Consciousness

Representation of consciousness from the seventeenth century by Robert Fludd, an English Paracelsian physician

Consciousness at its simplest is "sentience or awareness of internal or external existence".[1] Despite centuries of analyses, definitions, explanations and debates by philosophers and scientists, consciousness remains puzzling and controversial,[2] being "at once the most familiar and most mysterious aspect of our lives".[3] Perhaps the only widely agreed notion about the topic is the intuition that it exists.[4] Opinions differ about what exactly needs to be studied and explained as consciousness. Sometimes it is synonymous with 'the mind', other times just an aspect of mind. In the past it was one's "inner life", the world of introspection, of private thought, imagination and volition.[5] Today, with modern research into the brain it often includes any kind of experience, cognition, feeling or perception. It may be 'awareness', or 'awareness of awareness', or self-awareness.[6] There might be different levels or "orders" of consciousness,[7] or different kinds of consciousness, or just one kind with different features.[8] Other questions include whether only humans are conscious or all animals or even the whole universe. The disparate range of research, notions and speculations raises doubts whether the right questions are being asked.[9]

Examples of the range of descriptions, definitions or explanations are: simple wakefulness, one's sense of selfhood or soul explored by "looking within"; being a metaphorical "stream" of contents, or being a mental state, mental event or mental process of the brain; having phanera or qualia and subjectivity; being the 'something that it is like' to 'have' or 'be' it; being the "inner theatre" or the executive control system of the mind.[10]

Inter-disciplinary perspectives

Western philosophers since the time of Descartes and Locke have struggled to comprehend the nature of consciousness and how it fits into a larger picture of the world. These issues remain central to both continental and analytic philosophy, in phenomenology and the philosophy of mind, respectively. Some basic questions include: whether consciousness is the same kind of thing as matter; whether it may ever be possible for computing machines like computers or robots to be conscious; how consciousness relates to language; how consciousness as Being relates to the world of experience; the role of the self in experience; whether individual thought is possible at all; and whether the concept is fundamentally coherent.

Recently, consciousness has also become a significant topic of interdisciplinary research in cognitive science, involving fields such as psychology, linguistics, anthropology,[11] neuropsychology and neuroscience. The primary focus is on understanding what it means biologically and psychologically for information to be present in consciousness—that is, on determining the neural and psychological correlates of consciousness. The majority of experimental studies assess consciousness in humans by asking subjects for a verbal report of their experiences (e.g., "tell me if you notice anything when I do this"). Issues of interest include phenomena such as subliminal perception, blindsight, denial of impairment, and altered states of consciousness produced by alcohol and other drugs, or spiritual or meditative techniques.

In medicine, consciousness is assessed by observing a patient's arousal and responsiveness, and can be seen as a continuum of states ranging from full alertness and comprehension, through disorientation, delirium, loss of meaningful communication, and finally loss of movement in response to painful stimuli.[12] Issues of practical concern include how the presence of consciousness can be assessed in severely ill, comatose, or anesthetized people, and how to treat conditions in which consciousness is impaired or disrupted.[13] The degree of consciousness is measured by standardized behavior observation scales such as the Glasgow Coma Scale.