it is used to reconcile the existence of physically efficacious conscious free will with causal anomalies of both the Libet and Einstein-Rosen-Podolsky types

Abstract: René Descartes proposed an interactive dualism that posits an interaction between the mind of a human being and some of the matter located in his or her brain. Isaac Newton subsequently formulated a physical theory based exclusively on the material/physical part of Descartes’ ontology. Newton’s theory enforced the principle of the causal closure of the physical, and the classical physics that grew out of it enforces this same principle. This classical theory purports to give, in principle, a complete deterministic account of the physically described properties of nature, expressed exclusively in terms of these physically described properties themselves. Orthodox contemporary physical theory violates this principle in two separate ways. First, it injects random elements into the dynamics. Second, it allows, and also requires, abrupt probing actions that disrupt the mechanistically described evolution of the physically described systems. These probing actions are called Process 1 interventions by von Neumann. They are psycho-physical events. Neither the content nor the timing of these events is determined either by any known law, or by the afore-mentioned random elements. Orthodox quantum mechanics considers these events to be instigated by choices made by conscious agents. In von Neumann’s formulation of quantum theory each such intervention acts upon the state of the brain of some conscious agent. Thus orthodox von Neumann contemporary physics posits an interactive dualism similar to that of Descartes. But in this quantum version the effects of the conscious choices upon our brains are controlled, in part, by the known basic rules of quantum physics. This theoretically specified mind-brain connection allows many basic psychological and neuropsychological findings associated with the apparent physical effectiveness of our conscious volitional efforts to be explained in a causal and practically useful way..

Abstract: Quantum mechanical theories of consciousness are contrasted to classical ones. A key difference is that the quantum laws are fundamentally psychophysical and provide an explanation of the causal effect of conscious effort on neural processes, while the laws of classical physics, being purely physical, cannot. The quantum approach provides causal explanations, deduced from the laws of physics, of correlations found in psychology and in neuropsychology

Abstract: Science is basically about correlations between conscious human experiences: that is what makes it both useful and testable in the realm of our expanding human knowledge. Explicit recognition of this understanding lies at the core of the formulation of quantum theory that was originally developed during the twenties by its founders

Abstract: Neuroscience is an important component of the scientific attack on the problem of consciousness. However, most neuroscientists, viewing our discussions, see only conflict and discord, and no reason why quantum theory has any great relevance the dynamics of the conscious brain. It is therefore worthwhile, in this first plenary talk of the 2003 Tucson conference on “Quantum Approaches to the Understanding of Consciousness,” to focus on the central issue, which is the crucial role of “The Observer,” and specifically, “The Mind of The Observer” in contemporary physical theory. I shall therefore review here this radical departure of present-day basic physics from the principles of classical physics, and then spell out some of its ramifications for neuroscience

Abstract: A central issue of cognitive neuroscience is to understand how a large collection of coupled neurons combines external signals with internal memories into new coherent patterns of meaning. An external stimulus localized at some input spreads over a large assembly of coupled neurons, building up a collective state univocally corresponding to the stimulus. Thus, the synchronization of spike trains of many individual neurons is the basis of a coherent perception. Based on recent investigations of homoclinic chaotic systems and their synchronization, a novel conjecture for the dynamics of single neurons and, consequently, for neuron assemblies is formulated. Homoclinic chaos is proposed as a suitable way to code information in time by trains of equal spikes occurring at apparently erratic times. In order to classify the set of different perceptions, the percept space can be given a metric structure by introducing a distance measure between distinct percepts. The distance in percept space is conjugate to the duration of the perception in the sense that an uncertainty relation in percept space is associated with time-limited perceptions. This coding of different percepts by synchronized spike trains entails fundamental quantum features which are not restricted to microscopic phenomena. It is conjectured that they are related to the details of the perceptual chain rather than depending on Planck's action