A perfectly matched layer (PML) absorbing material composed of a uniaxial anisotropic material is presented for the truncation of finite-difference time-domain (FDTD) lattices. It is shown that the uniaxial PML material formulation is mathematically equivalent to the perfectly matched layer method published by Berenger (see J. Computat. Phys., Oct. 1994). However, unlike Berenger's technique, the uniaxial PML absorbing medium presented in this paper is based on a Maxwellian formulation. Numerical examples demonstrate that the FDTD implementation of the uniaxial PML medium (...) is stable, equal in effectiveness as compared to Berenger's PML medium, while being more computationally efficient. (shrink)

Explanations in the life sciences frequently involve presenting a model of the mechanism taken to be responsible for a given phenomenon. Such explanations depart in numerous ways from nomological explanations commonly presented in philosophy of science. This paper focuses on three sorts of differences. First, scientists who develop mechanistic explanations are not limited to linguistic representations and logical inference; they frequently employ diagrams to characterize mechanisms and simulations to reason about them. Thus, the epistemic resources for presenting mechanistic explanations are (...) considerably richer than those suggested by a nomological framework. Second, the fact that mechanisms involve organized systems of component parts and operations provides direction to both the discovery and testing of mechanistic explanations. Finally, models of mechanisms are developed for specific exemplars and are not represented in terms of universally quantified statements. Generalization involves investigating both the similarity of new exemplars to those already studied and the variations between them. (shrink)

How can phenomenal consciousness exist as an integral part of a physical universe? How can the technicolour phenomenology of our inner lives be created out of the complex neural activities of our brains? Many have despaired of finding answers to these questions; and many have claimed that human consciousness is inherently mysterious. Peter Carruthers argues, on the contrary, that the subjective feel of our experience is fully explicable in naturalistic terms. Drawing on a variety of interdisciplinary resources, he develops and (...) defends a novel account in terms of higher-order thought. He shows that this can explain away some of the more extravagant claims made about phenomenal consciousness, while substantively explaining the key subjectivity of our experience. Written with characteristic clarity and directness, and surveying a wide range of extant theories, this book is essential reading for all those within philosophy and psychology interested in the problem of consciousness. (shrink)

Keith Oatley draws on theories from psychology, philosophy and linguistics, as well as writings from other social sciences, to show how emotions are central to any understanding of human actions and mental life.

Contrary to standard assumptions, reasoning is often an emotional process. Emotions can have good effects, as when a scientist gets excited about a line of research and pursues it successfully despite criticism. But emotions can also distort reasoning, as when a juror ignores evidence of guilt just because the accused seems like a nice guy. In _Hot Thought_, Paul Thagard describes the mental mechanisms -- cognitive, neural, molecular, and social -- that interact to produce different kinds of human thinking, from (...) everyday decision making to legal reasoning, scientific discovery, and religious belief, and he discusses when and how thinking and reasoning should be emotional. Thagard argues that an understanding of emotional thinking needs to integrate the cognitive, neural, molecular, and social levels. Many of the chapters employ computational models of various levels of thinking, including HOTCO models and the more neurologically realistic GAGE model. Thagard uses these models to illuminate thinking in the domains of law, science, and religion, discussing such topics as the role of doubt and reasonable doubt in legal and other contexts, valuable emotional habits for successful scientists, and the emotional content of religious beliefs. Identifying and assessing the impact of emotion, Thagard argues, can suggest ways to improve the process of reasoning. (shrink)

In "Upheavals of Thought", Martha Nussbaum offers a theory of the emotions. She argues that emotions are best conceived as thoughts, and she argues that emotion-thoughts can make valuable contributions to the moral life. She develops extensive accounts of compassion and erotic love as thoughts that are of great moral import. This paper seeks to elucidate what it means, for Nussbaum, to say that emotions are forms of thought. It raises critical questions about her conception of the structure of emotion, (...) and about her conception of compassion, in particular. Finally, the paper seeks to show how analyzing the structure, as well as the moral value, of the emotions ultimately requires entering the realm of religious ethics. (shrink)

This paper evaluates four competing psychological explanations for why the jury in the O.J. Simpson murder trial reached the verdict they did: explanatory coherence, Bayesian probability theory, wishful thinking, and emotional coherence. It describes computational models that provide detailed simulations of juror reasoning for explanatory coherence, Bayesian networks, and emotional coherence, and argues that the latter account provides the most plausible explanation of the jury's decision.

We argue that computation via quantum mechanical processes is irrelevant to explaining how brains produce thought, contrary to the ongoing speculations of many theorists. First, quantum effects do not have the temporal properties required for neural information processing. Second, there are substantial physical obstacles to any organic instantiation of quantum computation. Third, there is no psychological evidence that such mental phenomena as consciousness and mathematical thinking require explanation via quantum theory. We conclude that understanding brain function is unlikely to require (...) quantum computation or similar mechanisms. (shrink)

This target article presents a new computational theory of explanatory coherence that applies to the acceptance and rejection of scientific hypotheses as well as to reasoning in everyday life, The theory consists of seven principles that establish relations of local coherence between a hypothesis and other propositions. A hypothesis coheres with propositions that it explains, or that explain it, or that participate with it in explaining other propositions, or that offer analogous explanations. Propositions are incoherent with each other if they (...) are contradictory, Propositions that describe the results of observation have a degree of acceptability on their own. An explanatory hypothesis is acccpted if it coheres better overall than its competitors. The power of the seven principles is shown by their implementation in a connectionist program called ECHO, which treats hypothesis evaluation as a constraint satisfaction problem. Inputs about the explanatory relations are used to create a network of units representing propositions, while coherende and incoherence relations are encoded by excitatory and inbihitory links. ECHO provides an algorithm for smoothly integrating theory evaluation based on considerations of explanatory breadth, simplicity, and analogy. It has been applied to such important scientific cases as Lovoisier's argument for oxygen against the phlogiston theory and Darwin's argument for evolution against creationism, and also to cases of legal reasoning. The theory of explanatory coherence has implications for artificial intelligence, psychology, and philosophy. (shrink)

Death.--The absurd.--Moral luck.--Sexual perversion.--War and massacre.--Ruthlessness in public life.--The policy of preference.--Equality.--The fragmentation of value.--Ethics without biology.--Brain bisection and the unity of consciousness.--What is it like to be a bat?--Panpsychism.--Subjective and objective.

In "The Quest for Consciousness," Caltech neuroscientist Christof Koch explores the biological basis of consciousness.

The position advanced in this paper is that the bedrock of emotional feelings is contained within the evolved emotional action apparatus of mammalian brains. This dual-aspect monism approach to brain–mind functions, which asserts that emotional feelings may reflect the neurodynamics of brain systems that generate instinctual emotional behaviors, saves us from various conceptual conundrums. In coarse form, primary process affective consciousness seems to be fundamentally an unconditional “gift of nature” rather than an acquired skill, even though those systems facilitate skill (...) acquisition via various felt reinforcements. Affective consciousness, being a comparatively intrinsic function of the brain, shared homologously by all mammalian species, should be the easiest variant of consciousness to study in animals. This is not to deny that some secondary processes cannot be evaluated in animals with sufficiently clever behavioral learning procedures, as with place-preference procedures and the analysis of changes in learned behaviors after one has induced re-valuation of incentives. Rather, the claim is that a direct neuroscientific study of primary process emotional/affective states is best achieved through the study of the intrinsic , albeit experientially refined, emotional action tendencies of other animals. In this view, core emotional feelings may reflect the neurodynamic attractor landscapes of a variety of extended trans-diencephalic, limbic emotional action systems—including SEEKING, FEAR, RAGE, LUST, CARE, PANIC, and PLAY. Through a study of these brain systems, the neural infrastructure of human and animal affective consciousness may be revealed. Emotional feelings are instantiated in large-scale neurodynamics that can be most effectively monitored via the ethological analysis of emotional action tendencies and the accompanying brain neurochemical/electrical changes. The intrinsic coherence of such emotional responses is demonstrated by the fact that they can be provoked by electrical and chemical stimulation of specific brain zones—effects that are affectively laden. For substantive progress in this emerging research arena, animal brain researchers need to discuss affective brain functions more openly. Secondary awareness processes, because of their more conditional, contextually situated nature, are more difficult to understand in any neuroscientific detail. In other words, the information-processing brain functions, critical for cognitive consciousness, are harder to study in other animals than the more homologous emotional/motivational affective state functions of the brain. (shrink)

This book brings together an international group of neuroscientists and philosophers who are investigating how the content of subjective experience is...

Progress in the neurosciences is profoundly changing our conception of ourselves. Contrary to time-honored intuition, the mind turns out to be a complex of brain functions. And contrary to the wishful thinking of some philosophers, there is no stemming the revolutionary impact that brain research will have on our understanding of how the mind works. Brain-Wise is the sequel to Patricia Smith Churchland's Neurophilosophy, the book that launched a subfield. In a clear, conversational manner, this book examines old questions about (...) the nature of the mind within the new framework of the brain sciences. What, it asks, is the neurobiological basis of consciousness, the self, and free choice? How does the brain learn about the external world and about its own introspective world? What can neurophilosophy tell us about the basis and significance of religious and moral experiences? Drawing on results from research at the neuronal, neurochemical, system, and whole-brain levels, the book gives an up-to-date perspective on the state of neurophilosophy—what we know, what we do not know, and where things may go from here. (shrink)

The concept of mechanism is analyzed in terms of entities and activities, organized such that they are productive of regular changes. Examples show how mechanisms work in neurobiology and molecular biology. Thinking in terms of mechanisms provides a new framework for addressing many traditional philosophical issues: causality, laws, explanation, reduction, and scientific change.

One of the most vivid aspects of consciousness is the experience of emotion, yet this topic is given relatively little attention within consciousness studies. Emotions are crucial, for they provide quick and motivating assessments of value, without which action would be misdirected or absent. Emotions also involve linkages between phenomenal and intentional consciousness. This paper examines emotional consciousness from the standpoint of the representational theory of consciousness . Two interesting developments spring from this. The first is the need for the (...) representation of value, which is distinctive of emotional experience. The second is an extension of RTC’s theory of introspection to emotional states, revealing why emotional consciousness is so often introspective even though introspective abilities are not needed to experience emotions, and also explaining why introspection of emotional states is so much less reliable than that of other states of consciousness. (shrink)

Gut Reactions is an interdisciplinary defense of the claim that emotions are perceptions of changes in the body.

Paul E. Griffiths argues that most research on the emotions has been as misguided as Aristotelian efforts to study "superlunary objects" - objects...

The publication of this book is an event in the making. All over the world scientists, psychologists, and philosophers are waiting to read Antonio Damasio's new theory of the nature of consciousness and the construction of the self. A renowned and revered scientist and clinician, Damasio has spent decades following amnesiacs down hospital corridors, waiting for comatose patients to awaken, and devising ingenious research using PET scans to piece together the great puzzle of consciousness. In his bestselling Descartes' Error, Damasio (...) revealed the critical importance of emotion in the making of reason. Building on this foundation, he now shows how consciousness is created. Consciousness is the feeling of what happens-our mind noticing the body's reaction to the world and responding to that experience. Without our bodies there can be no consciousness, which is at heart a mechanism for survival that engages body, emotion, and mind in the glorious spiral of human life. A hymn to the possibilities of human existence, a magnificent work of ingenious science, a gorgeously written book, The Feeling of What Happens is already being hailed as a classic. (shrink)

Lycan not only uses the numerous arguments against materialism, and functionalist theories of mind in particular, to gain a more detailed positive view of the ..

The book is an extended study of the problem of consciousness. After setting up the problem, I argue that reductive explanation of consciousness is impossible , and that if one takes consciousness seriously, one has to go beyond a strict materialist framework. In the second half of the book, I move toward a positive theory of consciousness with fundamental laws linking the physical and the experiential in a systematic way. Finally, I use the ideas and arguments developed earlier to defend (...) a form of strong artificial intelligence and to analyze some problems in the foundations of quantum mechanics. (shrink)

This book presents the definitive exposition of 'prospect theory', a compelling alternative to the classical utility theory of choice. Building on the 1982 volume, Judgement Under Uncertainty, this book brings together seminal papers on prospect theory from economists, decision theorists, and psychologists, including the work of the late Amos Tversky, whose contributions are collected here for the first time. While remaining within a rational choice framework, prospect theory delivers more accurate, empirically verified predictions in key test cases, as well as (...) helping to explain many complex, real-world puzzles. In this volume, it is brought to bear on phenomena as diverse as the principles of legal compensation, the equity premium puzzle in financial markets, and the number of hours that New York cab drivers choose to drive on rainy days. Theoretically elegant and empirically robust, this volume shows how prospect theory has matured into a new science of decision making. (shrink)

“What is an emotion?” William James asked that question in the title of an essay he wrote in 1884, and his answer was that an emotion is a sensation brought about by bodily disturbance. Writing as a psychologist, he was concerned to help turn his discipline into a science. But as a philosopher writing about religious faith, by contrast, James argued that emotions must be understood in terms of such large and fuzzy issues as “the meaning of life.” The philosophy (...) of emotions and emotions research has since gone off in two quite different directions, one a broad-based perennial philosophical concern with the proper place of the emotions in ethics and living well, the other an increasingly sophisticated pursuit of the latest ammunition and theoretical weaponry in the biological and neurological sciences. (shrink)

The authors present a neurological theory of how cognitive information and emotional information are integrated in the nucleus accumbens during effective decision making. They describe how the nucleus accumbens acts as a gateway to integrate cognitive information from the ventromedial prefrontal cortex and the hippocampus with emotional information from the amygdala. The authors have modeled this integration by a network of spiking artificial neurons organized into separate areas and used this computational model to simulate 2 kinds of cognitive–affective integration. The (...) model simulates successful performance by people with normal cognitive–affective integration. The model also simulates the historical case of Phineas Gage as well as subsequent patients whose ability to make decisions became.. (shrink)

Explaining the nature and mechanisms of conscious experience in neurobiological terms seems to be an attainable, if yet unattained, goal. Research at many levels is important, including research at the cellular level that explores the role of recurrent pathways between thalamic nuclei and the cortex, and research that explores consciousness from the perspective of action. Conceptually, a clearer understanding of the logic of expressions such as ‘‘causes’’ and ‘‘correlates’’, and about what to expect from a theory of consciousness are required. (...) The logic of some terms, such as ‘‘qualia’’ and ‘‘reductionism’’, continues to generate misunderstandings about the scientific possibilities and limits. Experimentally, a deeper understanding of the role of the thalamus in coordinating activity across cortical levels, and a readiness to reconsider the orthodox approach to thalamocortical organization are also required. (shrink)

The purpose of this book is to build towards an explanation of just what the matter is.